Sialon

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Sialon ceramics are a specialist class of high temperature refractory materials, with high strength (including at temperature), good thermal shock resistance and exceptional resistance to wetting or corrosion by molten non-ferrous metals, compared to other refractory materials such as, for example, alumina. A typical use is with handling of molten aluminium. They also are exceptionally corrosion resistant and hence are also used in the chemical industry. Sialons also have high wear resistance, low thermal expansion and good oxidation resistance up to above ~1000°C.

Sialon stands for Silicon Aluminium Oxynitride. These materials are manufactured by high temperature reaction of silicon nitride with aluminium oxide (imparting greater oxidation resistance). Varying the constituents can vary the properties of the final ceramic. However, prolonged exposure to high temperatures can result in a sialon degrading back to these constituent parts.

Typical uses include metal feed tubes for aluminum die casting, burner and immersion heater tubes, injector and degassing for nonferrous metals, thermocouple protection tubes for nonferrous metal melting and brazing and welding fixtures and pins. The actual final shape of the parts can be achieved by hot isostatic pressing (and sintering in the process) or slip casting followed by pressureless sintering (providing greater shape and manufacturing flexibility).