Formation of an alpha-SiAION layer on beta-SiAION and its effect on mechanical properties

Abstract

We have developed a technique for in situ formation of an alpha-SiAlON layer on sintered beta-SiAlON. The technique consists of packing a powder compact of beta-SiAlON composition with alpha-SiAlON composition powder, presintering, and sintering. Using this technique, it is possible to control the thickness of the layer by changing the presintering conditions during heating to a sintering temperature. The introduction of an alpha-SiAlON layer increases the surface hardness and improves the wear and oxidation resistance, with a moderate reduction of flexural strength. The surface modification of beta-SiAlON may provide opportunities of wider application of beta-SiAlON to wear- and oxidation-resistant components.