原位反应锆英石结合的多孔SiC陶瓷的制备

Fabrication of Porous SiC Ceramics Bonded by in-situ Formed Zirconite

以α-SiC粉和c-ZrO2粉为原料,聚乙烯醇缩丁醛(polyvinyl butyral,PVB)为造孔剂,通过干压成型,在空气气氛中无压烧结制备了原位反应锆英石结合的多孔SiC陶瓷。研究了烧结温度对多孔SiC陶瓷的相组成、线膨胀、开口气孔率、孔径分布及压缩强度的影响,并对多孔SiC陶瓷的显微结构进行了分析。结果表明:PVB的分解和SiC颗粒间的堆积间隙产生气孔。SiC颗粒表面氧化生成的SiO2与ZrO2原位反应生成锆英石,SiC颗粒由锆英石和玻璃相结合。当烧结温度为1 500℃时,多孔SiC陶瓷的开口气孔率为50.3%,压缩强度达到38.7 MPa。

Zirconite-bonded porous SiC ceramics through in-situ reaction were fabricated by dry pressing molding and subsequent pressureless sintering process in air using α-SiC and c-ZrO2 as raw materials,and polyvinyl butyral（PVB） as pore-forming agent.The effects of sintering temperature on phase composition,linear expansion,open porosity,pore size distribution and compressive strength were investigated.In addition,the microstructure of the porous SiC ceramics was also analyzed.The results indicate that pores are produced by both the stacking of SiC particles and burning out of PVB.The surface of SiC particles is oxidized to SiO2 which then reacts with ZrO2 forming zirconite.SiC particles are bonded by zirconite and glass phase.At 1500 ℃,the compressive strength of porous SiC ceramics with open porosity of 50.3% reaches 38.7 MPa.