Colour of gas-pressure-sintered silicon nitride ceramics - Part I. Experimental data

Gas-pressure sintering is the most widely used process for manufacturing hi gh-performance silicon nitride ceramics. The interaction between the sinter ing atmosphere and the silicon nitride ceramics is often featured by an inh omogeneous grey coloration of the near surface area and a grey coloration o f the bulk material. In Part I of this work the dependence of the colour of the material on the sintering parameters was investigated experimentally. It was shown that silicon inclusions having sizes ranging from a few nm up to several mum cause the coloration of the material. Gas pressure, temperat ure and sintering time influence the formation of the inhomogeneous grey co loration. (C) 2001 Elsevier Science Ltd. Ail rights reserved.