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

2. Topics of the presentation
New High Zirconia fused cast material for high quality Glass without low temperature oxygen blistering
Topics of the presentation
Main interest of HZFC material in high quality glass
Low temperature oxygen blistering phenomenon
Hypothesis of mechanism with HZFC
How to prevent oxygen blistering
Properties of new HZFC
Influence of crystal glass composition evolution regarding AZS and HZFC materials

3. Interest of HZFC in quality glass1
Interest of HZFC in quality glass

4. High Zirconia Fused Cast Microstructure
Typical composition
microprobe mapping
Al2O3: %
ZrO2 > 90 %
SiO2: %
Na2O: 0 – 0.4 %
B2O3: 0 – 1 %
Al2O3
SiO2
ZrO2
Zirconia
Glassy phase
Na2O
100 µm

5. Fused Cast AZS Microstructure
Typical composition
microprobe mapping
Al2O3: 46 %
ZrO2: 41%
SiO2: 12 %
Na2O: 1%
Al2O3
ZrO2
Zirconia
Glassy phase
Corundum / Zirconia eutectic
Na2O
SiO2

6. Main interest of using HZFC material
Low level of glass contact defects
low level of Crystallized or vitreous defect
origin of defects in convective area as :
Clear Knot
HZFC
AZS (41% ZrO2)
Leucite (Al203-K2O-4SiO2) with zirconia nodule
10% Al203, 2% ZrO2, 11% PbO, 16%K2O, 0.8% Na2O
Glass contact AZS interface, primary ZrO2

7. 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
Crucible test
AZS (41% ZrO2)
HZFC

8. Low temperature oxygen blistering phenomenon2
Low temperature oxygen blistering phenomenon

9. 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 )
Glass
SiO2
Na2O
K2O
CaO
Ba0
SrO
MgO
Al2O3
ZrO2
Wt %
58-69
4 – 5
5 – 7
5 - 10
1 – 8
0 – 2
1 – 7
2 – 4
Oxygen blistering phenomenon

10. Low temperature oxygen blistering phenomenon
Blistering phenomenon with high efficiency
Blistering crucible test at 1120°C , 30 hours , alkali test glass
Necessary conditions to obtain high oxygen blistering
Air outside crucible
Temperature < 1130°C
Alkalii inside the glass

11. Low temperature oxygen blistering consequencesHZ
Electrical furnace
1250°C
bubble defect in glass
Corrosion enhancement by upward drilling phenomenon
Glass
cold area
glass
Oxygen blistering in the join ( low temperature area )

12. Hypothesis of this phenomenon3
Hypothesis of this phenomenon

13. Low temperature oxygen blistering mechanism :
High temperature dependence of this phenomenon related to zirconia crystallographic transformation
Monoclinic zirconia
Quadratic zirconia
Thermal expansion %
Temperature °C

14. Low temperature oxygen blistering mechanism :
Conductivity process change with zirconia transformation
Electrical conductivity process change with temperature at the zirconia crystalographic transformation

15. Activation energy increase after zirconia transformation
Low temperature oxygen blistering mechanism :
-14
-12
-10 -8 -6 -4 -2
1E-04
2E-04
3E-04
4E-04
5E-04
6E-04
7E-04
8E-04
9E-04
0,001
0,002
1/T(K°)
Ln sigma (ohm-1.cm-1)
ER 1195
Activation energy increase after zirconia transformation
Arrhenius diagram : Log(sigma) = f(1/T) for zirconia contribution
Electronic to ionic conductivity change at the zirconia temperature transformation

16. Oxygen Blistering mechanism Hypothesis
Refractory wall
réduction
Reaction
M Y+ + x e-  M y-x
glass
Oxydation
2 O2-  O2 + 4 e- e-
Na+, K+
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)

17. How to prevent low temperature oxygen blistering with HZFC4
How to prevent low temperature oxygen blistering with HZFC

18. How to prevent low temperature blistering in glass
Deformation %
Y2O3 addition
Monoclic zirconia
Quadratic zirconia
Temperature
Glass crystallization temperature

19. How to prevent low temperature oxygen blistering
Y2O3 addition that allow to :
lower the electronic conductivity temperature area
Stay stable with temperature
Doesn’t react with alumina or silica inside the glassy phase
Form solid solution with zirconia
Microprobe mapping of Y2O3

20. (Higlh quality display panel glass )
Y2O3 necessary level is related to glass crystallization curve
(Higlh quality display panel glass )
Y2O3 target = [ 0.8 – 1%]

21. Sensible shift of zirconia transformation temperature with Y2O3 addition
Need to adapt the glassy phase composition to the lower reverse temperature transformation during the annealing process of the block

22. 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 %

23. New HZFC materials : First industrial results
Cut block
Low level of internal defect
SiO2 = 4 – 6 %, Al2O3 = %, Na2O = %, Y2O3 = 0.8 – 1%

24. High alkalii test glass High alkalii test glass
Blistering test results on industrial products :
Crucible test : 1100°C , 30 hours
HZFC
Display panel glass
High alkalii test glass
New HZYFC
Display panel glass
High alkalii test glass
No oxygen bubles with the new product at 1100°C

25. High alkalii test glass High alkalii test glass
Blistering test results on industrial products :
Crucible test : 1000°C , 30 hours
HZFC
Display panel glass
High alkalii test glass
New HZYFC
Display panel glass
High alkalii test glass
No oxygen blistering up to 1000°C with new HZFC
Secure solution with display panel glass (no blistering up to crystallization temperature)

26. Glass contact properties5
Glass contact properties

27. Static corrosion test (T-test)
HZFC
New HZFC
stone
(droplet )
1-2
Stone
(crucible)
0-1
Indice global 1
Conditions of the test :
Temperature : 1500°C
Duration : 48 heures
Glass : PDP

28. Dynamic corrosion test (test MGR)
HZFC
New HZFC
Indice
100
105 83 88
Conditions d’essais :
Température : 1500°C
Duration : 48 heures
Glass : PDP

29. 6
Influence of crystal glass composition evolution regarding AZS and HZFC materials

30. Crystal glass composition evolution
 Evolution to lead free Glass
Typical PbO
Crystal Glass
Lead free Glass
(BaO)
(w/o BaO)
Na2O
3-5
7,5-11
8,6-10,9
K2O
10-14
5-7
8,7-10
BaO
5,9-8,9
Al2O3
<0,05
0,4-3,4
1-2
ZnO
0-2
0,9-2,3
2,3-5,5
PbO
25-32
CaO
2-6
4-6
TiO2
1-1,7
SiO2 in complement
First family : lead free glass with BaO addition, ( increase of Al2O3, CaO, Na2O, decrease of K2O )
Second family: lead free glass without BaO, with main addition of ZnO, TiO2

31. Glass evolution impact of refractory corrosion
Not working at iso viscosity
HZFC
AZS (41% ZrO2)
Corroded
Volume (cm3)
Index
Crystal Glass
2,62  53
1,41 
100
Lead free Glass (BaO),
3.85
79 
3.09  
100 
Lead free Glass (W/o BaO)
4,53 63
2,88
Tests conditions :
Diameter: 22 mm, height: 100mm
Speed: 6 rpm
Temperature: 1450°C,
duration 72 hours
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
SAMSUNG CORNING 04/98

32. Glass evolution impact of refractory stoning potential
Tests conditions
Temperature: 1450°C
Time: 48 hours
HZFC
AZS
HZFC
AZS
Lead crystals
Index
HZFC
AZS (41% ZrO2)
1-2
Lead free (BaO)
Index
HZFC
AZS (41% ZrO2)
0- 1
Index given from 1 to 5 (1: no stone in drop, 5: lot of crystals in drop)

33. Lead free Crystal glass
HZFC – glass interface
Lead Crystal glass
Lead free Crystal glass
200µm
200µm
No formation of HZFC/Crystal glass interface in each case

34. Lead free crystal glass
AZS – glass interface
200µm
Lead Crystal glass
100µm
200µm
Lead free crystal glass
100µm
200µm
-Dissolution of alumina from eutectic crystals
-Free zirconia crystals

35. Glass defect coming from AZS material in lead free crystal glass
Chemical composition of glass defect % 1 2 3 4
Na2O
9.9
10.3
10.4
K2O
3.9
3.8
4.0
MgO
0.05
0.03
0.04
Al2O3
13.4
13.6
13.7
CaO
5.3
4.9
ZnO
0.8
0.7
ZrO2
6.7
6.6
6.4
BaO
5.2
4.8
4.7
TiO2
0.08
SO3  - -

36. As a conclusion Glass composition change towards lead free glass
Enhance corrosion level
Doesn’t affect the advantage of using HZFC in terms of defect due to very sharp glass refractory interface
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