Hardness

SILICON CARBIDE	HIGH LOW	23.0	Hardness Mechanical strength Variable electrical resistivity Distinct properties that can be tailored
ALUMINA		15-17.2	General use Wear resistance Electrical insulator Dielectric strength Low dielectric loss
SILICON NITRIDE		13.9	High toughness Thermal shock resistant Tight tolerances
ZIRCONIA		12.0	Toughness Mechanical Strength High Heat Resistance Corrosion Resistance
ALUMINIUM NITRIDE		10.4	Thermally stable Electrical resistivity
CORDIERITE		7.2	Good thermal expansion Excellent thermal shock resistance
STEATITE		5.8	Good dielectric strength Low dielectric loss