A hard, chemically inert oxide that is often used as a mechanical seal face material.
The newer ceramics include products referred to as silicon carbide. Many ceramics are poor conductors of heat but the silicon carbides do not have his problem.
The common ceramics we find in the sealing industry include:
- 85.0 Meaning 85% aluminum oxide with the balance mainly silica.
- 99.5. Meaning 99.5% aluminum oxide with no silica. A small amount of cesium is added to control the grain size and improve the firing characteristics.
- Reaction bonded. Also called silicon carbide. It contains 15% to 18% silica that can be attacked by high pH fluids.
- Alpha sintered. Also called silicon carbide, but contains no silica.