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

Gas-pressure sintering is the most widely used process for manufacturing high-performance silicon nitride ceramics. The interaction between the sintering atmosphere and the silicon nitride ceramics is often featured by an inhomogeneous grey coloration of the near surface area and a grey coloration of 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 μm cause the coloration of the material. Gas pressure, temperature and sintering time influence the formation of the inhomogeneous grey coloration.