Effects of N2 pressure and Si particle size on mechanical properties of porous Si3N4 ceramics prepared via SHS

Abstract

Porous silicon nitride ceramics with high flexural strength and high porosity were directly fabricated by self-propagating high temperature synthesis (SHS). The effects of N2 pressure and Si particle size on the phase composition, microstructure, and mechanical property were investigated. N2 influences not only the thermodynamics but also the kinetics of the SHS as initial reactant. Flexural strength ranged between 67 MPa and 134 MPa with increasing N2 pressure. On the other hand, flexural strength ranged from 213 MPa to 102 MPa with different Si particle sizes. This plays an important role on the final diameter and length of β-Si3N4 grains and the formation mechanism of porous Si3N4 ceramics.