The high porosity silicon nitride foams prepared by the direct foaming method

Silicon nitride foams with porosity higher than 90% were fabricated by direct foaming method. The influence of the surfactant content, solid content and rotating speed on the foamability and stability of wet foams were discussed and the corresponding effect on the total porosity, pore size distribution and mechanical property of ceramic foams were systematically investigated. The results showed that the pore structure and porosity, the compressive strength of Si3N4 ceramic foams could be controlled by tailoring surfactant and solid content. The results indicated that rotating speed had a great impact on the pore size distribution. Si3N4 ceramic foams with porosity of 90.8-96.4% and compressive strength of 0.37-5.53 MPa were obtained.