Sintering and microstructure of silicon nitride with magnesia and cerium additives

This paper deals with the pressureless sintering and microstructure of Si3N 4-MgO-CeO2 ceramics. The sintered Si3N4-MgO-CeO2 ceramics achieved a relati ve density of 98.5% and a bending strength of 950 MPa. XRD, TEM and EDAX an alysis indicated that the main composition of the glassy phase in the sinte red Si3N4-MgO-CeO2 ceramics was cerium silicate and that it hardly containe d any MgO: during sintering, MgO would crystallize. Abnormal grain growth o ccurred at 1850 degreesC, which led to microcracks and dislocation. Some si licon whiskers were growing in fractal patterns during TEM observation, whi ch provided a good experimental example for further study of fractal growth . (C) 2001 Published by Elsevier Science B.V.