Influence of the experimental conditions and the grinding of the starting materials on the structure of silicon nitride synthesised by carbothermal reduction

Silicon nitride has been obtained by carbothermal nitridation of silica usi ng Constant Rate Thermal Analysis (CRTA) method. This method permits to mai ntain the CO concentration generated in the reaction in a constant value pr eviously selected by the user. The results obtained have shown that the syn thesis of alpha -Si3N4 is improved by increasing the partial pressure of CO in the vicinity of the sample. The previous grinding of the mixture of car bon/silica to be used as raw material in the synthesis of silicon nitride l eads to an important reduction of the temperature, at which the carbotherma l reduction occurs at the time that an important modification of the partic le morphology takes place. (C) 2001 Elsevier Science B.V. All rights reserv ed.