Materials Handbook 2011 Part 15 ppt

Tripoli is used in massive form for themanufacture of filter stones for filtering small supplies of water.Missouri tripoli is also used for the manufacture of foundry parting.Finely grou

the tools can be coated in the fully hardened and tempered condition

without affecting hardness Tungsten carbide is another effective

coating One technique, developed by Rocklin Manufacturing and

called Rocklinizing, deposits 0.0001 to 0.0008 in (0.0025 to 0.0203

mm) of the carbide using a vibrating arcing electrode of the material

in a handheld gun Titanium carbide and titanium nitride are the

latest coatings The nitride, typically 0.0003 in (0.008 mm) thick, hasstirred the greatest interest, although the carbide may have advan-tages for press tools subject to high pressure In just the past fewyears, all sorts of tools, primarily cutters but also dies, have been tita-nium-nitride-coated, which imparts a gold- or brasslike look The

coating can be applied by chemical vapor deposition (CVD) at

1750 to 1950°F (954 to 1066°C) or by physical vapor deposition

(PVD) at 900°F (482°C) or less Thus, the PVD process has an

advan-tage in that the temperature involved may be within or below thetempering temperature of the tool steels so that the coating can beapplied to fully hardened and tempered tools Also, the risk of distor-tion during coating is less Titanium nitride coaters includeAerobraze, Multi-Arc Vacuum Systems, Scientific Coatings, StarCutter, Sylvester, and Ti-Coating Another method being used to pro-long tool life is to subject the tools to a temperature of 320°F(196°C) for about 30 h The cryogenic treatment, which has been

called Perm-O-Bond and Cryo-Tech by Materials Improvement, is

said to rid the steel of any retained austenite—thus the improved toollife Others in this business include Amcry, Endure, and 3XKryogenics

TRAGACANTH GUM. An exudation of the shrub Astragalus gummifer

of Asia Minor and Iran, used in adhesives or for mucilage, for leatherdressing, for textile printing, and as an emulsifying agent To obtain thegum, a small incision is made at the base of the shrub, from whichthe juice exudes and solidifies into an alteration product, not merely thedried juice The gum derived from the first day’s incision, known as

fiori, is the best quality and is in clear, fine ribbons or white flakes The

second incision produces a yellow gum known as biondo The third incision produces the poorest quality, a dark gum known as sari Rainy

weather during the incision period may cause a still inferior product.Tragacanth is insoluble in alcohol but is soluble in alkalies and swells

in water Karaya gum from southern Asia is from various species of

Sterculia trees, especially S urens, of India It is also known as

Indian gum, Indian hog gum, and hog tragacanth The sticky

gum is dried, and the chunks are broken and the pieces sorted bycolor A single chunk may have colors varying from clear white to darkamber and black The color is caused by tannin or other impurities

The No 3 grade, the lowest, has up to 3% insoluble impurities Thegum is marketed in flakes and as a white, odorless, 150-mesh powder.The chief constituent is galactan In general, the gum is more acidthan tragacanth and is likely to form lumpy gels unless finely ground.

It is widely used as a thickening and suspending agent for foodstuffs,drugs, cosmetics, adhesives, and textile finishes Gum tragacynth

thoroughly mixed with glycerin and water produces a thick paste,

tra-gacynth glycerite, a useful excipient to bind tablet masses For oral

ingestion, suspensions of gum tragacynth have been formulated One

such product is a suspension of procaine penicillin In hair lotion in

which there is 10% isopropanol, gum tragacynth is able to withstandthe alcohol without precipitation It is also a thickener of the aqueousphase in oil-in-water systems, resulting in shelf-stable emulsions

Regular as well as low-calorie salad dressings, such as Thousand

Island, French, and Roquefort, are such oil-in-water emulsions.

The low-calorie versions have higher amounts of gum tragacynth, toprovide the body that oil traditionally gives the regular dressing

Tragacynth gums, Type A.10, Type W, and Type L, are

pharmaceuti-cal grades in powder form, produced by Meer Corp

The granules of water-soluble gums, such as karaya, tragacanth,

and acacia, are swelled by water and dispersed in water in scopic particles to form cells or filamentlike structures which hold thewater like a sponge and will not settle out This type of colloidal dis-

micro-persion is called a hydrasol, and when thick and viscous is called a

gel From 2 to 3% of karaya or other gum will form a gel in water.

These gums will gel in cold water, while gelatin requires hot water fordissolving In a gel there is continuous structure with molecules form-

ing a network, while in a sol the particles are in separate suspension

and a sol is merely a dispersion Some dispersions, such as albumen,cross-link with heat; others, like guar gum, cross-link with alkalies;still others, like pectin, link with sugar and an acid Gums with weak

surface forces form weak gels which are pastes or mucilage, and a

high concentration is needed to produce a solid Karaya has great

swelling power, and is used in medicine as a bulk laxative Ghatti

gum, from the abundant tree Anogeissus latifolia of India, is entirely

soluble in water to form a viscous mucilage It is twice as effective asgum arabic as an emulsifier, but is less adhesive It comes in colorless

to pale-yellow tears of vitreous fracture, called also Indian gum, and

is used in India for textile finishing Aqualized gum, of Glyco

Products Co., Inc., is tragacanth or karaya chemically treated to givemore rapid solubility Water-soluble gums are also produced syntheti-

cally Polyox gum, of Union Carbide Chemicals Co., is a polymer of

polyethylene oxide containing carboxylic groups giving water ity when the pH is above 4.0 In paper coating with ammonia, the

ammonia evaporates to leave a water-insoluble, grease-resistant filmthat is heat-sealing It is also used in latex paints and in cosmetics.Another water-soluble gum which forms a true gel with a continuous

branched-chain molecular network is okra gum, produced as a

200-mesh tan powder It is edible and is used for thickening and stabilizingfoods and pharmaceuticals It is also used in plating baths for bright-ening nickel, silver, and cadmium plates It is extracted from the pods

of the okra, Hibiscus esculentus, a plant of the cotton family In the

southern states the pods, called gumbo, are used in soups The refined

gum, after extraction of the oils and sugars, contains 40.4% carbon, 6.1hydrogen, and 2.1 nitrogen, with the balance insoluble cellulose

TRIPOLI. A name given to finely granulated, white, porous, siliceousrock, used as an abrasive and as a filler True tripoli is an infusorial,

diatomaceous earth known as tripolite, and is a variety of opal, or

opaline silica In the abrasive industry it is called soft silica It is

quarried in Missouri, Illinois, eastern Tennessee, and Georgia.Pennsylvania rottenstone is not tripoli, although it is often classifiedwith it The material marketed for oil-well drilling mud under the

name of Opalite, is an amorphous silica The Missouri tripoli ranges

in color from white to reddish, and the crude rock has a porosity of45% and contains 30% or more of moisture It is air-dried and thencrushed and furnace-dried Tripoli is used in massive form for themanufacture of filter stones for filtering small supplies of water.Missouri tripoli is also used for the manufacture of foundry parting.Finely ground tripoli, free from iron oxide, is used as a paint filler and

in rubber The grade of tripoli known as O.G (once ground) is used forbuffing composition, D.G (double ground) for foundry partings, andthe air-float product for metal polishes Tripoli grains are soft, porous,and free from sharp cutting faces, and they give a fine polishing

effect It is the most commonly used polishing agent The word silex,

which is an old name for silica and is also used to designate the verized flint from Belgium, is sometimes applied to finely groundwhite tripoli employed as an inert filler for paints Much Illinois fine-grained tripoli is used for paint, and for this purpose it should be free

pul-from iron oxide Rottenstone is a soft, friable, earthy stone of light

gray to olive color, used as an abrasive for metal and wood finishing

It resembles Missouri tripoli and is derived from the weathering ofsiliceous-argillaceous limestone, with generally from 80 to 85% alu-mina, 4 to 15 silica, and 5 to 10 iron oxides Rottenstone was largelyimported from England, but one variety is found in Pennsylvania It

is finely ground and is marketed either as a powder or molded intobricks The latter form is used with oil on rag-wheel polishing A250-mesh powder is used as a filler in molding compounds

TRISODIUM PHOSPHATE. A white, crystalline substance of tion Na3PO4 12H2O, also known as phosphate cleaner, used in

composi-soaps, cleaning compounds, plating, textile processing, and boilercompounds The commercial grade is not less than 97% pure, withtotal alkalinity of 16 to 19% calculated as Na2O The anhydroustrisodium phosphate is 2.3 times as effective as the crystalline form,

but requires a longer time to dissolve Disodium phosphate is a

white, crystalline product of composition Na2HPO4 12H2O used forweighting silk, boiler treatment, cheese making, and cattle feeds.The medicinal, or USP, grade has only seven molecules of water andhas a different crystal structure The commercial grade is 99.4%

pure and is readily soluble in water Trisodium phosphate

hemi-hydrate is a granular, crystalline grade from FMC Corp for

degreasing and water conditioning Monosodium phosphate is

made by reacting soda ash with phosphoric acid in molecular portions; it is used in similar applications to the disodium variety

pro-Sodium tetraphosphate, Na6P4O13, contains 39.6% Na2O and 60.4

P2O5 It is the sodium salt of tetraphosphoric acid and is

mar-keted in beads that are mildly alkaline and highly soluble in water.The specific gravity is 2.55 and it melts at 1,112°F (600°C) It isused in the textile industry as a water softener and to acceleratecleansing operations It removes lime precipitation and sludge and

saves soap Quandrafos, of American Cyanamid Co., used to

replace quebracho for reducing the viscosity of oil-well drilling mud,

is sodium tetraphosphate, containing 63.5% P2O5 It makes the cium and magnesium compounds inactive, and 0.06% of the mater-ial controls 16.1% of water in reducing viscosity It also gives smoothflow with minimum water in paper coating and textile printing

cal-Metafos, of the same company, has a higher percentage of P2O5—67%—and a lower pH, for use in textile printing where low alkalin-

ity is needed Sodium pyrophosphate, Na4P2O7, is added to soappowders to increase the detergent effect and the lathering It is alsoused in oil-drilling mud The crystalline form, Na4P2O7 10H2O, isvery soluble in water and is noncaking, and it is used in household

cleaning compounds Sodium tripolyphosphate, Na5P3O10, is awater-soluble, white powder used as a detergent, a water softener,and a deflocculating agent in portland cement to govern the viscos-ity of the shale slurry without excessive use of water Large quanti-ties of these phosphates are used in the processing of chemicals,textiles, and paper; and since they are toxic contaminants of groundand surface waters, mill wastes must be deactivated before they aredischarged The use of phosphates in detergents and soap powdershas been banned in many areas since they lead to rapid algalgrowth in surface waters

TULIPWOOD Also called yellow poplar, whitewood, and canary

whitewood, the wood of the tree Liriodendron tulipifera of Canada

and the eastern United States The tree grows to a height of 250 ft(76 m) and to diameters of more than 10 ft (3 m) It is used for furni-ture, veneer, millwork, toys, woodenware, boxes, crates, and pulp-wood Owing to its close texture and even coefficient of expansion, ithas been used for expansion blocks in humidity regulators It is yel-lowish, soft, and durable The density is about 30 lb/ft3 (481 kg/m3)

The lumber may be mixed with cucumber magnolia, Magnolia acuminata, and evergreen magnolia, M grandifolia, but magnolia

woods are lighter in color.

TUNG OIL. A drying oil which has almost double the rapidity of seed oil It is used for enamels and varnishes; in brake linings, plasticcompounds, and linoleum; and for making pigment for India ink

lin-Tung oil is pressed from the seeds of Aleurites montana and A fordii.

The names wood oil and China wood oil are loosely and

erro-neously used to designate tung oils, but true wood oil is an oleoresin

from the Keruing tree of Malaya used for waterproofing and

caulk-ing boats, while tung oil is never from the wood The oil has a ful purgative action, and the Chinese word means stomach The

power-Chinese tung oil is from the nuts of the tree A montana, the China

wood oil tree, and A fordii The latter tree is hardier than A tana, which requires a hot climate The American tung oil is from the nuts of the tree A fordii of the Gulf states, which gives an annual

mon-production of about 30 lb (14 kg) of oil per tree The tree grows to aheight of 25 ft (8 m) and bears for 5 years The seeds, or nuts, contain

50 to 55% oil This tree is also grown in South Africa and Argentina.The color of tung oil varies from golden yellow to dark brownaccording to the degree of heat used in extraction It has a pungentodor resembling that of bacon fat A good grade of raw tung oil shouldhave a specific gravity between 0.934 and 0.940, a saponificationvalue of 190, and an iodine value of 163 The oil contains about 72%

eleostearic acid, which has a very high iodine value, 274, and gives

to the oil a greater drying power than is indicated by the iodine value

of the oil itself The oil has the property of drying throughout at auniform rate, instead of forming a skin as linseed oil does; but it driesflat instead of glossy, like linseed oil, and is inclined to produce awrinkled surface It is mixed with rosin, since rosin has great affinityfor it, and the two together are suitable for gloss varnishes In combi-nation with other drying oils, it improves water and alkali resistance,and is used mainly in quick-drying enamels and varnishes The oil

from A montana, or mu oil, has a higher percentage of eleostearic acid than that from A fordii The Japanese tung oil is from the

nuts of the larger tree A cordata The oil is superior to Chinese tung

oil and is seldom exported It does not gelatinize as Chinese tung oildoes, when heated It is used in Japan for varnishes, waterproofingpaper, and soaps The saponification value is 193 to 195, iodine value

of 149 to 159, and specific gravity 0.934 to 0.940 The kernels of thenuts yield about 40% oil The tree is grown also in Brazil and thrives

in hot climates Candlenut oil is from the seed nuts of A moluccana

of Oceania and southern Asia It received its name from the fact thatthe Polynesians used the nuts as candles to light their houses The oil

is variously known as kukui, kekune, and lumbang, and as an artist’s paint, oil is called walnut oil or artist’s oil The nut resem-

bles the walnut but has a thicker shell The oil has a specific gravity

of 0.923, iodine value 165, and is between linseed and soybean oil inproperties It is high in linoleic and linolenic acids The variety

known as soft lumbang oil, or bagilumbang oil, from the tree A.

trisperma of the Philippines, resembles tung oil and is high in

eleostearic acid The chief production of lumbang oil is in the FijiIslands

The Safflower, Carthamus tinctorius, is grown in California,

France, and India, and in the latter country it is grown on a large

scale for seeds, which yield up to 35% of the clear, yellowish

saf-flower oil used in paints, leather dressings, in the manufacture of

nonyellowing alkyd resins, and for foods The oil has a high content,73%, of linoleic acid, the highest of essential polyunsaturated acids ofany vegetable food oil It is odorless, with a bland taste, has a specific

gravity of 0.915, and an iodine value of 150 Safflower 22, of Pacific

Vegetable Oil Corp., is a conjugated paint oil made by isomerizing flower oil It has a rapid drying rate, color retention, and an ability toproduce wrinkled finishes by adjustment of the amount of drier Itcan thus replace tung oil It takes up maleic anhydride readily, and is

saf-used for making modified alkyd finishes Wecoline SF, of Drew

Chemical, is a concentrate of safflower fatty acids with 67.3% linoleic

acid and only 0.2 linolenic acid, for compounding in coatings Saff, of

Abbott Laboratories, is an emulsion of safflower oil used as a drug tolower blood cholesterol Refined and deodorized oil shows 2.8  106

lb (1.3 mg) of “cholesterol-equivalent” sterols per 0.22 lb (100 g) of oil.The heads of the plant are dried and used as food colors, for dyeingtextiles, and for cosmetic rouge

TUNGSTEN AND TUNGSTEN ALLOYS. A heavy, white metal, symbol W,with a specific gravity of 19.6, a density of 0.697 lb/in3(19,290 kg/m3),the highest melting point, 6170°F (3410°C), of all metals and a tensilestrength of 50,000 lb/in2 (345 MPa) at 2500°F (1370°C) Wolframite

is the chief ore of the metal tungsten Its composition is (FeMn)WO3

TUNGSTEN AND TUNGSTEN ALLOYS 985

986 TUNGSTEN AND TUNGSTEN ALLOYS

When the manganese tungstate is low, the ore is called ferberite; when the iron tungstate is low, it is called hübnerite The ore is con-

centrated by gravity methods to a concentrate containing 60 to 65%

tungstic oxide, WO3 To extract pure WO3from the concentrate, it isfused with sodium carbonate, Na2CO3, to form sodium tungstate,

Na2WO3, which is dissolved in water When an acid is added to thesolution, the WO3 precipitates out as a yellow powder The metallictungsten is obtained by reduction and is then pressed into bars andsintered Wolframite occurs usually bladed or columnar in form Ithas a specific gravity of 7.2 to 7.5, a Mohs hardness of 5, a black color,and a submetallic luster It is found in the mountain states, Alaska,China, and Argentina, but it also widely distributed in various parts

of the world in small quantities Chinese wolfram concentrates

contain 65% tungstic oxide; the Arizona concentrates contain an age of 67% California and Nevada concentrates are scheelite contain-

aver-ing from 60 to 67% tungstic oxide The sanmartinite of Argentina is

a variety containing zinc

Tungsten has a wide usage in alloy steels, magnets, heavy metals,electric contacts, rocket nozzles, and electronic applications It is alsoused for x-ray and gamma-ray shielding and wear-resistant surfaces,electroplates providing Vickers 700 or greater hardness Tungstenresists oxidation at very high temperatures and is not attacked bynitric, hydrofluoric, or sulfuric acid solutions Flame-sprayed coatingsare used for nozzles and other parts subject to heat erosion

Tungsten alloys are used for weights and counterbalances, radiation

shielding, grinding tools, tooling, and high-temperature applications

Copper-tungsten composites and silver-tungsten composites

serve as resistance-welding die inserts, electrode facings, electricalcontacts, heat sinks, wear surfaces, and electrodes for electrical-dis-charge machining (EDM) and electrochemical machining

Tungsten is usually added to iron and steel in the form of

ferro-tungsten, made by electric-furnace reduction of the oxide with iron or

by reducing tungsten ores with carbon and silicon Standard gradeswith 75 to 85% tungsten have melting points from 3200 to 3450°F

(1760 to 1899°C) Tungsten powder is usually in sizes from 200 to

325 mesh, and may be had in a purity of 99.9% Parts, rods, and sheetare made by powder metallurgy, and rolling and forging are done athigh temperature The rolled metal may have a tensile strength ashigh as 500,000 lb/in2 (3,448 MPa) and a Brinell hardness of 290,whereas drawn wire may have a tensile strength to 590,000 lb/in2

(4,068 MPa) The tungsten powder is used for spray coatings for

radia-tion shielding and for powder-metal parts Tungsten wire is used for spark plugs and electronic devices, and tungsten filaments are used

in lamps Tungsten wire as fine as 0.00018 in (0.00046 cm) is used in

TUNGSTEN AND TUNGSTEN ALLOYS 987

electronic hardware, and as thin as 0.0004 in (0.001 cm) for wire

EDM Tungsten whiskers, which are extremely fine fibers, are used

in copper alloys to add strength Copper wire, which normally has atensile strength of 30,000 lb/in2 (207 MPa), will have a strength of120,000 lb/in2 (827 MPa) when 35% of the wire is tungsten whiskers

Tungsten yarns are made up of fine fibers of the metal The yarns

are flexible and can be woven into fabrics Continuous tungsten ments, usually 394 to 591
in (10 to 15
m) in diameter, are used forreinforcement in metal, ceramic, and plastic composites Finer fila-

fila-ments are used as cores, or substrates, for boron filafila-ments.

The metal is also produced as arc-fused grown crystals, usually nolarger than 0.375 in (0.952 cm) in diameter and 10 in (25.4 cm) long,

and worked into rod, sheet, strip, and wire Tungsten crystals,

99.9975% pure, are ductile even at very low temperatures, and wire

as fine as 0.003 in (0.008 cm) and strip as thin as 0.005 in (0.013 cm)can be cold-drawn and cold-rolled from the crystal The crystal metalhas nearly zero porosity, and its electrical and heat conductivities arehigher than those of ordinary tungsten The normal electrical conduc-tivity is about 33% that of copper, but that of the crystal is 15%higher The molecules of tungsten appear as body-centered cubes, but

in the pure metal the atoms normally bond uniformly in six tions, forming a double lattice so that each grain forms a true singlecrystal At elevated temperatures, tungsten forms many compounds

direc-in chemicals and alloys One tungsten-alumdirec-inum alloy is a

chemi-cal compound made by reducing tungsten hexachloride with molten

aluminum Tungsten-rhenium alloys, in wire, rod, sheet, and plate

from Rhenium Alloys, Inc., include tungsten-26 rhenium, tungsten-25rhenium and tungsten-5 rhenium The W-25Re alloy has a density of0.711 lb/in3(19,680 kg/m3) and melts at 5522°F (3050°C) The electri-cal conductivity is 6% IACS, the ultimate tensile strength is 225,000lb/in2 (1,551 MPa), the elongation is 10%, and the tensile modulus is59,460,000 lb/in2(410,000 MPa)

Mi-Tech Metals Inc produces series of tungsten-based metals or

alloys for various requirements The HD tungsten Series, for

high-density, high-strength applications, contains 90 to 97% tungsten, plusnickel, iron, or copper, or iron and molybdenum Depending on grade,density ranges from 0.614 to 0.668 lb/in3 (17,000 to 18,500 kg/m3),hardness is 24 to 32 Rockwell C, ultimate tensile strength is 110,000

to 125,000 lb/in2 (758 to 862 MPa), tensile yield strength is 80,000 to95,000 lb/in2 (552 to 655 MPa), and elongation is 4 to 10% Also, thetensile modulus is 40  106 to 53  106 lb/in2 (276,000 to 365,000MPa), electrical conductivity is 13 to 17%, and most grades areslightly magnetic Typical uses include crankshaft balancing, radia-tion shielding, rotating inertia members, ordnance parts, boring bars

988 TUNGSTEN CARBIDE

and grinding quills and dies for die casting, extrusion, and hot

upset-ting A CW tungsten-copper Series, with 68 to 80% tungsten and

the balance copper, is used for electrical-discharge and cal machining Another, 74 tungsten-26 silver, is also used for EDM.Tungsten-copper grades, with 28 to 55% electrical conductivity, areused for resistance welding, resistance-welding electrode facings,flash-butt-welding dies, and hot upsetting dies Other metals made by

electrochemi-the company are copper– or copper alloy–tungsten carbide and

Elecon tungsten-copper and tungsten-silver, tungsten

carbide–silver, and molybdenum-silver electrical contact metals There’s also the Thermitech tungsten-copper Series for heat-sink

applications

Cobalt-tungsten alloy, with 50% tungsten, gives a plate that

retains a high hardness at red heat Tungsten RhC is a

tungsten-rhenium carbide alloy containing 4% tungsten-rhenium carbide It is used

for parts requiring high strength and hardness at high temperatures.The alloy retains a tensile strength of 75,000 lb/in2 (517 MPa) at

3500°F (1927°C) Ammonium metatungstate, used for

electroplat-ing, is a white powder of composition (NH4)6H2W12O40 It is readilysoluble in water and gives solutions of 50% tungsten content

Tungsten hexafluoride is used for producing tungsten coatings by

vapor deposition At a temperature of 900°F (482°C) the gas mixed

with hydrogen deposits a tungsten plate Tungsten hexachloride,

WCl6, is also used for depositing tungsten coatings at that ture in a hydrogen atmosphere Smooth, dense tungsten plates can

tempera-be deposited from tungsten carbonyl, W(CO)6, at a temperature of302°F (150°C) The carbonyl is made by reacting the hexachloridewith carbon monoxide

TUNGSTEN CARBIDE. An iron-gray powder of minute cubical crystalswith a Mohs hardness above 9.5 and a melting point of about 5400°F(2982°C) It is produced by reacting a hydrocarbon vapor with tung-sten at high temperature The composition is WC, but at high heat itmay decompose into W2C and carbon, and the carbide may be a mix-ture of the two forms Other forms may also be produced, such as W3Cand W3C4 Tungsten carbide is used chiefly for cutting tool bits andfor heat- and erosion-resistant parts and coatings

Briquetting of tungsten carbide into usable form was firstpatented in Germany and produced by Krupp Works under the

name of Widia metal It is made by diffusing powdered cobalt

through the finely divided carbide under hydraulic pressure, andthen sintering in an inert atmosphere at about 2732°F (1500°C).The briquetted material is ground to shape, and the pieces arebrazed into tools They withstand cutting speeds from 3 to 10 times

those of high-speed steel, and will turn manganese steel with aBrinell hardness of 550, but are not shock-resistant Pressed andsintered parts usually contain 3 to 20% cobalt binder, but nickelmay also be used as a binder The compressive strengths may be ashigh as 700,000 lb/in2 (4,827 MPa) with rupture strengths to200,000 lb/in2(1,379 MPa) or higher.

One of the earliest of the U.S bonded tungsten carbides was

Carboloy, of General Electric Co., used for cutting tools, gages,

drawing dies, and wear parts The sintered materials have been

sold under many trade names such as Dimondite, Firthite, and

Firthaloy; Armide, of Armstrong Bros Tool Co.; Wilcoloy; and Borium and Borod, of Stoody Co But the carbides are now often

mixed carbides Carboloy 608 contains 83% chromium carbide, 2

tungsten carbide, and 15 nickel binder It is lighter in weight thantungsten carbide, is nonmagnetic, and has a Rockwell A hardness to

93 It is used for wear-resistant parts and resists oxidation to2000°F (1092°C) Titanium carbide is more fragile, but may be

mixed with tungsten carbide to add hardness for dies Cutanit is such a mixture Kennametal K601, of Kennametal, Inc., for seal

rings and wear parts, is a mixture of tantalum and tungsten bides without a binder It has a compressive strength of 675,000lb/in2 (4,654 MPa), rupture strength of 100,000 lb/in2 (690 MPa),

car-and Rockwell A hardness of 94 Kennametal K501 is tungsten

carbide with a platinum binder for parts subject to severe heat

ero-sion Strauss metal, of Allegheny Ludlum Steel Co., is tungsten carbide Tungsten carbide LW-1 is tungsten carbide with about

6% cobalt binder used for flame-coating metal parts to give temperature wear resistance Deposited coatings have a Vickers

high-h a r d n e s s t o 1 , 4 5 0 a n d r e s i s t o x i d a t i o n a t 1 0 0 0 ° F ( 5 3 8 ° C )

Tungsten carbide LW-1N, with 15% cobalt binder, has a much

higher rupture strength, but the Vickers hardness is reduced to

1,150 Metco 35C is a fine powder of tungsten carbide and cobalt

for flame spraying to produce a wear-resistant coating of carbide in

a matrix of cobalt GPX 9660, of Securamax International, is a

tungsten carbide and cobalt coating applied by flame spraying toincrease the wear resistance and, to some extent, the corrosionresistance of steel parts A tungsten carbide and nickel formula-

tion, GPX 9657, also increases wear resistance and provides better

corrosion resistance Tungsten carbide chemically bonded to a ified nickel aluminide, developed at the U.S Department ofEnergy’s Oak Ridge National Laboratory and patented by DowChemical and Martin Marietta Energy Systems, is harder and perhapsmore durable than tungsten carbide–cobalt in rock-, coal-, andmetal-cutting applications

TUNGSTEN STEEL. Any steel containing tungsten as the alloying ment imparting the chief characteristics to the steel It is one of theoldest of the alloying elements in steel, the celebrated ancientEastern sword steels having contained tungsten Tungsten increasesthe hardness of steel, and gives it the property of red hardness, stabi-lizing the hard carbides at high temperatures It also widens thehardening range of steel and gives deep hardening Very small quan-tities serve to produce a fine grain and raise the yield point Thetungsten forms a very hard carbide and an iron tungstite, and thestrength of the steel is also increased, but it is brittle when the tung-sten content is high When large percentages of tungsten are used insteel, they must be supplemented by other carbide-forming elements.Tungsten steels, except the low-tungsten chromium-tungsten steels,are not suitable for construction; but they are widely used for cuttingtools, because the tungsten forms hard, abrasion-resistant particles inhigh-carbon steels Tungsten also increases the acid resistance andcorrosion resistance of steels The steels are difficult to forge and can-not be readily welded when tungsten exceeds 2% Standard

ele-tungsten-chromium alloy steels 72XX contain 1.5 to 2% tungsten

and 0.50 to 1 chromium Many tool steels rely on tungsten as analloying element, and it may range from 0.50 to 2.50% in cold-workand shock-resisting types to 9 to 18 in the hot-work type, and 12 to 20

in high-speed steels

TURPENTINE Also called in the paint industry oil of turpentine.

An oil obtained by steam distillation of the oleoresin which exudeswhen various conifer trees are cut Longleaf pine and slash pine arethe main sources It also includes oils obtained by distillation and sol-vent extraction from stumpwood and waste wood Longleaf sapwoodcontains about 2% oleoresin, heartwood 7 to 10%, and stumpwood25% Most oleoresin is obtained from the sapwood of living trees, but

it is not the sap of the tree Heartwood resin is obtained only whenthe cut wood is treated with solvents The oleoresin yields about 20%

oil of turpentine and 80 rosin; both together are known as naval

camphene Some wood turpentine is produced as a by-product in the

manufacture of cellulose Sulfate turpentine is a by-product in the

making of wood pulp It varies in composition as the less stable betapinene is affected by the pulping process, and it is used largely inchemical manufacture By hydrogenation it produces cymene from

which dimethyl styrene is made This material can be

copolymer-ized to produce vinyl resins

Turpentine varies in composition according to the species of pinefrom which it is obtained It is produced chiefly in the United States,

France, and Spain The turpentine of India comes from the chir

pine, Pinus longifolia, of the southern slopes of the Himalayas, also

valued for lumber, and the khasia pine, P khasya The gum of the

chir pine is different from U.S gum, and the turpentine, unless fully distilled, is slower-drying and greasy French and Spanish tur-

care-pentine, or Bordeaux turcare-pentine, is from the maritime pine, P pinaster, which is the chief source, and from Aleppo pine, P halepensis, and Corsican pine, P lavicia In Portugal, the stone

pine, P pinea, is the source The French maritime pine is also grown

on plantations in Australia Aleppo pine of Greece was the source of

the naval stores of the ancients Venetian turpentine, or Venice

turpentine, is from the Corsican pine or European larch It produces

a harder film than U.S turpentine Artificial Venice turpentine ismade by mixing rosin with turpentine European pines do not give ashigh a yield as U.S longleaf and slash pines

American turpentine oil boils at 309°F (154°C), and the specificgravity is 0.860 It is a valuable drying oil for paints and varnishes,owing to its property of rapidly absorbing oxygen from the atmo-sphere and transferring it to the linseed or other drying oil, whichleaves a tough and durable film of paint Turpentine is also used inthe manufacture of artificial camphor and rubber, and in linoleum,

soap, and ink Gum thus, used in artists’ oil paints, is thickened

tur-pentine, although gum thus was originally made from olibanum.Turpentine is often adulterated with other oils of the pine or withpetroleum products, and the various states have laws regulating itsadulteration for paint use

The pinene in European turpentine is levorotatory while that in the United States is dextrorotatory Pinonic acid is acetyl dimethyl

cyclobutane acetic acid It is produced by oxidation of the pinene and

is a white powder used as a cross-linking agent for making ble plastics

heat-sta-Terpene alcohol, or methylol pinene, C11H17OH, is produced bycondensing the beta pinene of gum turpentine with formaldehyde

Nopol, of Glidden Co., is terpene alcohol It has the chemical

reac-tions of both a primary alcohol and pinene, and it is used in making

many chemicals It is a water-insoluble liquid of specific gravity

0.963, boiling at 455°F (235°C) Terpineol is a name for refined

ter-pene alcohols used largely for producing essential oils and perfumes

Piccolyte resin is a terpene thermoplastic varnish resin made from

turpentine The grades have melting points from 50 to 257°F (10 to

125°C) Myrcene is a polyolefin with three double bonds, which can

be used as a substitute for butadiene in the manufacture of syntheticrubbers, or can be reacted with maleic anhydride or dibasic acids toform synthetic resins It is made by isomerizing the beta pinene of

gum turpentine Camphene is produced by isomerizing the alpha

pinene of turpentine Camphor is then produced by oxidation of phene in acid Camphene was also the name of a lamp oil of the earlynineteenth century made from distilled turpentine and alcohol Itgave a bright white light, but was explosive The insecticide known as

cam-Toxaphene, of Hercules Inc., is made by chlorinating camphene to

68% chlorine, or to the empirical formula C10H20Cl8 It is a yellow,waxy powder with a piney odor, melting at 149 to 194°F (65 to 90°C)

It is soluble in petroleum solvents

TURQUOISE. An opaque-blue gemstone with a waxy luster It is ahydrous phosphate of aluminum and copper oxides It is found in thewestern United States in streaks in volcanic rocks, but most of theturquoise has come from the Kuh-i-Firouzeh, or turquoise mountain,

of Iran, which is a vast deposit of brecciated porphyry, or feldsparigneous rock The valuable stones are the deep blue The pale blue

and green stones were called Mecca stones because they were sent

to Mecca for sale to pilgrims Bone turquoise, or odontolite, used

for jewelry, is fossil bone or tooth, colored by a phosphate of iron

TYPE METAL. Any metal used for making printing type, but the name

generally refers to lead-antimony-tin alloys Antimony has the

prop-erty of expanding on cooling and thus fills the mold and producessharp, accurate type The properties required in a type metal are abil-ity to make sharp, uniform castings; strength and hardness; fairly lowmelting point; narrow freezing range to facilitate rapid manufacture

in type-making machines; and resistance to drossing A common typemetal is composed of 9 parts lead to 1 antimony, but many varieties ofother mixtures are also used The antimony content may be as high as

30%, 15 to 20% being frequent A common monotype metal has 72%

lead, 18 antimony, and 10 tin Larger and softer types are made ofother alloys, sometimes containing bismuth; the hardest small typecontains 3 parts lead to 1 antimony A low-melting-point, soft-typemetal contains 22% bismuth, 50 lead, and 28 antimony It will melt atabout 310°F (154°C) Copper, up to 2%, is sometimes added to type

metal to increase the hardness, but is not ordinarily used in metalsemployed in rapid-acting type machines Some monotype metal has

about 18% antimony, 8 tin, and 0.1 copper, but standard linotype

metal for pressure casting has 79% lead, 16 antimony, and 5 tin Stereotype metal, for sharp casting and hard-wearing qualities, is

given as 80.0% lead, 13.5 antimony, 6 tin, and 0.5 copper Intertype

metal has 11 to 14% antimony and 3 to 5 tin A typical formula for electrotype metal is 94% lead, 3 tin, and 3 antimony The Brinell

hardness of machine-molded type ranges from 17 to 23, and that ofstereotype metal is up to 30 As constant remelting causes the separa-tion of the tin and lead, and the loss of tin, or impoverishment of themetal, new metal must be constantly added to prevent deterioration of

a standard metal into an inferior alloy For many years mony-tin alloys have been used as a weld seam filler in auto andtruck bodies In this application they are commonly referred to as

lead-anti-body solder Because of advances in printing technology and auto

manufacturing, use of these lead alloys is steadily declining

ULTRAHIGH-STRENGTH STEELS. The highest-strength steels able Arbitrarily, steels with tensile strengths of around 200,000 lb/in2

avail-(1,379 MPa) or higher are included in this category, and more than

100 alloy steels can be thus classified They differ rather widelyamong themselves in composition and/or the way in which the ultra-high strengths are achieved

Medium-carbon, low-alloy steels were the initial

ultrahigh-strength steels, and within this group, a chromium-molybdenum

steel (4130) grade and a chromium-nickel-molybdenum steel

(4340) grade were the first developed These steels have yieldstrengths as high as 240,000 lb/in2(1,655 MPa) and tensile strengthsapproaching 300,000 lb/in2 (2,069 MPa) They are particularly usefulfor thick sections because they are moderately priced and have deep

hardenability Several types of stainless steels are capable of

strengths above 200,000 lb/in2 (1,379 MPa), including a number ofmartensitic, cold-rolled austenitic, and semiaustenitic grades Thetypical martensitic grades are types 410, 420, and 431, as well as cer-

tain age-hardenable alloys The cold-rolled austenitic stainless

steels work-harden rapidly and can achieve 180,000 lb/in2 (1,241MPa) tensile yield strength and 200,000 lb/in2 (1,379 MPa) ultimate

strength Semiaustenitic stainless steels can be heat-treated for

use at yield strengths as high as 220,000 lb/in2(1,517 MPa) and mate strengths of 235,000 lb/in2(1,620 MPa)

ulti-Maraging steels contain 18 to 25% nickel plus substantial

amounts of cobalt and molybdenum Some newer grades containsomewhat less than 10% nickel and between 10 and 14 chromium

ULTRAHIGH-STRENGTH STEELS 993

Because of the low carbon (0.03% maximum) and nickel content,maraging steels are martensitic in the annealed condition, but arestill readily formed, machined, and welded By a simple aging treat-ment at about 900°F (482°C), yield strengths as high as 300,000 and350,000 lb/in2 (2,069 and 2,413 MPa) are attainable, depending onspecific composition In this condition, although ductility is fairly low,the material is still far from being brittle.

Among the strongest of plain carbon sheet steels are the low- and

medium-carbon sheet grades of Inland Steel, called MarTinsite.

Made by rapid water quenching after cold rolling, they provide tensileyield strengths to 220,000 lb/in2 (1,517 MPa) but are quite limited inductility

There are two types of ultrahigh-strength, low-carbon, hardenable

steels One, a chromium-nickel-molybdenum steel, named

Astralloy, with 0.24% carbon is air-hardened to a yield strength of

180,000 lb/in2 (1,241 MPa) in heavy sections when it is normalized

and tempered at 500°F (260°C) The other type is an

iron-chromium-molybdenum-cobalt steel and is strengthened by a

precipitation-hardening and aging process to levels up to 245,000lb/in2 (1,689 MPa) in yield strength High-alloy quenched-and-tem-

pered steels are another group that have extrahigh strengths They

contain 9% nickel, 4 cobalt, and from 0.20 to 0.30 carbon, and developyield strengths close to 300,000 lb/in2 (2,069 MPa) and ultimatestrengths of 350,000 lb/in2 (2,413 MPa) Another group in this high-

alloy category resembles high-speed tool steels, but is modified to

eliminate excess carbide, thus considerably improving ductility These

so-called matrix steels contain tungsten, molybdenum, chromium,

vanadium, cobalt, and about 0.5% carbon They can be heat-treated toultimate strengths of over 400,000 lb/in2 (2,758 MPa)—the higheststrength presently available in steels, except for heavily

cold-worked high-carbon steel strips used for razor blades and

drawn wire for musical instruments, both of which have tensilestrengths as high as 600,000 lb/in2(4,137 MPa)

Aermet 100, of Carpenter Technology, is a nickel and cobalt steel

strengthened by carbon, columbium, and molybdenum Originallydeveloped for aerospace applications, it combines high tensile yieldstrength [(250,000 lb/in2 (1,724 MPa)] and fracture toughness[(115,000 lb/in2 兹in苶 (126 MPa 兹m苶)] Uses include aircraft landinggears, racing-car shafts, racing-bicycle frames, mandrel-supportshafts, punch-base supports, and special bolting systems

URANIUM. An elementary metal, symbol U It never occurs free innature but is found chiefly as an oxide in the minerals pitchblendeand carnotite where it is associated with radium The metal has aspecific gravity of 18.68 and atomic weight 238.2 The melting point is

about 2071°F (1133°C) It is hard but malleable, resembling nickel incolor, but related to chromium, tungsten, and molybdenum It is solu-ble in mineral acids.

Uranium has three forms The alpha phase, or orthorhombic tal, is stable to 1220°F (660°C); the beta, or tetragonal, exists from

crys-1220 to 1400°F (660 to 760°C); and the gamma, or body-centeredcubic, is from 1400°F to the melting point The cast metal has aRockwell B hardness of 80 to 100, work-hardening easily The metal

is alloyed with iron to make ferrouranium, used to impart special

properties to steel It increases the elastic limit and the tensilestrength of steels, and is also a more powerful deoxidizer than vana-dium It will denitrogenize steel and has carbide-forming qualities Ithas been used in high-speed steels in amounts of 0.05 to 5% toincrease the strength and toughness, but because of its importancefor atomic applications its use in steel is now limited to the by-prod-

uct nonradioactive isotope uranium 238 The green salt used in atomic work is uranium tetrafluoride, UF4 Uranium hexafluo-

ride, UF6, is a gas used to separate uranium isotopes

Metallic uranium is used as a cathode in photoelectric tubesresponsive to ultraviolet radiation Uranium compounds, especiallythe uranium oxides, were used for making glazes in the ceramicindustry and also for paint pigments It produces a yellowish-green,fluorescent glass, and a beautiful red with yellowish tinge is produced

on pottery glazes Uranium dioxide, UO2, is used in sintered forms

as fuel for power reactors It is chemically stable and has a high ing point at about 5000°F (2760°C), but a low thermal conductivity.For fuel use the particles may be coated with about 0.001 in (0.003cm) of aluminum oxide This coating is impervious to xenon and otherradioactive isotopes so that only the useful power-providing rays canescape These are not dangerous at a distance of about 6 in (15 cm),and thus less shielding is needed For temperatures above 2300°F(1260°C) a coating of pyrolitic graphite is used

melt-Uranium has isotopes from 234 to 239, and uranium 235, with 92

protons and 143 neutrons, is the one valued for atomic work Thepurified natural metal contains only about one part U235to about 140parts of U238, and about 100,000 lb (45,360 kg) of uranium fluoride,

UF6, must be processed to obtain 1 lb (0.45 kg) of U235F6 Uranium

238, after the loss of three alpha particles of total mass 12, changes to radium 226 The lead of old uranium minerals came from Ra226 by

the loss of five alpha particles, and is lead 206, while the lead in rium metals is lead 208 Lead 207 comes from the decay of actinum

tho-and exists only in small quantities

Natural uranium does not normally undergo fission because of thehigh probability of the neutron being captured by the U238which thenmerely ejects a gamma ray and becomes U239 When natural uranium

is not in concentrated form, but is embodied in a matrix of graphite orheavy water, it will sustain a slow chain reaction sufficient to produceheat In the fission of U235, neutrons are created which maintain thechain reaction and convert U238 to plutonium About 40 elements ofthe central portion of the periodic table are also produced by the fis-sion, and eventually these products build up to a point where thereaction is no longer self-sustaining The slow, nonexplosive disinte-

gration of the plutonium yields neptunium Uranium 233 is made by

neutron bombardment of thorium This isotope is fissionable and isused in thermonuclear reactors

Uranium yellow, also called yellow oxide, is a sodium ranate of composition Na2U2O7 6H2O, obtained by reduction andtreatment of the mineral pitchblende It is used for yellow and green-ish glazing enamels and for imparting an opalescent yellow to glass,

diu-which is green in reflected light Uranium oxide is an olive-green

powder of composition U3O8, used as a pigment Uranium trioxide,

UO3, is an orange-yellow powder also used for ceramics and pigments

It is also called uranic oxide As a pigment in glass, it produces a beautiful greenish-yellow uranium glass Uranium pentoxide,

U2O5, is a black powder, and uranous oxide, UO2, is used in glass to

give a fine black color Sodium uranate, Na2UO4, is a yellow toorange powder used to produce ivory to yellow shades in potteryglazes The uranium oxide colors give luster and iridescence, butbecause of the application of the metal-to-atom work, the uses in pig-ments and ceramics are now limited

URANIUM ORES The chief source of radium and uranium is

urani-nite, or pitchblende, a black, massive or granular mineral with

pitchlike luster The mineral is a combination of the oxides of nium, UO2, UO3, and U3O8, together with small amounts of lead, tho-rium, yttrium, cerium, helium, argon, and radium The process ofseparation of radium is chemically complicated Uraninite is foundwith the ores of silver and lead in central Europe In the United States

ura-it occurs in pegmatura-ite veins, in the mica mines of North Carolina, and

in the carnotite of Utah and Colorado The richest ores come from theCongo and from near Great Bear Lake, Canada About 370 tons (336metric tons) of Great Bear Lake ore produces 0.002 lb (1 g) of radiumand 7,800 lb (3,538 kg) of uranium, and small amounts of polonium,ionium, silver, and radioactive lead Numerous minor uranium oresoccur in many areas A low-grade ore of 0.1% U3O8can be upgraded to

as high as 5% by ion exchange Black mud from the fjords of Norwaycontains up to 2 oz (0.06 kg) of uranium per long ton (1 metric ton)

Tyuyamunite, found in Turkman, averages 1.3% U3O8, with radium,

vanadium, and copper Autunite, or uranite, is a secondary mineral

from the decomposition of pitchblende The composition is mately P2O5 2UO3 CaO  8H2O It is produced in Utah, Portugal,

approxi-and south Australia Torbernite, or copper uranite,

Cu(UO2)2P2O8 12H2O, is a radioactive mineral of specific gravity

3.22 to 3.6 and Mohs hardness 2 to 2.5 Sengierite is a

copper-ura-nium mineral found in the Congo It occurs in small green crystals

Casolite is a yellow, earthy lead uranium silicate, 3(PbO UO3SiO2)4H2O Pilbarite is a thorium lead uranate Umohoite, found

in Utah, contains 48% uranium, with molybdenum, hydrogen, andoxygen The name of the ore is a combination of the symbols of thecontained elements Uranium is also recovered chemically from phos-phate rock The phosphate waste rock of Florida contains from 0.1 to0.4% U3O8 Most uranium ores contain less than 0.3% U3O8 Solventmethods of extraction are used

UREA Also called carbamide A colorless to white, crystalline

pow-der, NH2 CO  NH2, best known for its use in plastics and fertilizers.The chemistry of urea and the carbamates is very complex, and a verygreat variety of related products are produced Urea is produced by

combining ammonia and carbon dioxide, or from cyanamide, NH2

C N It is a normal waste product of animal protein metabolism and

is the chief nitrogen constituent of urine It was the first organicchemical ever synthesized commercially It has a specific gravity of1.323 and a melting point of 275°F (135°C) Industrial grades areavailable either as prills or as a 50% solution from Columbia NitrogenCorp An ultrapure enzyme grade is produced in small quantities byBethesda Laboratories, and material for electrophoresis by Bio-RadLaboratories

The formula for urea may be considered as O C(NH2)2, and thus as

an amide substitution in carbonic acid, O C(OH)2, an acid whichreally exists only in its compounds The urea-type plastics are called

amino resins The carbamates can also be considered as deriving

from carbamic acid, NH2COOH, an aminoformic acid that

like-wise appears only in its compounds The carbamates have the same

structural formula as the bicarbonates, so that sodium carbamate

has an NH2group substituted for each OH group of the sodium

bibonate The urethanes, used for plastics and rubber, are alkyl

car-bamates made by reacting urea with an alcohol, or by reacting

isocyanates with alcohols or carboxyl compounds They are whitepowders of composition NH2COOC2H5, melting at 122°F (50°C)

Isocyanates are esters of isocyanic acid, H N  C  O, which

does not appear independently The dibasic diisocyanate of General

Mills, Inc., is made from a 36-carbon fatty acid It reacts with pounds containing active hydrogen With modified polyamines it

forms polyurea resins, and with other diisocyanates it forms a wide range of urethanes Tosyl isocyanate, of Upjohn Co., for producing

urethane resins without a catalyst, is toluene sulphonyl isocyanate.The sulphonyl group increases the reactivity

Methyl isocyanate, CH3NCO, known as MIC, is a colorless liquid

with a specific gravity of 0.9599 It reacts with water With a flashpoint of less than 20°F (6.6°C), it is flammable and a fire risk It is astrong irritant and highly toxic One of its principal uses is as anintermediate in the production of pesticides

Urea is used with acid phosphates in fertilizers It contains about45% nitrogen and is one of the most efficient sources of nitrogen Urea

reacted with malonic esters produces malonyl urea, which is the

barbituric acid that forms the basis for the many soporific

com-pounds such as luminal, phenobarbital, and amytal The malonic esters are made from acetic acid, and malonic acid derived from the

esters is a solid of composition CH2(COOH)2 which decomposes atabout 320°F (160°C) to yield acetic acid and carbon dioxide

For plastics manufacture, substitution on the sulfur atom in

thiourea is easier than on the oxygen in urea Thiourea, NH2 CS 

NH2, also called thiocarbamide, sulfourea, and sulfocarbamide,

is a white, crystalline, water-soluble material of bitter taste, with aspecific gravity of 1.405 It is used for making plastics and chemicals

On prolonged heating below its melting point of 360°F (182°C), it

changes to ammonium thiocyanate, or ammonium sulfocyanide,

a white, crystalline, water-soluble powder of composition NH4SCN,melting at 302°F (150°C) This material is also used in making plas-tics, as a mordant in dyeing, to produce black nickel coatings, and as

a weedkiller Permafresh, of Warwick Chemical Co., used to control shrinkage and give wash-and-wear properties to fabrics, is dimethy-

lol urea, CO(NHCH2OH)2, which gives clear solutions in warmwater

Urea-formaldehyde resins are made by condensing urea or

thiourea with formaldehyde They belong to the group known as

aminoaldehyde resins made by the interaction of an amine and an

aldehyde An initial condensation product is obtained which is soluble

in water and is used in coatings and adhesives The final tion product is insoluble in water and is highly chemical-resistant.Molding is done with heat and pressure The urea resins are noted fortheir transparency and ability to take translucent colors Moldedparts with cellulose filler have a specific gravity of about 1.50, tensilestrength from 6,000 to 13,000 lb/in2 (41 to 90 MPa), elongation 15%,compressive strength to 45,000 lb/in2(310 MPa), dielectric strength to

condensa-400 V/mil (16  106 V/m), and heat distortion temperature to 280°F

(138°C) Rockwell M hardness is about 118 Urea resins are

keted under a wide variety of trade names The Uformite resins of

Rohm & Haas are water-soluble thermosetting resins for adhesives

and sizing The Urac resins, of American Cyanamid, and the Casco

resins and Cascamite, of Borden Co., are urea-formaldehyde.

Borden’s products are available as liquids, 55 to 66% solids, andspray-dried powder grades They are used as adhesives for plaster-

board and plywood and in wet-strength paper Resi-mat, from

Georgia-Pacific, is a liquid resin binder for glass-mat roofing andinsulation materials

URETHANES Also termed polyurethanes A group of plastic

materi-als based on polyether or polyester resin The chemistry involved isthe reaction of a diisocyanate with a hydroxyl-terminated polyester orpolyether to form a higher-molecular-weight prepolymer, which inturn is chain-extended by adding difunctional compounds containingactive hydrogens, such as water, glycols, diamines, or amino alcohols.The urethanes are block polymers capable of being formed by a liter-ally indeterminate number of combinations of these compounds Theurethanes have excellent tensile strength and elongation, good ozoneresistance, and good abrasion resistance Combinations of hardnessand elasticity unobtainable with other systems are possible in ure-thanes, ranging from Shore A hardness of 15 to 30 (printing rolls, pot-ting compounds) through A 60 to 90 for most industrial or mechanicalgoods applications, to Shore D 70 to 85 Urethanes are fairly resistant

to many chemicals such as aliphatic solvents, alcohols, ether, certainfuels, and oils They are attacked by hot water, polar solvents, andconcentrated acids and bases

Urethane foams are made by adding a compound that produces

carbon dioxide or by reaction of a diisocyanate with a compound taining active hydrogen Foams can be classified somewhat according

con-to modulus as flexible, semiflexible or semirigid, and rigid No sharplines of demarcation have been set on these different classes as thegradation from the flexible to the rigid is continuous Density of flexi-ble foams ranges from about 1.0 lb/ft3 (16 kg/m3) to 4 to 5 lb/ft3(64 to

80 kg/m3), depending on the end use Applications of flexible foamsrange from comfort cushioning of all types, e.g., mattresses, pillows,sofa seats, backs and arms, automobile topper pads, and rug under-lay, to clothing interliners for warmth at light weight Density of rigidurethane foams ranges from about 1.5 to 50 lb/ft3(24 to 800 kg/m3)

Confor, of E-A-R Specialty Composites, is a line of

temperature-sensitive urethane foams for cushioning and padding Surfaces incontact with body heat, for example, soften and conform to bodyshape while other regions remain stiff and supportive Unlike fast-recovery foams, recovery is slow They come in several stiffness

grades and colors TechnoGel, made by TechnoGel in Germany, is a

pliant polyurethane gel developed by Bayer and used for cushioning

seats, beds, and furniture Isoloss LS foams, of E-A-R, have a

fine-cell, high-density structure, featuring high-strength dimensional bility and low compression set Uses include seals, isolaters, and

sta-energy-absorbing mounts Conathane UC-38 and UC-39, of Conap,

Inc., are liquid, two-component, room-temperature-curing resins forprototype parts UC-38 has a tensile strength of 5,000 lb/in2(34 MPa),35% elongation, a Shore D hardness of 75, and a low shrinkage toyield precision parts UC-39 features a demold time of only 1 h

Thermoplastic polyurethanes (TPUs) include two basic types:

esters and ethers Esters are tougher, but hydrolyze and degradewhen soaked in water There also are TPUs based on polycaprolac-tone, which while technically being esters, have better resistance tohydrolysis TPUs are used when a combination of toughness, flexresistance, weatherability, and low-temperature properties is needed.These materials can be injection-molded, blow-molded, and extruded

as profiles, sheet, and film Further, TPUs are blended with otherplastic resins, including PVC, ABS, acetal, SAN, and polycarbonate.Polyol and isocyanate, two highly reactive components of ure-thanes, are used to form flexible bumper fascia for cars by reactioninjection molding (RIM) There are low- and high-modulus unrein-forced grades, as well as glass-reinforced grades for greater rigidity

There are several trade names, including Bayflex, of Miles Inc.

There are also grades for what is called structural reaction injection

molding (SRIM) Polydicyclopentadiene resins can be tailored for

RIM or SRIM Besides milled glass and flaked glass, wollastonite andmica fillers can be used for reinforcement and to improve surface fin-

ish Rimlite, of Miles, refers to the use of lightweight microspheres

as fillers

Urethane elastomers are made with various isocyanates, the

principal ones being TDI (tolylene diisocyanate) and MDI (4,4´-diphenylmethane diisocyanate) reacting with linear polyols

of the polyester and polyether families Various chain extenders, such

as glycols, water, diamines, or aminoalcohols, are used in either a polymer or a one-shot type of system to form the long-chain polymer.Recent formulations are more environmentally friendly, containingless solvent, more water, and less aromatic diisocyanates

pre-Textile fibers of urethane were first made in Germany under the

name of Igamide Flexible urethane fibers, used for flexible

gar-ments, are more durable than ordinary rubber fibers or filaments andare 30% lighter in weight They are resistant to oils and to washingchemicals, and also have the advantage that they are white

Spandex fibers are stretchable fibers produced from a fiber-forming

substance in which a long chain of synthetic molecules is composed of

a segmented polyurethane Stretch before break of these fibers isfrom 520 to 610%, compared to 760% for rubber Recovery is not asgood as in rubber Spandex is white and dyeable Resistance to chemi-cals is good, but it is degraded by hypochlorides

There are six basic types of polyurethane coatings, or urethane

coatings, as defined by the American Society for Testing and

Materials Specification D16 Types 1, 2, 3, and 6 have long storagelife and are formulated to cure by oxidation, by reaction with atmo-spheric moisture, or by heat Types 4 and 5 are catalyst-cured and areused as coatings on leather and rubber and as fast-curing industrialproduct finishes Urethane coatings have good weathering character-istics as well as high resistance to stains, water, and abrasion Tolimit emission of volatile organic compounds, there has been a trend

to waterborne and high-solids coatings

A biocompatible, polyurethane-based, shape-memory polymer,developed by Japan’s Mitsubishi Heavy Industries and available inthe United States from Memry Corp., undergoes dramatic changes inhardness, flexibility, elastic modulus, and vapor permeability withsmall temperature changes It has lower glass transition tempera-tures—standardized at 77°F (25°C), 95°F (35°C), 113°F (45°C), or

131°F (55°C)—than former memory polymers and far lower

tem-peratures than conventional thermoplastics Spoon handles, whichcan be heated and reformed to suit the deformed hands of handi-capped persons, is an early use Potential uses include medicalcatheters (stiff for insertion, flexible once implanted), custom-fittingorthopedic braces and splints, actuator mechanisms, and textile coat-ings whose permeability varies with temperature change

VALVE ALLOYS. Iron-, nickel-, and cobalt-base alloys are the cipal materials for intake and exhaust valves and valve-seat inserts

prin-of reciprocating combustion engines Requirements include tance to adhesive wear, heat, corrosion, and fatigue Intake valvesfor light-duty, lower-temperature service are made from plain car-bon steels Temperatures are generally less than 800°F (425°C) inlight-duty, spark-ignition engines and 930°F (500°C) in heavy-dutyones Low-alloy martensitic steels, high-alloy martensitic steels,and austenitic steels are used progressively as temperatures andpressures increase Intake-valve seats are commonly hard-facedwith a seat-facing alloy for the most demanding applications.Exhaust valves require resistance to wear, seat-face burning or gut-tering, fatigue, and creep, the last to prevent head doming or “tulip-ing.” Operating temperatures are generally 1300 to 1400°F (700 to760°C), with spikes as high as 1560°F (850°C) Exhaust valves are

typically made of austenitic stainless steels and, for the highestservice temperatures, superalloys.

Valve alloys include 1541H and 1547 carbon steels; 3140, 4140H, 5150H, 8645, B16, and GM-8440 low-alloy steels; Sil 1, Sil XB, 422, and SUH 11M martensitic stainless steels; and 21-2N, 21-4N, 21- 4N+Cb+W, 23-8N, Gaman H, and 302 HQ austenitic stainless

steels Among the superalloys, all nickel-base, are Inconel 751,

Nimonic 80A, Pyromet 31V, and Waspaloy Tensile yield strength at1200°F (650°C) is 8,300 lb/in2 (57 MPa) for 3140, 23,000 lb/in2 (160MPa) for Sil XB, 48,000 lb/in2(330 MPa) for 21-4N, and 125,000 lb/in2

(860 MPa) for Waspaloy The last also has a hot hardness of Brinell

240 Titanium alloys Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo find limited specialty applications Facing alloys include nickel-base Eatonite,

Eatonite 3 and 5, and X-782, and cobalt-base Stellite, 1, 6, 12, and

F and Tribaloy T400 and T800 All contain substantial chromium

and molybdenum and/or tungsten

Insert alloys, also iron-, nickel, or cobalt-base, require hot ness, corrosion resistance, heat resistance, resistance to adhesivewear, and film lubricity to reduce wear Performance stems largelyfrom the type and distribution of their carbide content The iron car-bides are the least wear resistant and thermally stable, molybdenumand tungsten M6C carbides are the best in these respects, and thechromium carbides are intermediate Only cobalt alloys are recom-mended for high-sulfur environments

hard-Iron-base alloys include M2 tool steel (W70V) and vanadium-free

M2, Sil XB (W90), W93, and W95 (W designations are those ofWinsert, Inc.) The tool steels, which contain M6C carbides, are moreresistant to wear and heat than W90, which contains iron andchromium carbides Hardness, 38 to 52 Rockwell C at room tempera-ture, falls only to 30 to 34.5 at 800°F (427°C) and to 23.5 to 25 at1000°F (538°C) In contrast, W90 is 35 to 45 at room temperature andfalls to 26.5 and 9, respectively The tool steels are often used forexhaust applications in gasoline engines and intake applications indiesel engines W90 is most often used for gasoline and diesel intakeand gasoline exhaust inserts W10 and W77T6 are Winsert propri-etary compositions intended to replace more costly Stellite andTribaloy cobalt alloys W10, used for severe sliding-wear applications,has an iron-base laves phase similar to that of Tribaloys but hasgreater hardness at 400 to 1000°F (204 to 538°C), due to forming aprecipitate that improves wear resistance Applications includeintake and exhaust inserts subject to temperatures as high as 1200°F(649°C) with natural gas and alcohol-base fuels, such as ethanol,methanol, and methane W77T6, for similar as well as heavy-dutydiesel applications, is a modified tool steel with refined carbides for

sliding-wear resistance Also, it forms a beneficial surface film forintake applications and is especially effective in high-speed opera-tions.

Nickel alloys, most often used for diesel exhaust inserts, include

W230, W240 (GM3550M), W250 (SAE J610B, 13), W260 (J610B, 12),W270, and W280 (Super Eatonite) W240 has a Rockwell C hardness

of 35 to 48 at room temperature, 37 at 800°F, 38.5 at 1000°F, 32 at1200°F, and 18 at 1400°F (760°C) W280 has the greatest Rockwell Chardness: 45 to 55 at room temperature, 44 at 1000°F, 41 at 1200°F,and 30 at 1400°F W210, a proprietary composition with greater ironcontent, is designed to replace more costly nickel alloys for dieselexhaust inserts All of these alloys are generally confined to exhaustapplications, performing poorly as intake alloys because, perhaps, ofthe type of film formed at lower temperatures

As a class, cobalt alloys are generally useful to somewhat higher

temperatures (1600°F, 871°C) and also provide sulfidation resistance.They include Stellite 3 (W100), W110 (MIL 15345, Alloy 21), Stellite 6(W120), Stellite 12 (W180), W150, and W170 Stellite 3 has 52%cobalt, 30.5 chromium, and 12.5 tungsten; W150 contains 60 cobalt,

28 molybdenum, and 8 chromium Both alloys have similar Rockwell

C hardness: 50 to 60 at room temperature and, respectively, 49.5 and51.5 at 800°F, 48.5 and 49.5 at 1000°F, 43 and 42.5 at 1200°F, and 30and 33 at 1400°F Tribaloy T400 has the advantage of the combinedlubricity and hardness of the laves phase for greater wear resistance

VANADIUM. An elementary metal, symbol V, widely distributed, butfound in commercial quantities in only a few places, chiefly Peru,Zimbabwe, southwest Africa, and the United States The commonores of vanadium are carnotite, patronite, roscoelite, and vanadinite.Much of the commercial vanadium comes from Peruvian patronite

and shales Some Russian vanadium comes from the mineral

tyuya-munite, the calcium analog of carnotite This analog also occurs in

American carnotite as a greenish-yellow powder Titaniferous ores ofSouth Africa also furnish vanadium But more than 60% of the knownresources are in the United States Carnotite occurs in Utah andColorado, and the Arizona ore is vanadinite The most important ore

in the United States is roscoelite It is a muscovite mica in which

part of the aluminum has been replaced by vanadium It occurs inmicalike scales varying in color from green to brown It has a specificgravity of 2.9 The ore mined in Colorado contains about 1.5% vana-dium oxide, V2O5, and this oxide is extracted and marketed for mak-ing ferrovanadium and vanadium compounds The slag from Idahophosphorus workings contains up to 5% vanadium, which is concen-trated to 13% and extracted as vanadium pentoxide It is recovered

from petroleum Venezuelan crude oil, containing 130 ppm vanadium,yields 2,000 lb (907 kg) of vanadium pentoxide per 1  106gal (3.79 

106L) of oil

Vanadium is a pale-gray metal with a silvery luster Its specificgravity is 6.02, and it melts at 3236°F (1780°C) It does not oxidize inair and is not attacked by hydrochloric or dilute sulfuric acid It dis-solves with a blue color in solutions of nitric acid It is marketed byVanadium Corp., 99.5% pure, in cast ingots, machined ingots, andbuttons The as-cast metal has a tensile strength of 54,000 lb/in2(372MPa), yield strength of 45,000 lb/in2(310 MPa), and elongation 12%.Annealed sheet has a tensile strength of 78,000 lb/in2 (538 MPa),yield strength 66,000 lb/in2(455 MPa), and elongation 20%, while thecold-rolled sheet has a tensile strength of 120,000 lb/in2 (827 MPa)with elongation of 2% Vanadium metal is expensive, but is used forspecial purposes such as for springs of high flexural strength and cor-rosion resistance The greatest use of vanadium is for alloying

Ferrovanadium, for use in adding to steels, usually contains 30 to

40% vanadium, 3 to 6 carbon, and 8 to 15 silicon, with the balanceiron, but may also be had with very low carbon and silicon

Vanadium-boron, for alloying steels, is marketed as a master alloy

containing 40 to 45% vanadium, 8 boron, 5 titanium, 2.5 aluminum,and the balance iron; but the alloy may also be had with no titanium

Van-Ad alloy, for adding vanadium to titanium alloys, contains 75%

vanadium and the balance titanium It comes as fine crystals The

vanadium-columbium alloys developed by Union Carbide,

contain-ing 20 to 50% columbium, have a tensile strength above 100,000 lb/in2

(690 MPa) at 1292°F (700°C), 70,000 lb/in2 (483 MPa) at 1832°F(1000°C), and 40,000 lb/in2(276 MPa) at 2192°F (1200°C)

Vanadium salts are used to color pottery and glass and as mordants

in dyeing Red cake, or crystalline vanadium oxide, is a reddish-brown material, containing about 85% vanadium pentox-

ide, V2O5, and 9 Na2O, used as a catalyst and for making vanadiumcompounds Vanadium oxide is also used to produce yellow glass; the

pigment known as vanadium-tin yellow is a mixture of vanadium

pentoxide and tin oxide

VANADIUM STEEL. Vanadium was originally used in steel as acleanser, but is now employed in small amounts, 0.15 to 0.25%, espe-cially with a small quantity of chromium, as an alloying element tomake strong, tough, and hard low-alloy steels It increases the tensilestrength without lowering the ductility, reduces grain growth, andincreases the fatigue-resisting qualities of steels Larger amounts areused in high-speed steels and in special steels Vanadium is a powerfuldeoxidizer in steels, but is too expensive for this purpose alone Steels

with 0.45 to 0.55% carbon and small amounts of vanadium are used forforgings, and cast steels for aircraft parts usually contain vanadium.

In tool steels vanadium widens the hardening range, and by the tion of double carbides with chromium makes hard and keen-edged die

forma-and cutter steels All of these steels are classified as

chromium-vana-dium steels The carbon-vanachromium-vana-dium steels for forgings and castings,

without chromium, have slightly higher manganese

Vanadium steels require higher quenching temperatures than

ordi-nary steels or nickel steels SAE 6145 steel, with 0.18% vanadium and

1 chromium, has a fine grain structure and is used for gears It has atensile strength of 116,000 to 292,000 lb/in2 (800 to 2,013 MPa) whenheat-treated, with a Brinell hardness of 248 to 566, depending on thetemperature of drawing, and an elongation of 7 to 26% In cast vana-dium steels it is usual to have from 0.18 to 0.25% vanadium with 0.35

to 0.45 carbon Such castings have a tensile strength of about 80,000lb/in2 (552 MPa) and an elongation of 22% A nickel-vanadium caststeel has much higher strength, but high-alloy steels with only smallamounts of vanadium are not usually classified as vanadium steels

VANILLA BEANS. The seed pods of a climbing plant of the orchid ily of which there are more than 50 known species It is native toMexico, but now also is grown commercially in Madagascar,Seychelles, Tahiti, Réunion, Mauritius, and tropical America It is

fam-used for the production of the flavor vanilla The species grown for

commercial vanilla is Vanilla planifolia, a tall climbing herb with

yel-low fyel-lowers It grows in humid, tropical climates The fyel-lowers are linated by hand to produce 30 to 40 beans per plant The green beansare cured immediately in ovens to prevent spoilage after a sweatingprocess During the curing the glucoside is changed by enzyme action

pol-into vanillin, which crystallizes on the surface and possesses the

characteristic odor and flavor The dark-brown cured pods are put up

in small packs in tin containers Vanillin also occurs naturally in

potato parings and Siam benzoin Vanilla extract is made by

percolating the chopped bean pods in ethyl alcohol, and then trating the mixture by evaporating the alcohol at a low temperature

concen-to avoid impairing the flavor

The species V pompana is more widely distributed, but is not as

fragrant The vanilla grown in Tahiti has an odor of heliotrope whichmust be removed At least 15 species of vanilla grow in the Amazonand Orinoco valleys Vanilla was used by the Aztecs for flavoringchocolate It is now used for the same purpose, and as a flavor for icecream, puddings, cakes, and other foodstuffs

Vanillin is also produced synthetically from eugenol derived from

clove oil, and from guaiacol obtained by the alkylation of catechol or

by the destructive distillation of wood It is also made from

coniferin, C16H22O8 2H2O, a white, crystalline material of meltingpoint 365°F (185°C) obtained from the sapwood of the northern pine

It is produced in Wisconsin from pulp-mill waste liquors by hydratinginto sugars and oxidizing to vanillin But the synthetic vanillin doesnot give the full, true flavor of vanilla, as a blend of other flavors ispresent in the natural product The demand for vanilla as a flavor isalways greater than the supply, so that even the grades rated as purevanilla extract may be so adulterated or diluted as to lose the full,rich flavor Vanillin is used as a chemical intermediate in the produc-

tion of pharmaceuticals, such as L-dopa, Trimethaprim, and

Aldomet.

Ethyl vanillate, C6H3(OH)(OCH)3(COOC2H5), is made fromWisconsin sulfite liquor It is used in cheese to prevent mold, and as a

preservative in tomato and apple juice Lioxin, of Ontario Paper Co.,

is an impure 97% vanillin made from sulfite lignin It is not suitablefor use as a flavor, but is used as an odor-masking agent, as a bright-ener in zinc-plating baths, as an antifoam agent in lubricating oils,

and for making syntans Veratraldehyde is obtained by methylating

vanillin and is used for brightening metals in the plating industry

Vanitrope, of Shulton, Inc., is a synthetic aromatic with a flavor 15

times more powerful than vanillin but with a resinous note bling that of coumarin It differs from vanillin chemically by having

resem-no aldehyde group, and is a propenyl guaethol related to eugeresem-nol.

It is used as a vanilla extender A blend of Vanitrope and vanilla,

called Nuvan, is used as a low-cost vanilla flavor Vanatone and

Vanarine, of Fritzsche Bros., Inc., are blends of vanillin with

aldehy-des and esters to increase the flavor tone

VAPOR-DEPOSITED COATINGS. Thin, single- or multilayer coatingsapplied to base surfaces by deposition of the coating metal from itsvapor phase Most metals and even some nonmetals, such as silicon

oxide, can be vapor-deposited Vacuum-evaporated films, or

vac-uum-metallized films, of aluminum are most common They are

applied by vaporizing aluminum in a high vacuum and then allowing

it to condense on the object to be coated Vacuum-metallized films areextremely thin, ranging from 0.002 to 0.1 mil (0.00005 to 0.003 mm)

In addition to vacuum evaporation, vapor-deposited films can be

pro-duced by ion sputtering, chemical-vapor plating, and a

glow-dis-charge process In ion sputtering, a high voltage applied to a target of

the coating material in an ionized gas medium causes target atoms

(ions) to be dislodged and then to condense as a sputtered coating on

the base material In chemical-vapor plating, a film is deposited when

a metal-bearing gas thermally decomposes on contact with the heated

1006 VAPOR-DEPOSITED COATINGS

surface of the base material And in the glow-discharge process,applicable only to polymer films, a gas discharge deposits and poly-

merizes the plastic film on the base material In recent years,

tita-nium nitride, deposited by chemical vapor deposition or physical

vapor deposition, has been used to markedly increase the wear tance of cutting tools and forming tools made of tool steels

resis-VARNISH. A solution of a resin in drying oil, which when spread out

in a thin film dries and hardens by evaporation of the volatile solvent,

or by the oxidation of the oil, or by both A smooth, glossy coating isleft on the surface Varnishes do not contain pigments; when mixedwith pigments, they become enamels The most commonly used resin

is ordinary rosin, and the most common drying oils are linseed and

tung oils Spirit varnishes are those in which a volatile liquid, such

as alcohol or ether, is used as a solvent for the resin or oil They dry

by the evaporation of the solvent Oleoresinous varnishes are those

in which the resin is compounded with an oxidizable oil, such as seed oil The gums used in varnish, such as copal, dammar, and

lin-kauri, produce hardness and gloss to the film, and the fossil resins,

such as kauri, give greater hardness and luster to varnishes than dothe natural resins The oils, such as tung and linseed, make it elasticand durable

Other important ingredients of varnishes are driers, such as ganese oxide, to hasten the action of the drying oil, and thinningagents, or reducers, such as turpentine, naphtha, and benzol.Hydrated lime is added to varnishes to neutralize the acid in theresin, and to clarify and harden the varnish to prevent it from becom-

man-ing sticky in warm weather Spar varnishes are those made to stand weather conditions Gloss oil is a solution of hardened rosin in

with-benzene or in turpentine with sometimes a small amount of tung oil

to give a tougher film It gives a high gloss but is not durable Long

varnishes are those containing 20 to 100 gal (76 to 379 L) of oil to

100 lb (45 kg) of resin; a short varnish is one with less oil The short

varnishes are hard and glossier, but not as flexible or durable.Ordinarily, quick-drying varnish made with a natural resin is lessdurable than slow-drying; hardness and gloss are not guarantees ofgood varnish

Varnish was originally only a colorless or nearly colorless coatingmaterial for furniture and fancy wood products to give a smooth, glossysurface for protection and to bring out the texture of the wood, and

marine varnish was a high grade of spar varnish Any color used was

merely to accent the original color of the wood or to imitate the color of

another wood of similar grain Phenol-formaldehyde varnish is

noted for all-round resistance to weathering under marine conditions

The finish has a tendency to yellow with age and lose gloss, but the

varnish rarely cracks, peels, or chips Sometimes called bakelite

var-nish because of its resistance to caustic and acid materials, the varvar-nish

can be washed with soap without impairing the finish Modified

phe-nolic varnishes are hard and abrasion-resistant, but are more

suscep-tible to weathering They are suitable for floors, furniture, and toys

Short-oil types may be used for rubbing varnish Insulating

var-nishes were colorless varvar-nishes for protecting drawings, paintings,

and other products from moisture, or for electrical insulating But the

term varnish has come to mean any light-bodied, quick-drying, glossy

finish as distinct from heavily pigmented, glossy enamels Synthetic

varnishes may now contain synthetic resins in oils, or they may be

made entirely with synthetic resins in solvents These include bondingand impregnating varnishes, based mainly on alkyd, acrylic, vinyl,epoxy, urethane, amino, and polyester resins Soybean oil is used in themanufacture of oil-modified alkyd resin varnish, and safflower and

sunflower oils in color-retentive urethane varnishes Electrical

var-nishes are likely to be silicone, epoxy, or polyester resins that give good

dielectric strength and adhesion

VEGETABLE FATS. When specifically used, the term refers larly to semisolid vegetable oils that are used chiefly for food.Vegetable oils and fats usually contain only small quantities of thefat-soluble vitamins A, D, and E, and after refining, they are usuallydevoid of vitamins Thus, they are a better food in the producingcountries Climate in which the plant is grown has an effect on thenature of the oils Warm climates favor the development of oleic acidwhile colder climates favor the less palatable linolenic acid The low-melting-point oils are more easily assimilated in the body, butwhen these are hydrogenated to a melting point above 113°F (45°C),they become difficult to assimilate Most of the more edible vegetablefats, as distinct from the more liquid food oils, are tropical products

particu-Suari fat is a hard, white fat with a pleasant taste obtained from the

kernels of the seeds of Caryocar brasiliense and other species of

tropi-cal America The kernels yield 60 to 70% fat of a specific gravity of0.989, melting point 86 to 99°F (30 to 37°C), and iodine value 41 to

50 Ucuhuba tallow, used in soaps and for candles, is a fat from the

seeds of the trees Virola surinamensis and V sebifera of Brazil The

seeds yield about 65% fat, but the extraction with petroleum etheralso removes resinous material The tallow has an iodine value of 10

to 15 and a melting point between 109 and 122°F (43 and 50°C)

Mahuba fat is a hard, edible fat from the fruit of the tree

Acrodicilidium mahuba of Brazil Gamboge butter, known locally as

gurgi and murga, is from the seeds of the fruit of the trees Garcinia

morella, G hanburii, and other species of Sri Lanka and India The

melting point is 93 to 99°F (34 to 37°C), specific gravity 0.90 to 0.913,and saponification value 196 It is used as a soap and food oil, andlocally as an illuminant and an ointment From these trees also

comes the gum resin gamboge used in medicine as a cathartic, and

also used as a brown dyestuff It is alcohol-soluble

Sierra Leone butter, also called kanga or lamy, is a pale-yellow

fat from the seeds of the fruit of the tree Pentadeama butyracea of

west Africa The melting point is about 104°F (40°C), specific gravity0.857 to 0.860, saponification value 186 to 198, and iodine number

around 60 It is a soap oil Mafura tallow is a bitter-tasting, heavy

fat from the nuts of the tree Trichilia emitica of east Africa It is used

for soap, candles, and ointments The specific gravity is 0.902,

melt-ing point about 104°F, and saponification value 201 Shea nut oil, also known as shea butter, Bambuk butter, Galam butter, and by various local names as karité, kade, and kedempó, is a fat obtained

from the kernels of the fruit of the large tree Bassis butyrospermum

of tropical west Africa The kernels contain 45 to 55% fat, which whenrefined is white, stiffer than lard, with little odor or taste The melt-ing point is 91 to 108°F (33 to 42°C) It contains oleic and stearic acidsand 3 to 4% lauric acid It is used in Europe in butter substitutes, as

a substitute for cocoa butter, and in candles Malabar tallow, also called dhupa fat and piney tallow, used in Europe for soap and can-

dles and in India for food, is from the kernels of the seed of the

ever-green pinne tree, Vateria indica of south India The tree also yields

white dammar or Indian copal The seeds give about 25% of a greenish-yellow, odorless, and tasteless fat of specific gravity 0.890,melting point 104°F, and saponification value 190 The fat isextracted by grinding the roasted seed, boiling in water, and skim-ming off It is bleached by exposure

Vegetable tallow, also called bayberry tallow, capeberry wax, laurel wax, and myrtle wax, used extensively in Europe for soap-

making and in the United States for blending in candles and withwaxes, and for polishing leathers, is a waxy fat obtained from the out-

side coating of the berries of species of Myrica bushes of America,

Europe, and Africa by boiling the berries in water The berries yield 15

to 25% tallow The species M cerifera and M carolinensis grow in the eastern coastal states, and M mexicana grows in Central America.

The melting point of the tallow is 104 to 115°F (40 to 46°C), specificgravity 0.995, and saponification value 205 to 212 The CentralAmerican product contains about 58% myristic acid, 36 palmitic acid,

and 1.3 oleic acid Ocuba wax is a waxy fat, but not chemically a wax,

obtained from the seeds of the fruit of the shrub Myristica ocuba of

Brazil The seeds yield about 20% fat with a specific gravity of 0.920

and melting point of 104°F, which is used in candles The fruit nut issurrounded by a thick skin which yields a water-soluble pink dye

known as ocuba red.

Mahubarana fat is a pale-yellow, solid oil of melting point 104 to

111°F (40 to 44°C) obtained from the kernels of the fruit of trees of the

genus Boldoa The kernels contain 65% oil, which is used for soaps

and candles Mocaya butter is a fat from the kernels of the nuts of

the Paraguayan palm, Acrocomia sclerocarpa, of tropical South

America The tree resembles a coconut palm, but the nuts grow inbunches The pulp of the fruit contains 60% of a yellow oil similar topalm oil The kernels yield 53 to 65% of the mocaya fat, which issofter than palm kernel oil The specific gravity is 0.865, and saponifi-cation value 240 It has the same uses as palm kernel oil

VEGETABLE OILS. An important class of oils obtained from plants,used industrially as drying oils, for lubricants, in cutting oils, fordressing leather, and for many other purposes Many of the oils findwide usage in food products Large tracts of land are under cultiva-tion in all parts of the world for the production of the seeds and fruits

from which the oils are obtained Linseed, cottonseed, palm, olive, and castor beans are examples of these, and the oils are obtained by

crushing In some cases the oil-bearing material, copra or soybean,may be dehydrated before crushing, making it simpler to extract theoil, and giving a better residue meal for animal feed The chief dis-tinction between vegetable oils and fats is a physical one, oils being

fluid at ordinary temperatures Aceituno oil from the seeds of the

Central American plant Simarouba glauca is a borderline vegetable

oil due to its consistency, and it can be easily converted into a etable fat by slight hydrogenation Vegetable oils can be thickened forvarious uses by oxidation, by blowing air through them, or they can

veg-be solidified by hydrogenation

In the making of plastics and chemicals from fatty acids derivedfrom vegetable oils, the cost of the oil may be as much as 50% of thefinal cost of the product, and price plays an important part in thechoice of raw material Oils produced in countries subject to politicaland economic disturbances may have sudden and great price fluctua-

tions Thus, domestic soybean oil may be substituted for castor oil in

making nylon even though more chemical operations are needed, orthe acids may be synthesized from petroleum hydrocarbons

Food oils are chosen by their content of essential fatty acids, but

taste is an important factor Linseed oil is not used for food in theUnited States, although it has high food value and contains both

linoleic and linolenic acids Safflower oil, high in linoleic acid, ranks

high as a food oil, only 0.003 lb (1.35 g) of oil being required to provide

0.002 lb (1 g) of essential fatty acids Olive oil, high in oleic acid withonly one double bond, requires 0.031 lb (14.2 g) of oil for 0.002 lb ofessential acid But olive oil requires less linoleic acid to counteract itseffect than an equivalent amount of a saturated acid with no doublebond Butter requires the consumption of 0.04 lb (20 g) to obtain

0.002 lb of essential acids, while soybean, corn, and cottonseed oils,

used in margarine, rank high as food oils

Considerable oil is extracted from the kernels of the stones or pits

of cherries, apricots, and other fruits as a by-product of the canning

and drying of fruits Cherry kernel oil is from cherry pits which

contain 30 to 38% oil The cold-pressed oil is yellow and has a ant flavor It is used in salad oils and in cosmetics The hot-pressed oil

pleas-is used in soaps The oil contains 47% oleic acid, 40 linoleic, 4

palmitic, 3 stearic, and some arachidic and myristic acids Apricot

kernel oil and almond oil have similar properties and applications Grapeseed oil is obtained by pressing the by-product grape seeds

from the wine industry The seeds contain 10 to 15% oil, valued inEurope as an edible oil, but used in the United States mostly forpaints and soaps The oil contains about 52% linoleic acid, 32 oleicacid, and palmitic, stearic, and arachidic acids The hot-pressed oil isdark green and not sweet, but the cold-pressed, refined oil is colorless

and has a nutlike taste Another name for grapeseed oil is raisin

seed oil Tomato seed oil is from the seeds of the tomato,

Lycopersicon esculentum, the seeds being by-products of the

manufac-ture of tomato juice and tomato puree, vast quantities of which

are produced in the United States from pulp The tomato plant is aperennial native to Central and South America, and was grown by the

Aztecs under the name of tomatl There are many varieties, and the

fruits are true berries The common red varieties are 2 to 3 in (5 to 8cm) in diameter and contain a large number of seeds in the pulp Theseeds yield 17% oil by cold pressing, or 33% by solvent extraction Thecold-pressed oil is a clear liquid of 0.920 specific gravity, with anagreeable odor and bland taste The iodine number is 113, andsaponification value 192 It is used in salad oils, margarine, soaps,and as a semidrying oil for paints

VELVET. A closely woven silk fabric with a short pile on one sideformed by carrying the warp threads over wires and then cuttingopen the loops Velvet is made in a great variety of qualities andweights, and it may have a cotton back in the cheaper grades or bemade in wool True velvet is all silk; but because of the number ofimitations in other materials, this variety is usually designated as

silk velvet Velvet is dyed in various colors, the depth of color

shown by the pile, giving it an air of richness Its largest use is in

dress goods and hangings, but it is used industrially for upholstery,fancy linings, and trim.

Plush is a name for fabrics woven of cotton, silk, linen, or wool,

having a pile deeper than that of velvet It is used for upholstery.Originally the pile of plush consisted of mohair or worsted yarns, but

there is now no distinction except in the length of the pile

Uphol-stery plush is made in brocade designs by burning the pile with

rollers to form a lower background Plush is also dyed and curled toimitate furs

Velveteen is an imitation velvet, woven of cotton In the best

grades, the pile is of mercerized yarns Velveteen is woven into twosystems of filling yarns and one system of warp yarns, the pile beingmade with the cut filling yarns instead of the warp yarns, as in vel-

vet It belongs to the class of fustians which also includes moleskin and corduroy The latter is a sturdy pile fabric with heavy warp rib,

dyed in the piece It is also made in wool The ribs run lengthwise,

while whipcord, a hard-woven worsted fabric, has fine ribs running

diagonally on the face Velveteen is used for apparel, linings for elry and silverware boxes, shoe uppers, artificial flowers, and cover-ing material It is made either plain back or twill back, the plain backhaving a tendency to loosen and drop the pile

jew-VERMICULITE. A foliated mineral employed in making plasters andboard for heat, cold, and sound insulation, as a filler in caulking com-pounds, and for plastic mortars and refractory concrete The mineral

is an alteration product of biotite and other micas, and is found in

Colorado, Wyoming, Montana, and the Transvaal It occurs in talline plates, specific gravity 2.3, and Mohs hardness 1.5, measuringsometimes as much as 9 in (23 cm) across and 6 in (15 cm) in thick-ness The color is yellowish to brown Upon calcination at 1750°F(954°C), vermiculite expands at right angles to the cleavage intothreads with a vermicular motion like a mass of small worms; henceits name The volume increases as much as 16 times, and the colorchanges to a silvery or golden hue It is ground into pellet form.Plaster made with 60% vermiculite, 30 plaster of paris, and 10

crys-asbestos will withstand red heat without disintegrating

Therm-O-Flake brick is made of granules of exfoliated vermiculite bonded

with a chemical It is lightweight, tough, and withstands tures to 2000°F (1093°C) The corklike pellets of vermiculite used for

tempera-insulating fill in house walls are called mica pellets Zonolite, of W.

R Grace & Co., is an exfoliated vermiculite Zonolite Verxite, of the same company, is a spongy, granular powder form of Verxite, a ther-

mally expanded vermiculite It is used as a blending agent in animal

feeds A sound-absorbing building tile, called Rockoustile, is made of

exfoliated mica An expanded vermiculite of extremely fine mesh,

under the name of Mikolite, is used as an extender in aluminum paint and in lubricating oils Exfoliated mica is a name for expanded vermiculite Terra-Lite is fluffy, powdered vermiculite for

conditioning soils It holds water, prevents soil crusting, and helps tomaintain soil temperature below the critical 80°F (27°C)

VINYL RESINS. A group of products varying from liquids to hardsolids, made by the polymerization of ethylene derivatives, employedfor finishes, coatings, and molding resins; or it can be made directly

by reacting acetic acid with ethylene and oxygen In general, the term

vinyl designates plastics made by polymerizing vinyl chloride, vinyl

acetate, or vinylidene chloride, but may include plastics made fromstyrene and other chemicals The term is generic for compounds of thebasic formula RCH:CR´CR″ The simplest are the polyesters of vinylalcohol, such as vinyl acetate This resin is lightweight, with a spe-cific gravity of 1.18, and is transparent, but it has poor molding quali-ties and its strength is no more than 5,000 lb/in2 (34 MPa) But thevinyl halides, CH2:CHX, also polymerize readily to form vinylite

resins, which mold well, have tensile strengths to 9,000 lb/in2 (62MPa), high dielectric strength, and high chemical resistance; and awidely useful range of resins is produced by copolymers of vinylacetate and vinyl chloride

Vinyl alcohol, CH2:CHOH, is a liquid boiling at 95.9°F (35.5°C)

Polyvinyl alcohol is a white, odorless, tasteless powder which on

drying from solutions forms a colorless, tough film The material isused as a thickener for latex, in chewing gum, and for sizes and adhe-sives It can be compounded with plasticizers and molded or extruded

into tough and elastic products Hydrolyzed polyvinyl alcohol has

greater water resistance and higher adhesion, and its lower residual

acetate gives lower foaming Soluble film, for packaging detergents

and other water-dispersible materials to eliminate the need to openthe package, is a clear polyvinyl alcohol film Textile fibers are alsomade from polyvinyl alcohol, either water-soluble or insolubilizedwith formaldehyde or another agent Polyvinyl alcohol textile fiber ishot-drawn by a semimelt process and insolubilized after drawing Thefiber has a high degree of orientation and crystallinity, giving goodstrength and hot-water resistance

Vinyl alcohol reacted with an aldehyde and an acid catalyst

pro-duces a group of polymers known as vinyl acetal resins, and

sepa-rately designated by type names, as polyvinyl butyral and polyvinyl

formal The polyvinyl alcohols are called Solvars, and the polyvinyl acetates are called Gelvas The vinyl ethers range from vinyl

methyl ether, CH2:CHOCH3, to vinyl ethylhexyl ether, from soft

compounds to hard resins Vinyl ether is a liquid which polymerizes,

or can be reacted with hydroxyl groups to form acetal resins Alkyl

vinyl ethers are made by reacting acetylene with an alcohol under

pressure, producing methyl vinyl ether, ethyl vinyl ether, or

butyl vinyl ether They have reactive double bonds which can be

used to copolymerize with other vinyls to give a variety of physical

properties The polyvinyl formals, Formvars, are used in molding

compounds, wire coatings, and impregnating compounds It is one ofthe toughest thermoplastics

A plastisol is a vinyl resin dissolved in a plasticizer to make a

pourable liquid without a volatile solvent for casting The poured

liq-uid is solidified by heating Plastigels are plastisols to which a gelling agent has been added to increase viscosity The polyvinyl

acetals, Alvars, are used in lacquers, adhesives, and phonograph

records The transparent polyvinyl butyrals, Butvars, are used as

interlayers in laminated glass They are made by reacting polyvinyl

alcohol with butyraldehyde, C3H7CHO Vinal is a general name for

vinyl butyral resin used for laminated glass

Vinyl acetate is a water-white, mobile liquid with boiling point

158°F (70°C), usually shipped with a copper salt to prevent ization in transit The composition is CH3:COO:CH:CH2 It may bepolymerized in benzene and marketed in solution, or in water solu-tion for use as an extender for rubber, and for adhesives and coatings.The higher the polymerization of the resin, the higher the softening

polymer-point of the resin The formula for polyvinyl acetate resin is given

as (CH2:CHOOCCH3)x It is a colorless, odorless thermoplastic with aspecific gravity of 1.189, unaffected by water, gasoline, or oils but sol-uble in the lower alcohols, benzene, and chlorinated hydrocarbons.Polyvinyl acetate resins are stable to light, transparent to ultravioletlight, and valued for lacquers and coatings because of their highadhesion, durability, and ease of compounding with gums and resins.Resins of low molecular weight are used for coatings, and those ofhigh molecular weight for molding Vinyl acetate will copolymerizewith maleic acrylonitrile, or acrylic esters With ethylene it produces

a copolymer latex of superior toughness and abrasion resistance forcoatings

Vinyl chloride, CH2CHCl, also called ethenyl chloride and

chloroethylene, produced by reacting ethylene with oxygen from air

and ethylene dichloride, is the basic material for the polyvinyl

chlo-ride resins It is a gas The plastic was produced originally in

Germany under the name of Igelite for cable insulation and as

Vinnol for tire tubes The tensile strength of the plastic may vary

from the flexible resins with about 3,000 lb/in2 (21 MPa) to the rigidresin with a tensile strength to 9,000 lb/in2(62 MPa) and Shore hard-