Silicon Nitride And Silicon Carbide Compared

Two hard ceramics that look interchangeable on a datasheet and are not. Where Si3N4 blades belong and where SiC rings belong.

Silicon nitride and silicon carbide are both specified when alumina wears through too quickly. They share a temperature rating of 1200C and a reputation for hardness, but they are bought for different reasons.

Silicon Nitride Si3N4

Described on our own product pages as having the best comprehensive performance in structural ceramics.
High strength, high hardness, wear resistance and corrosion resistance, with good thermal shock resistance so it is not afraid of rapid temperature changes.
Good heat dissipation, good insulation performance and low density.
Good biocompatibility and high density.
Supplied black, in customised dimensions, MOQ 10 pieces.

Silicon Carbide SiC And SSiC

The same headline properties, bought for abrasive and corrosive duty rather than for impact.
Held to plus or minus 0.005mm on rings and cylinders, which is the tightest tolerance we publish.
Good chemical stability that resists acid corrosion at high temperatures.
Low thermal conductivity with high corrosion resistance.

Choosing Between Them

A blade, a knife edge or anything that takes a shock load leans to Si3N4.
A seal ring, a cylinder or a wear sleeve running in slurry leans to SiC.
Where the part is both, send the drawing and the duty and we will quote both.

Every figure quoted above is taken from the property tables published on our own product pages. If your drawing needs a value we do not publish, ask and we will confirm it against the grade we would supply.