Finite Element Analysis of Self‐Propagating High‐Temperature Synthesis (SHS) of Silicon Nitride

This chapter examines the impact of reactant stoichiometry on the adiabatic temperature of the self-propagating high-temperature Synthesis (SHS) of silicon nitride. The chapter presents a 3-D time-dependent mathematical model based on the finite element analysis to examine the impact 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. The heat output from the ignitor was controlled by a variable auto-transformer. The heat source was turned off after one end of the pellet was ignited. Then the reaction propagated through the whole pellet like a wave from the ignition end. The steady state Navier-Stokes equation and the continuity equation are first used to solve the nitrogen flow profile inside the reactor before the SHS reaction. It suggests that the heat conducted to the outer surface of the pellet is equal to the radiation and convective heat losses from the pellet outer surface to the surrounding nitrogen gas.