Siaun Ceramics: Retrospect and Prospect

Abstract

ABSTRACTThe future for sialon ceramics is bright. Engine components are slowly increasing in numbers and variety, and applications for wear parts and molten metal handling are set to flourish.Two major developments have been: (i) the production of useful sialon composites; and (ii) the ability to join pieces to make large and complex components.In (i), properties of a′:8′ sialon composites can be varied by processing modifications in ways that are impossible for single-phase materials. Also, densifying additives such as yttria and rare-earth oxides can subsequently be incorporated into the α′-structure to minimize the amount of intergranular glass. The potentialities of other composites including O′:B′, O′:ZrO2, B′:TiN and B′:BN are assessed.In (ii), the joining of sialons follows from an understanding of phase relationships, glass formation and glass-ceramics in the Y-Si-Al-O-N system. Its exploitation has greatly widened the field of sialon applications.