RSiC-WC复相陶瓷的性能及烧结机理  

Properties and sintering mechanism of RSiC-WC composite ceramics

作　　者：李青[1] 肖汉宁[1] 高朋召[1] 胡继林[1] 郭文明[1] 汤杰雄[1] 

机构地区：[1]湖南大学材料科学与工程学院,长沙410082

出　　处：《中国有色金属学报》2011年第6期1359-1366,共8页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(50972042)

摘　　要：以不同配比的粗、细SiC粉体和WC粉体为原料,在2 200℃以上烧结得到RSiC-WC复相陶瓷。采用XRD、SEM和EDS对复相陶瓷的物相组成和微观形貌进行分析,并测定其开口气孔率、抗弯强度和电阻率。结果表明:RSiC-WC复相陶瓷中以6H-SiC和WC为主晶相,存在少量W2C晶相。烧结产物中SiC颗粒再结晶程度良好,WC在烧结温度下与SiC晶粒润湿性好。RSiC-WC复相陶瓷的最低开口气孔率、最高抗弯强度和最低电阻率分别为19.2%、109 MPa和15 m-.cm。体系中SiC晶粒生长遵循蒸发-凝聚的烧结机理,WC则以W-C液相在SiC晶粒界面处聚集,抑制了SiC晶粒的长大。高温下形成的W-C液相能明显降低复相陶瓷的开口气孔率,使烧结体致密化。因而,添加一定量的WC改善复相陶瓷的力学性能,并对其电学性能起到调节作用。RSiC-WC composite ceramics were prepared using the coarse and fine SiC powders and WC powder as raw materials,which were well mixed in diverse proportion and ultimately sintered above 2 200 ℃.The phase composition and microstructure of the RSiC-WC composites ceramics were investigated by XRD,SEM and EDS.The open porosity,flexural strength and electrical resistivity were all measured.The results show that in this ceramics,6H-SiC and WC are the main crystalline phase,and W2C forms in the sintering process.The SiC grains recrystallize well,and the WC grains exist between SiC grains and well wet with SiC grains.The lowest open porosity,the highest flexural strength and the lowest electrical resistivity of the RSiC-WC composite ceramics are 19.2%,109 MPa and 15 mΩ-cm,respectively.The growth of SiC grains follow the evaporation-agglomeration mechanism,and W-C aggregates among SiC grain boundary in the form of W-C liquid phase,resulting in the inhibition of SiC growth.The W-C liquid phase formed at elevated temperature can evidently decrease the open porosity of the composites and improve the densification.Consequently,a certain addition of WC powder efficiently promotes the mechanical and electrical properties of RSiC-WC composite ceramics.

关 键 词：RSiC-WC复相陶瓷 再结晶 烧结机理 力学性能 电学性能 

分 类 号：O611.6[理学—无机化学]