Jan 6 2004
Sialon® is a solid solution of Silicon Nitride with Aluminium Oxide and Aluminium Nitride. It exhibits high strength at high temperatures, is hard, tough and wear resistant. It is chemically inert and thermal shock resistant. These properties all make Sialon® ideal for foundry use, including use as containers for molten metals.
Sialon® is non-wetting for most non-ferrous metals up to 1000 °C. It has found use as thermocouple sheaths and the high wear resistance lends itself to components such as extrusion tools drawing dies and plugs.
The surface finish of Sialon® after firing may be improved by diamond grinding.
Key Properties
The key properties of Sialon are tabulated below.
Table 1. Key properties
| Chemical Resistance |
| Acids - concentrated |
Good |
| Acids - dilute |
Good |
| Alkalis |
Fair |
| Electrical Properties |
| Volume resistivity ( Ohm.cm ) |
1012-1017 @ 25 °C |
| Mechanical Properties |
| Compressive strength ( MPa ) |
>3500 |
| Hardness - Vickers ( kgf.mm-2 ) |
1650-1800 |
| Tensile modulus ( GPa ) |
280-300 |
| Tensile strength ( MPa ) |
400-450 |
| Physical Properties |
| Apparent porosity ( % ) |
0.01 |
| Density ( g.cm-3 ) |
3.24 |
| Thermal Properties |
| Coefficient of thermal expansion ( x10-6 K-1 ) |
3.3-3.7 @ 20-1000 °C |
| Specific heat ( J.K-1.kg-1 ) |
620-710 @ 25 °C |
| Thermal conductivity ( W.m-1.K-1 ) |
20 @ 20 °C |
| Upper continuous use temperature (°C ) |
1000 |
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