New High Zirconia fused cast material for high
- Slides: 36
New High Zirconia fused cast material for high quality glass without low temperature oxygen blistering ICF Technical meeting, Sienna November 05 th , 2007
New High Zirconia fused cast material for high quality Glass without low temperature oxygen blistering Topics of the presentation Ø Main interest of HZFC material in high quality glass Ø Low temperature oxygen blistering phenomenon Ø Hypothesis of mechanism with HZFC Ø How to prevent oxygen blistering Ø Properties of new HZFC Ø Influence of crystal glass composition evolution regarding AZS and HZFC materials
Interest of HZFC in quality glass 1
High Zirconia Fused Cast Microstructure Typical composition Al 2 O 3: 0. 4 - 2 % Zr. O 2 > 90 % Si. O 2: 3 - 7 % Na 2 O: 0 – 0. 4 % B 2 O 3: 0 – 1 % Zirconia microprobe mapping Al 2 O 3 Si. O 2 Glassy phase Na 2 O 100 µm Zr. O 2
Fused Cast AZS Microstructure Typical composition Al 2 O 3: 46 % Zr. O 2: 41% Si. O 2: 12 % Na 2 O: 1% Zirconia microprobe mapping Al 2 O 3 Zr. O 2 Glassy phase Corundum / Zirconia eutectic Si. O 2 Na 2 O
Main interest of using HZFC material Low level of glass contact defects Ø low level of Crystallized or vitreous defect HZFC origin of defects in convective area as : AZS (41% Zr. O 2) 10% Al 203, 2% Zr. O 2, 11% Pb. O, 16%K 2 O, 0. 8% Na 2 O Leucite (Al 203 -K 2 O-4 Si. O 2) with zirconia nodule Glass contact AZS interface, primary Zr. O 2 Clear Knot
Main interest of using HZFC material Low level of glass contact defects Ø low level of blistering at high temperature Test condition : TV/PDP glass, Temperature : 1450°C, Duration : 70 H Crucible test HZFC AZS (41% Zr. O 2)
Low temperature oxygen blistering phenomenon 2
low temperature oxygen blistering phenomenon High quality glass extended use of HZFC materials in the furnace final part (fining, feeder, …) ü To solve some corrosion problem (borosilicate, crystal glass …. . ) ü To prevent Glass contact defect related to chemical composition of the glass (compare alpha/béta alumina product, or AZS product ) Glass Si. O 2 Na 2 O K 2 O Ca. O Wt % 58 -69 4– 5 5 - 10 1 – 8 5– 7 Ba 0 Sr. O Mg. O Al 2 O 3 5– 7 0– 2 Oxygen blistering phenomenon 1– 7 Zr. O 2 2– 4
Low temperature oxygen blistering phenomenon Ø Blistering phenomenon with high efficiency Blistering crucible test at 1120°C , 30 hours , alkali test glass Necessary conditions to obtain high oxygen blistering Ø Air outside crucible Ø Temperature < 1130°C Ø Alkalii inside the glass
Low temperature oxygen blistering consequences Electrical furnace HZ 1250°C • bubble defect in glass 1120°C cold area Glass glass • Corrosion enhancement by upward drilling phenomenon Oxygen blistering in the join ( low temperature area )
Hypothesis of this phenomenon 3
Low temperature oxygen blistering mechanism : Thermal expansion % High temperature dependence of this phenomenon related to zirconia crystallographic transformation Monoclinic zirconia Quadratic zirconia Temperature 1120 -1140°C
Low temperature oxygen blistering mechanism : Conductivity process change with zirconia transformation Electrical conductivity process change with temperature at the zirconia crystalographic transformation
Low temperature oxygen blistering mechanism : Arrhenius diagram : Log(sigma) = f(1/T) for zirconia contribution 1/T(K°) 0 0 1 E-04 2 E-04 3 E-04 4 E-04 5 E-04 6 E-04 7 E-04 8 E-04 9 E-04 0, 001 0, 001 0, 002 -2 Ln sigma (ohm-1. cm-1) -4 -6 -8 ER 1195 Activation energy increase after zirconia transformation -10 -12 -14 ØElectronic to ionic conductivity change at the zirconia temperature transformation
Oxygen Blistering mechanism Hypothesis Refractory wall Oxydation 2 O 2 - O 2 + 4 e- glass M Y+ + x e- M y-x Na+, K+ réduction Reaction e- Electro chemical process that can take place because of: Ø alkali available in the glass Ø electronic conductivity in the refractory at T<1130°C Ø oxygen outside of the crucible that could be reduced (or that could reoxydized impurities)
How to prevent low temperature oxygen blistering with HZFC 4
How to prevent low temperature blistering in glass D e fo r m a ti o n % Y 2 O 3 addition Monoclic zirconia Quadratic zirconia Temperature Glass crystallization temperature
How to prevent low temperature oxygen blistering Y 2 O 3 addition that allow to : ü lower the electronic conductivity temperature area Ø Stay stable with temperature Ø Doesn’t react with alumina or silica inside the glassy phase Ø Form solid solution with zirconia Microprobe mapping of Y 2 O 3
Y 2 O 3 necessary level is related to glass crystallization curve (Higlh quality display panel glass ) Y 2 O 3 target = [ 0. 8 – 1%]
Sensible shift of zirconia transformation temperature with Y 2 O 3 addition Ø Need to adapt the glassy phase composition to the lower reverse temperature transformation during the annealing process of the block
Glassy phase modification with Y 2 O 3 addition Glassy phase properties measurements in the Si. O 2 -Al 2 O 3 -Na 2 O-Y 2 O 3 system simulation ü Thermal expansion ü Glass transition temperature, crystallization ü High température viscosity To design the right level of Si. O 2, Na 20 and Al 2 O 3 for a given Y 2 O 3 %
New HZFC materials : First industrial results Cut block Low level of internal defect Si. O 2 = 4 – 6 %, Al 2 O 3 = 0. 7 -1. 2 %, Na 2 O = 0. 4 - 0. 8%, Y 2 O 3 = 0. 8 – 1%
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
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 ü No oxygen blistering up to 1000°C with new HZFC ü Secure solution with display panel glass (no blistering up to crystallization temperature)
Glass contact properties 5
Static corrosion test (T-test) HZFC stone New HZFC 1 -2 1 -2 0 0 -1 1 1 (droplet ) Stone (crucible) Indice global Conditions of the test : Temperature : 1500°C Duration : 48 heures Glass : PDP
Dynamic corrosion test (test MGR) HZFC Indice 100 New HZFC 105 83 Conditions d’essais : Température : 1500°C Duration : 48 heures Glass : PDP 88
Influence of crystal glass composition evolution regarding AZS and HZFC materials 6
Crystal glass composition evolution Evolution to lead free Glass Typical Pb. O Crystal Glass Lead free Glass (Ba. O) Lead free Glass (w/o Ba. O) Na 2 O 3 -5 7, 5 -11 8, 6 -10, 9 K 2 O 10 -14 5 -7 8, 7 -10 5, 9 -8, 9 Ba. O Al 2 O 3 <0, 05 0, 4 -3, 4 1 -2 Zn. O 0 -2 0, 9 -2, 3 -5, 5 Pb. O 25 -32 Ca. O 2 -6 4 -6 Ti. O 2 <0, 05 1 -1, 7 Si. O 2 in complement First family : lead free glass with Ba. O addition, ( increase of Al 2 O 3, Ca. O, Na 2 O, decrease of K 2 O ) Second family: lead free glass without Ba. O, with main addition of Zn. O, Ti. O 2
Glass evolution impact of refractory corrosion Not working at iso viscosity Tests conditions : Diameter: 22 mm, height: 100 mm Speed: 6 rpm Temperature: 1450°C, duration 72 hours HZFC Corroded Volume (cm 3) Crystal Glass AZS (41% Zr. O 2) Index Corroded Volume (cm 3) Index 2, 62 53 1, 41 100 Lead free Glass (Ba. O), 3. 85 79 3. 09 100 Lead free Glass (W/o Ba. O) 4, 53 63 2, 88 100 Ø Corrosion level increase with lead free crystal glass Ø Corrosion level with Crystal lead free glass with/without Ba. O are similar Ø 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
Glass evolution impact of refractory stoning potential Tests conditions Temperature: 1450°C Time: 48 hours HZFC AZS Lead crystals HZFC AZS (41% Zr. O 2) HZFC Index 0 1 -2 Lead free (Ba. O) HZFC AZS (41% Zr. O 2) Index given from 1 to 5 (1: no stone in drop, 5: lot of crystals in drop) AZS Index 0 0 - 1
HZFC – glass interface Lead Crystal glass Lead free Crystal glass 200µ m No formation of HZFC/Crystal glass interface in each case
AZS – glass interface Lead Crystal glass Lead free crystal glass 100µ m 200µ m -Dissolution of alumina from eutectic crystals -Free zirconia crystals
Glass defect coming from AZS material in lead free crystal glass Chemical composition of glass defect % 1 2 3 4 Na 2 O 9. 9 10. 3 10. 4 K 2 O 3. 9 3. 8 4. 0 Mg. O 0. 05 0. 03 0. 04 0. 05 Al 2 O 3 13. 4 13. 6 13. 7 13. 6 Ca. O 5. 3 4. 9 Zn. O 0. 8 0. 7 Zr. O 2 6. 7 6. 6 6. 4 Ba. O 4. 9 5. 2 4. 8 4. 7 Ti. O 2 0. 03 0. 08 0. 03 0. 04 SO 3 - -
As a conclusion Ø Glass composition change towards lead free glass Ø Enhance corrosion level Ø Doesn’t affect the advantage of using HZFC in terms of defect due to very sharp glass refractory interface Ø New HZFC solution to avoid low temperature oxygen blistering by modifying Zr. O 2 electrical properties üLess glass defects at low temperature (oxygen blisters) ü Better corrosion resistance without upward drilling phenomenon in join (low temperature area ) üBetter filling of the block ü Same advantage as conventional HZFC product
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