Effect of foaming pressure on the properties of porous Si3N4 ceramic fabricated by a technique combining foaming and pressureless sintering

 To fabricate porous Si3N4 ceramics with a complex shape easily, a simple and low-cost technique combining foaming and pressureless-sintering is explored. The foaming pressure has a decisive effect on the microstructure, pore size distribution, porosity and mechanical properties of the porous Si3N4 ceramics. As the foaming pressure increases, the porous Si3N4 ceramics become uniform in microstructure, change gradually in pore size distribution from bimodal to unimodal, slowly reduce in porosity and pore size, and improve significantly in mechanical properties.