Comparative study of combustion laws for Mo-Si-N and W-Si-N ternary systems

Combustion laws in the Mo-Si-N and W-Si-N systems were studied. Thermodynamic analyses performed for these systems have shown that within certain intervals of parameters (the Si/Me ratio, nitrogen pressure, etc.), two-phase products consisting of MoSi2(WSi2) and Si3N4 are formed. Main factors influencing the combustion parameters, as well as phase composition and microstructure of products for both the systems considered were established experimentally. The leading stages of the combustion process in Mo(W)-Si-N systems (nitriding of silicon and/or siliconizing of the metal) depending on experimental conditions were revealed. Optimum conditions for synthesizing MoSi2-Si3N4 particulate composite containing 10 wt.% of silicon nitride were determined.