New High Zirconia fused cast material for high quality glass without low temperature oxygen blistering

New High Zirconia fused cast material for high quality glass without low temperature oxygen blistering ICF Technical meeting, Sienna November 05th , 2007... New High Zirconia fused cast

New High Zirconia fused cast material for high quality glass without low temperature oxygen

blistering

ICF Technical meeting, Sienna November 05th , 2007

New High Zirconia fused cast material for high quality Glass without low temperature oxygen blistering

 Main interest of HZFC material in high quality glass

 How to prevent oxygen blistering

 Influence of crystal glass composition evolution

regarding AZS and HZFC materials

Topics of the presentation

Interest of HZFC in quality

Zirconia Glassy phase

High Zirconia Fused Cast Microstructure

Typical composition

Fused Cast AZS Microstructure

Typical composition

microprobe mapping

Corundum / Zirconia eutectic

Main interest of using HZFC material

Low level of glass contact defects

 low level of Crystallized or vitreous defect origin of defects in

10% Al203, 2% ZrO2, 11% PbO, 16%K2O, 0.8% Na2O

Clear Knot

Main interest of using HZFC material

Low level of glass contact defects

 low level of blistering at high temperature

Test condition : TV/PDP glass, Temperature :1450°C, Duration :70H

HZFC

AZS (41%

ZrO2)

Crucible test

Low temperature oxygen

low temperature oxygen blistering

phenomenon

High quality glass  extended use of HZFC materials

in the furnace final part (fining, feeder, …)

 To solve some corrosion problem (borosilicate, crystal glass … )

 To prevent Glass contact defect related to chemical composition of the glass (compare alpha/béta alumina product, or AZS product )

Oxygen blistering phenomenon

Wt % 58-69 4 – 5 5 – 7 5 - 10 1 – 8 5 – 7 0 – 2 1 – 7 2 – 4

Low temperature oxygen blistering phenomenon

Necessary conditions to obtain high oxygen blistering

Blistering crucible test at 1120°C , 30 hours , alkali test glass

Low temperature oxygen blistering consequences

upward drilling phenomenon

Oxygen blistering in the join ( low

temperature area )

glass

cold area

1250°C

Hypothesis of this

T emperature

Low temperature oxygen blistering mechanism :

High temperature dependence of this phenomenon related to zirconia crystallographic transformation

Electrical conductivity process change with temperature at the zirconia crystalographic transformation

Low temperature oxygen blistering mechanism :

Résistivité électrique = f(température)

1 10 100 1000 10000 100000

Arrhenius diagram : Log(sigma) = f(1/T) for zirconia

glass Na+, K+

Oxydation

2 O 2-  O 2 + 4

e-Oxygen Blistering mechanism Hypothesis

Electro chemical process that can take place because of:

 alkali available in the glass

 electronic conductivity in the refractory at T<1130°C

 oxygen outside of the crucible that could be reduced (or that could reoxydized impurities)

réduction Reaction

Refractory wall

How to prevent low temperature oxygen blistering

Quadratic zirconia Monoclic zirconia

Glass crystallization temperature

How to prevent low temperature oxygen blistering

Y2O3 addition that allow to :

phase

Microprobe mapping of Y2O3

Y2O3 necessary level is related to glass crystallization curve

Comparaison entre dévitrification et courbe dilatométrique

Y2O3 target = [ 0.8 – 1%]

(Higlh quality display panel glass )

Sensible shift of zirconia transformation temperature

with Y2O3 addition

temperature transformation during the annealing process of the block

Thermal expansion curve

Glassy phase modification with Y2O3 addition

Glassy phase properties measurements in the

SiO2-Al2O3-Na2O-Y2O3 system  simulation

 Thermal expansion

 Glass transition temperature, crystallization

 High température viscosity

To design the right level of SiO2, Na20 and Al2O3 for a given Y2O3 %

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

SiO2 = 4 – 6 %, Al2O3 = 0.7 -1.2 %, Na2O = 0.4- 0.8%, Y2O3 = 0.8 – 1%

New HZFC materials : First industrial results

Cut block

Low level of internal defect

HZFC

Display panel glass High alkalii test glass

Blistering test results on industrial products :

No oxygen bubles with the new product at 1100°C

New HZYFC

High alkalii test glass

Crucible test : 1100°C , 30 hours

Display panel glass

HZFC

 No oxygen blistering up to 1000°C with new HZFC

 Secure solution with display panel glass (no blistering up to crystallization temperature)

High alkalii test glass

High alkalii test glass

New HZYFC

Blistering test results on industrial products :

Crucible test : 1000°C , 30 hours

Display panel glass

Display panel glass

Glass contact properties

5

Static corrosion test (T-test)

HZFC New HZFC stone

(droplet )

1-2 1-2 1-2 1-2

Stone (crucible)

Indice

Temperature : 1500°C Duration : 48 heures Glass : PDP

Conditions of the test :

Dynamic corrosion test (test MGR)

Température : 1500°C Duration : 48 heures Glass : PDP

Conditions d’essais :

Influence of crystal glass

composition evolution regarding

Crystal glass composition evolution

Second family: lead free glass without BaO, with main addition of ZnO, TiO2

 Evolution to lead free Glass

SAMSUNG CORNING 04/98

Glass evolution impact of refractory corrosion

Corroded Volume (cm3)

(cm3)

Index

 Corrosion level increase with lead free crystal glass

 Corrosion level with Crystal lead free glass with/without BaO are similar

 Lower corrosion resistance of HZFC compared to AZS material (protective interface

layer) in condition of high glass interface removal : this is not the case with horizontal interface like in paving or electrode block due to heavy enriched zirconia interface

Tests conditions

Temperature: 1450°C Time: 48 hours

Index given from 1 to 5 (1: no stone in drop, 5: lot of crystals in drop)

Glass evolution impact of refractory stoning potential

Lead crystals Index

Lead Crystal glass

HZFC – glass interface

200µ m

200µ m

No formation of HZFC/Crystal glass interface in each case

200µ m

Lead free Crystal glass

Lead Crystal

glass

AZS – glass interface

-Dissolution of alumina from eutectic crystals

-Free zirconia crystals

100µ m

200µ m

200µ m

200µ m

100µ m

200µ m

Lead free crystal glass

As a conclusion

 New HZFC solution to avoid low temperature oxygen blistering by modifying ZrO2 electrical properties

Less glass defects at low temperature (oxygen blisters)

 Better corrosion resistance without upward drilling phenomenon

in join (low temperature area )

Better filling of the block

 Same advantage as conventional HZFC product

 Enhance corrosion level

 Doesn’t affect the advantage of using HZFC in terms of

defect due to very sharp glass refractory interface