氮化硅添加对定向梯度多孔碳化硅陶瓷制备的影响

he directional SiC porous ceramics by the high-temperature recrystallization process using silicon nitride as pore formation agent. And the effect of Si3N4 on directional microstructure and performance of porous silicon carbide ceramic was examined by XRD, SEM analysis. The results showed that the obtained silicon carbide ceramic had high porosity, continuous gradient distribution of pore size and pore density from the bottom to the top, indicated the characteristics of aligned holes by the adding Si3N4. With the Si3N4 content increased, the rate of weight loss increased, and the silicon carbide particles tend to become rounded, pore size also decreases, the connection between the particles became more strong. X-ray diffraction analysis showed the diffraction peak of the silicon nitride crystal of α-SiC (6H). With the Si3N4 content increases from 0% to 15%, total porosity increase from 38.7% to 45.1% with the increased silicon nitride content, and strength decreased from 38.2MPa to 33.1MPa.