FINITE ELEMENT ANALYSIS OF SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS (SHS) OF SILICON NITRIDE

摘要

Self-propagating High-temperature Synthesis (SHS) is a cost effective process to synthesize advanced ceramic materials. In this work, the effect of reactant stoichiometry on the adiabatic temperature of the SHS of silicon nitride is studied and a 3-D time-dependent mathematical model based on the finite element analysis is developed to study the effects of the dimensions of the reaction system and ignition condition on the SHS process, including temperature and composition distributions as well as the production rate and conversion. Momentum transfer, heat transfer, reaction kinetics and temperature dependent thermodynamic properties are integrated in this model. The effects of pellet diameter, ignition time, ignition flux, green density of the reactant pellet, and composition of silicon nitride diluent on the initiation of the self-sustained reaction, temperature history and velocity of the reaction front movement are calculated using this model. The results of this work can be used to improve commercial production of nitride materials.