煤泥对定向多孔SiC陶瓷定向孔形成机制和性能影响研究

Research on the Effect of Coal Slime on the Formation Mechanism and Properties of Directional Porous SiC Ceramics

通过添加煤泥制备了定向多孔SiC陶瓷,探讨了煤泥加入后定向孔形成机制和烧结制度对制品性能影响.结果显示:煤泥内部碳热还原反应生成的SiC颗粒促进管状气孔、柱状组织的形成,未参与碳热还原反应多孔碳有效吸纳了混合气体中硅蒸汽,抑制了梯度多孔的形成,TiO2成份与多孔碳高温反应生成TiC增强相,氧化铝熔体与SiC和残余碳反应导致柱状组织表面圆润,也有效消耗了残余多孔碳.烧结温度的提升和保温时间的延长都有效促进了物质传输,促进了气孔率、烧失率、气孔尺寸的进一步增加,煤泥的加入为重结晶提供了大量SiC源和碳源,进一步抑制了重结晶SiC颗粒的挥发.

In this paper,directional porous SiC ceramics were prepared by adding coal slime.The formation mechanism of oriented pores and the effect of sintering system on the properties of the products were discussed.The results show that the SiC particles generated by the carbothermal reduction reaction inside the coal slime promote the formation of tubular pores and columnar structures.Porous carbon that does not participate in the arbothermal reduction reaction effectively absorbs silicon vapor in the mixed gas and inhibits the formation of gradient pores.TiO2components react with porous carbon at high temperature to generate TiC reinforcement phase.The reaction of aluminum oxide melt with SiC and residual carbon results in the formation of columnar structures with rounded surfaces,which also effectively consumes residual porous carbon.The increase of sintering temperature and the extension of holding time effectively promote the material transfer,and further increase the porosity,loss on ignition and pore size.The addition of coal slime provides a large number of SiC and carbon sources for recrystallization,which further inhibits the volatilization of recrystallized SiC particles.