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Physical data		 Physical properties of Aluminia, Zirconia and Sapphire 
Materials Al2O3 ZrO2 Sapphire
Main Constituent 99.9% 98% 99.998%
Specific Gravity 3.97 g/cm3 6.07 g/cm3 3.98 g/cm3
Theoretical Density 99% >99% 99.998%
Open Porosity 0% 0% 0%
Average Grain Size 2-6 microns 0.5 microns 0 micron
Hardness Vickers 2000 HV 1300 HV 2500 HV
Hardness Mohs 9 8 9
Compressive Strength 380'000 N/cm2 210'000 N/cm2 180'000 N/cm2
Bending Strength 40'000 N/cm2 100'000 N/cm2 60'000 N/cm2
Modulus of Elasticity 3.8 x 105 N/mm2 2.0 x 105 N/mm2 3.5 x 105 N/mm2
Tensil Strength 300 N/mm2 1'000 N/mm2 200 N/mm2
 
Materials Al2O3 ZrO2 Sapphire
Fracture Toughness K 1c 4 MN/m3/2 8 MN/m3/2 6 MN/m3/2
Max. Operating Temperature 1'900°C 1'000°C 1'600°C
Coefficient of Thermal
Expansion 20 - 1000°		 8 (10-6 °C-1) 10 (10-6 °C-1) 7 (10-6 °C-1)
Thermal Conductivity
* (at 20°C)		 40 W/mK 2.5 W/mK *
0.08cal/sec cm°C
Specific Heat 900 J/Kg K 500 J/Kg K 700 J/Kg K
Electrical Resistivity
at 20 - 1000°C		 >1014 Ohm cm - >1011 Ohm cm
Dielectric Constant, 100 MHz 9.6 - 8.5 - 11
Dielectric Loss Factor 10-4 tg d - 10-4 tg d

Materials Al2O3 ZrO2 Sapphire
Infra-red Transmission 5 mm thk. at 10'000Å = 83%
Factor of Ultra-violet at 57'000Å = 30%
Transmission Factor 1 mm thk. at 1'450Å = 10%

 
 

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SJC Advanced Ceramics, Swiss Jewel CO. SA., Via del Sole, CH-6598 Tenero, Switzerland
Phone: +41-91-745 61 31     Fax: +41-91-745 61 69    e-mail: sales@swiss-jewel.com