Coatings Technology Handbook Episode 1 Part 10 pptx

32 Cathodic Arc Plasma Deposition 32.1 Introduction ...32-1 32.2 Cathodic Arc Plasma Deposition Process ...32-1 32.3 Cathodic Arc Sources...32-3 32.4 Cathodic Arc Emission Characteristic

Trang 2

31-30 Coatings Technology Handbook, Third Edition

42 A Etspuler and H Suhr, J Appl Phys., A48, 373 (1989).

43 E Feurer, S Kraus, and H Suhr, J Vac Sci Technol., A7, 2799 (1989).

44 H Holzschuh and H Suhr, J Appl Phys., A51, 486 (1990).

45 H Holzschuh and H Suhr, Appl Phys Lett., 59, 470 (1991).

46 M D Hudson, C Trundle, and C J Brierly, J Mater Res., 3, 1151 (1988).

47 R A Kant and G K Huber, Surf and Coat Technol., 51, 247 (1992).

48 R Prange, R Cremer, D Neuschutz, Surf and Coat Technol, 133–134, 208–214 (2000).

49 E Kubel, Metall Powder Rep., 43, 832 (1988).

50 B Leon, A Klumpp, M Perez-Amor, and H, Sigmund, Appl Surf Sci., 46, 210 (1990).

51 Y S Liu, in Tungsten and Other Refractory Metals for VLSI Applications R L Blewer, Ed., Mater Res Soc Proc., 43 (1985).

52 C Mitterez, M Rauter, and P Rodhammer, Surf and Coat Technol., 41, 351 (1990).

53 S Motojima and H Mizutani, Appl Phys Lett., 54, 1104 (1989).

54 A Chayahara, H Yokoyama, T Imura, and Y Osaka, Appl Surf Sci., 33/34, 561 (1988).

55 C Oehr and H Suhr, J Appl Phys., A49, 691 (1989).

56 D Hofmann, S Kunkel, H Schussler, G Teschner, R Gruen, Surf and Coat Technol, 81, 146–150

(1996)

57 R D Arnell, Surf and Coat Technol., 43/44, 674 (1990).

58 E Bergmann, E Moll, in Plasma Surface Engineering, Vol 1 E Broszeit, W Muenz, H Oechsner,

G Wolf, Eds, Heidelberg: DGM-Verlag, Oberursel, 1989, p 547

DK4036_C031.fm Page 30 Thursday, May 12, 2005 9:40 AM

Trang 3

32 Cathodic Arc Plasma

Deposition

32.1 Introduction 32-1 32.2 Cathodic Arc Plasma Deposition Process 32-1 32.3 Cathodic Arc Sources 32-3 32.4 Cathodic Arc Emission Characteristics 32-3 32.5 Microdroplets 32-4 32.6 Recent Developments 32-5 References 32-7

32.1 Introduction

The cathodic arc plasma deposition (CAPD) method1,2 of thin film deposition belongs to a family of ion plating processes that includes evaporative ion plating3,4 and sputter ion plating.5,6 However, the CAPD process involves deposition species that are highly ionized and posses higher ion energies than other ion plating processes All the ion plating processes have been developed to take advantage of the special process development features and to meet particular requirements for coatings, such as good adhesion, wear resistance, corrosion resistance, and decorative properties

The cathodic arc technique, having proved to be extremely successful in cutting tool applications, is now finding much wider ranging applications in the deposition of erosion resistance, corrosion resistance, decorative coatings, and architectural and solar coatings

32.2 Cathodic Arc Plasma Deposition Process

In the CAPD process, material is evaporated by the action of one or more vacuum arcs, the source chamber, a cathode and an arc power supply, an arc ignitor, an anode, and substrate bias power supply Arcs are sustained by voltages in the range of 15 to 50 V, depending on the source material; typical arc currents in the range of 30 to 400 A are employed When high currents are used, an arc spot splits into multiple spots on the cathode surface, the number depending on the cathode material This is illustrated spots move randomly on the surface of the cathode, typically at speeds of the order of tens of meters per second The arc spot motion and speed can be further influenced by external means such as magnetic fields, gas pressures during coatings, and electrostatic fields

Materials removal from the source occurs as a series of rapid flash evaporation events as the arc spot migrates over the cathode surface Arc spots, which are sustained as a result of the material plasma generated by the arc itself, can be controlled with appropriate boundary shields and/or magnetic fields

H Randhawa

Vac-Tec Systems, Inc.

DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM

material being the cathode in the arc circuit (Figure 32.1) The basic coating system consists of a vacuum

in Figure 32.2 for a titanium source In this case, an average arc current/arc spot is about 75 A The arc

Trang 4

32-6 Coatings Technology Handbook, Third Edition

FIGURE 32.5 Microdroplet emission from metals having different melting points.

FIGURE 32.6 Scanning electron micrographs showing surface topography of various films using modified arc technology.

Cu

Ta

Cr

1.50 kv 30 kv 002

30 kv 014 1.00 kv

1.50 kv 30 kv 003 DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM

Trang 5

33 Industrial Diamond and

Diamondlike Films

33.1 Introduction 33-1 33.2 Diamond and Diamondlike Films 33-1 33.3 Film Deposition Techniques 33-2

33.4 Diamond and Diamondlike Film Properties 33-3 33.5 Potential Applications 33-4

The mechanical, electrical, thermal, and optical properties of diamond make it attractive for use in a variety of different applications ranging from wear-resistant coatings for tools and engineered compo-nents to advanced semiconductor structures for integrated circuit devices.1 Until recently, diamond

“coating” was done by bonding single-crystal diamond grits to the surfaces of the components to be coated Applications for diamond coatings were limited, therefore, to tooling used for cutting and grinding operations

Recent advancements in plasma-assisted chemical vapor deposition (PACVD) and ion beam enhanced deposition technologies make it possible to form continuous diamond and diamondlike carbon films on component surfaces There new films have many of the mechanical, thermal, optical, and electrical properties of single-crystal diamond, and they make possible the diamond facing of precision tools and wear parts, optical lenses and components, and computer disks, as well as the production of advanced semiconductor devices The most flexibility, in terms of properties of the deposited diamond films and types of material coatable, is found when the films are formed using ion beam deposition techniques

33.2 Diamond and Diamondlike Films

The ability to diamond-coat tools and engineered components required that diamond precursor material

be condensed from a vapor phase as a continuous film onto the surface of the component to be coated Furthermore, the deposition must proceed so that the vapor-deposited material condenses with the structure and morphology of diamond Diamond is a metastable form of carbon; as such, when con-densed from a vapor or from a flux of energetic particles, it will tend to assume its most thermodynam-ically stable state or form — graphite With advanced processes like chemical vapor deposition (CVD) and ion beam enhanced deposition, it is possible to influence, to a certain degree, the energy and charge states of the particles in the vapor phase, thus allowing some control over the energy state (stable or metastable) and crystallographic and stoichiometric form of the deposited films Thus, it is feasible to

Arnold H Deutchman

BeamAlloy Corporation

Robert J Partyka

BeamAlloy Corporation

Plasma-Assisted Chemical Vapor Deposition (PACVD)

References 33-5

Trang 6

17 O Matsumoto et al., Thin Solid Films, 146, 283 (1986)

18 N Fujimori et al., Vacuum, 36, 99 (1986)

19 S Aisenberg et al., J Appl Phys., 42, 2953 (1976)

20 E G Spenser et al., Appl Phys Lett., 29, 228 (1976)

21 J H Freeman et al., Nuclear Instrum Methods, 135, 1 (1976)

22 T Miyazawa et al., J Appl Phys., 55, 188 (1984)

23 J W Rabalais et al., Science, 239, 623 (1988)

24 C Weissmantel, Thin Solid Films, 92, 55 (1982)

25 M J Mirtich et al., Thin Solid Films, 131, 245 (1985)

26 C Weissmantel et al., J Vac Sci Technol A4, 6, 2892 (1985)

27 A H Deutchman et al., Ind Heating, LV(7), 12 (1988)

Trang 7

34 Tribological Synergistic

Coatings

34.1

34.2 What Are Synergistic Coatings? 34-2 34.3 Wear Testing 34-3 34.4 Coating Families 34-3

The solution of wear and many related problems for any application is very much experience dependent

A scientific basis for resolving these problems unfortunately has not yet been found Using experience and history, it is possible to recommend a number of potential solutions; however, the ultimate proof is

in the actual trial of the application This is because there are so many variables within each application that the slightest change could make a difference in the selection of the appropriate coating Even though applications appear to be identical, there are always slight differences such that the same coating selection will not always perform in the same manner

The production of synergistic coatings on steel (Nedox) or aluminum (Tufram) is based on the principle of infusion of a dry lubricant or polymer into the coatings General Magnaplate has developed

a family of such coatings (Nedox), each one representing specific properties, such as hardness, lubricity, corrosion protection, and dielectric strength The standard hardfacing for steel is an electroless nickel coating There are a number of electroless nickels that vary the phosphorus content and consequently have differences in hardness and corrosion resistance Choice of such a coating varies and is based on the application requirements

Synergistic coatings for aluminum (Tufram) have been used successfully for many years The system can accommodate almost all aluminum alloys, provided a copper content of 5% and a silicon content

of 7% are not exceeded Higher percentages of these constituents (set up too great a change in substrate resistivity, hence) prevent the buildup of required film thickness

The prime purpose of the Tufram system is to produce films having properties such as improved wear resistance, better surface release (lower coefficient of friction), good corrosion resistance, and high dielectric strength

The principle of these coatings is based on a hardcoat after which a polymer or dry lubricant is infused into the coating substrate

All coatings are used in a wide variety of industries Some are in compliance with the regulations of the U.S Food and Drug Administration and can be used in food and medical applications

Walter Alina

General Magnaplate Corporation

Introduction 34-1

Trang 8

Tribological Synergistic Coatings 34-5

TABLE 34.1 Friction Data by Materials

Upper Plate a Lower Plate a

Coefficients of Friction Static Kinetic

Magnaplate TFE Magnagold + TFE 0.225 0.174

Trang 9

Graphite over paper Graphite over paper 0.322 0.302

Hardcoated aluminum Hardcoated aluminum 0.264 0.220

TABLE 34.1 Friction Data by Materials (Continued)

Coefficients of Friction Static Kinetic DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM

Trang 10

a A superscript “a” indicates additional polish after coating; a “b” indicates postburnishing — comparable to breaking in the surface.

TABLE 34.2

Designation in

Aluminum 6061 T6 grade (0.250) thickness

Steel 1032 grade H32 (0.250) thickness

Titanium A 6A1/4V (0.250) thickness

Titanium P Vacuum deposited at 10 to 5 torr, 2 µ m thickness, purity 99.99%

Glass Tempered (0.250) thickness

Teflon White, virgin grade (0.250) thickness

Nickel Autocatalytic 6/8% phosphorus (0.001)

Hard chromium Industrial grade (0.0003)

Hard anodize 6061 T6 (0.002)

Tufram Proprietary aluminum coating

Nedox Proprietary treatment for steel and stainless steels and nonferrous metals

Hi-T-Lube Proprietary solid film metal alloy lubricant

Magnagold Proprietary method for vacuum coating of titanium nitride

Magnaplate HMF Proprietary ultrahard, high microfinish for most base metals

Magnaplate HCR Proprietary ultrahard and exceptionally corrosion-resistant coating for aluminum

FIGURE 34.2 T.M.I slip and friction tester.

TABLE 34.1 Friction Data by Materials (Continued)

Coefficients of Friction Static Kinetic DK4036_book.fm Page 7 Monday, April 25, 2005 12:18 PM

Key to Materials and Coatings Listed in Table 34.1

Trang 11

surface preparation A combination of specialty designed equipment and chemical cleaning techniques prepares the component surface to assure permanently interlocked anchoring of the “coating.” Conven-tional vapor deposition applicators are not equipped with the extensive facilities that permit the meticulous care and attention required in the precleaning phase of the process The parts are mounted on a specially designed cylindrical fixture, and then the entire work cylinder enters the vacuum chamber A vacuum (1

× 10–6 torr) is achieved, after which the system is purged with argon gas as an additional cleaning step Titanium metal (99.9%) is then vaporized by a plasma energy source This is followed by the precise introduction of nitrogen, the reactive gas, into the chamber The parts to be coated are cathodically charged

by high voltage (dc), thereby attracting accelerated ions of titanium Simultaneously, they combine with nitrogen to produce the tightly adhering, highly wear-resistant titanium nitride PVD coating

FIGURE 34.3 The Taber Abraser.

FIGURE 34.4 Weight loss following Taber abrasion for aluminum samples with various coatings.

10

Hardcoat Anodized (Sealed) Per MIL-A-8625 Type III, Class 1

Hardcoat Anodized (Unsealed) Per MIL-A-8625 Type III, Class 1

19 mg.

42 mg.

4 mg.

Magnaplate HCR Coating

Weight Loss = mg Per 10,000 Cycles, CS-17 Wheel, 1000 gm Load

Taber Abrasion (Aluminum)

Trang 12

Note: Some alloys are sensitive to temperatures up to 900°F and can be reduced in hardness if the substrate material selected is not heat compatible with this process It is possible to lower processing temperature to prevent certain steels from annealing; however, there may be a slight reduction in the hardness of the titanium nitride coating

FIGURE 34.5 Weight loss following Taber abrasion for steel samples with various coatings.

TABLE 34.3 Some Physical Properties of Magnagold Coatings

Chemical resistance to 30% concentrations of nitric and sulfuric acids on copper and steel substrates at ambient temperature

Virtually no attack

Taber abrasion test, CS 10 wheel, 1000 g load, 10,000 cycles

Average weight loss >0.5 mg

Uniformity of thickness 15 × 10 –5 0.000015 in (max.) Crystal lattice Body-centered cubic, a= 4.249 ô

Thermal conductivity, cal/cm/sec/ ° C ~0.162 (at 1500 ° C)

~0.167 (at 1600 ° C)

~0.165 (at 1700 ° C)

~0.136 (at 2300 ° C) Coefficient of thermal expansion × 10 –6 cm/ ° C 9.35 ± 0.04 (at 25 ~1100 ° C) Electrical resistivity 40 µΩ (at 27 ° C)

Thermonic emission work function 3.75 eV Microhardness (Hu) 2050 kg/mm 2 (load 100 g)

10

mg 20 30 40 50 60 70 80 90 100 110 120 130 140

73.5 mg.

134.4 mg.

27.7 mg.

31 mg.

Taber Abrasion (Steel)

Electroless Nickel Per Mil-C-26074 Class 1 (0.001 — No Heat Treatment)

Electroless Nickel Per Mil-C-26074 Class 2 (0.001 — With Heat Treatment)

Nedox SF-2 − 0.001 (Gen Magnaplate Corp.)

Nedox CR + 0.001 (Gen Magnaplate Corp.) DK4036_book.fm Page 9 Monday, April 25, 2005 12:18 PM

Định dạng
Số trang	16
Dung lượng	1,14 MB