Material Properties

Properties	Unit	Sapphire	Ruby	Alumina	Silicon Nitride HP	Silicon Nitride sintered	Silicon Carbide	Zirconia Y-TZP	Zirconia Mg-PSZ / Y-PSZ
Structure	.	mono	mono	poly	poly	poly	poly	poly	poly
Composition (wt %)	.	Al2O3	99% Al2O3	Al2O3	Si3N4	Si3N4	SiC	ZrO2	ZrO2
Purity	%	99.99	99.90	99.80	90	90	(-)	90-95	90-95
Density	g/cm3	3.99	3.90	3.8-3.9	3.0-3.2	3.1-3.2	3.1-3.2	6.05	5.8
Hardness HV	-	2300	2300	1900	1600	1550	2400-2800	1200	1550
Compression strength	MPa	2100	2100	2500	3000	3000	1200-2900	2000	2000
Bending strength	MPa	390	390	470	1000	600-800	300-600	700-1100	400-800
Fracture toughness K1c	MN/m3/2	1	1	4	6	6	4	10	8-10
Elasticity constant	GPa	430	430	380	320	320	310	200	200
Thermal expansion	10-6 x K-1	5.3	4.5	8.1	3.2	3.2	4.1	10.5	10.5
Thermal conductivity	W/m K	36	36	29	40	40	85	2.5	2.5
Heat capacity	J/kg -K	755	755	900	750	700	800	500	500
Max. use temp. in air	°C	1800-2000	1800-2000	1500-1800	1200-1500	1200-1500	1600	1000	800-900
Chemical resistance	(acids) (bases)	excellent good	excellent good	excellent good	excellent good	excellent good	good good	good good	good good