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Syalon 21R Polytype is a silicon aluminium oxynitride structural modification of aluminium nitride (AlN), having the formulation (SiAl6O2N6). It is a refractory material which is predominately used in sialon formulations. It is used to increase the aluminium and nitrogen content of sialon formulations but has the advantage over AlN in that it is not readily hydrolysed by water. This allows sialon formulations containing 21R Polytype to be processed by aqueous slip casting or spray drying, for example.

The table below shows the typical composition and particle size for 21R Polytype, which is available in two grades, standard 21R and fine 21RF.

Typical property data for 21R Polytype and 21RF Polytype

Typical property data obtained under test conditions. The values given only apply to the test bodies on which they were determined, and therefore can only be recommended values. See our disclaimer.