Effect of Sintering Process on Properties of Si_3N_4 Foam Ceramics

In the process of preparing porous silicon nitride ceramic by impregnating a polyurethane sponge,the effect of heating rate,the amount of additives and sintering temperature on the microstructure of porous silicon nitride ceramic,phase and mechanical properties are discussed.Result of study indicates,with the content of Y2O3 and Al2O3 increasing,the strength of sintering body obviously increases.And the optimum amount of their content is 20%.By analyzing the DSC-TDA curve of polyurethane sponge,it can be show the temperature should be slowly warmed up from 150 ℃ to 475 ℃.The optimum sintering temperature is about 1700 ℃,and the phase transition is more complete.