原位莫来石结合碳化硅支撑体的高温力学性能研究

为研制可长期使用于800℃以上高温烟气净化的陶瓷膜过滤材料,采用原位反应结合技术制备了显气孔率为37. 2%、平均孔径为46. 5μm、常温抗折强度为22. 5 MPa的莫来石结合碳化硅支撑体,研究了其高温力学性能。结果表明:碳化硅支撑体的热态抗折强度随温度的升高呈现先升高后降低的变化趋势,在1 000℃时达到最大值36. 5 MPa,为常温抗折强度的1. 6倍;但在1 200℃时仍保持具有10 MPa以上的热态强度。SEM断口形貌显示,当温度由室温升至1 000℃再升至1 200℃时,支撑体断裂方式由沿晶-穿晶混合型断裂变为穿晶断裂再变为沿晶断裂。莫来石的耐高温性及其高温自增强特性赋予了碳化硅支撑体优异的高温力学性能,使其可满足800℃以上高温烟气过滤的使用要求。

Hot mechanical properties of in-situ mullite-bonded silicon carbide supports

In order to develop ceramic membrane filtration materials for long-term hot flue gas cleaning at above 800℃,mullite-bonded silicon carbide membrane supports with the apparent porosity of 37.2%,the average pore size of 46.5μm and the cold flexural strength of 22.5 MPa were prepared by an in-situ reaction bonding technique.The hot mechanical properties of the as-prepared supports were investigated.The results show that the hot modulus of rupture of the supports increases firstly and then decreases with the increase of the temperature,reaching the maximum of 36.5 MPa at 1000℃,which is 1.6 times of the cold modulus of rupture;however,the hot modulus of rupture of the supports is still higher than 10 MPa at 1200℃;the SEM fracture morphology shows that the fracture modes of the supports change from an intergranular and transgranular mixed mode fracture to the transgranular fracture,followed by the intergranular fracture when the temperature rises from the room temperature to 1000℃,and further to 1200℃.The high refractoriness and self-strengthening characteristics of mullite endow the supports with excellent hot mechanical properties,which can meet the requirements of hot flue gas filtration above 800℃.