(湖南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410082)
摘 要: 以不同配比的粗、細(xì)SiC粉體和WC粉體為原料，在2 200 ℃以上燒結(jié)得到RSiC-WC復(fù)相陶瓷。采用XRD、SEM和EDS對(duì)復(fù)相陶瓷的物相組成和微觀形貌進(jìn)行分析，并測(cè)定其開口氣孔率、抗彎強(qiáng)度和電阻率。結(jié)果表明：RSiC-WC復(fù)相陶瓷中以6H-SiC和WC為主晶相，存在少量W2C晶相。燒結(jié)產(chǎn)物中SiC顆粒再結(jié)晶程度良好，WC在燒結(jié)溫度下與SiC晶粒潤(rùn)濕性好。RSiC-WC復(fù)相陶瓷的最低開口氣孔率、最高抗彎強(qiáng)度和最低電阻率分別為19.2%、109 MPa和15 mΩ·cm。體系中SiC晶粒生長(zhǎng)遵循蒸發(fā)−凝聚的燒結(jié)機(jī)理，WC則以W-C液相在SiC晶粒界面處聚集，抑制了SiC晶粒的長(zhǎng)大。高溫下形成的W-C液相能明顯降低復(fù)相陶瓷的開口氣孔率，使燒結(jié)體致密化。因而，添加一定量的WC改善復(fù)相陶瓷的力學(xué)性能，并對(duì)其電學(xué)性能起到調(diào)節(jié)作用。
關(guān)鍵字: RSiC-WC復(fù)相陶瓷；再結(jié)晶；燒結(jié)機(jī)理；力學(xué)性能；電學(xué)性能
RSiC-WC composite ceramics
（College of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract: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.
Key words: RSiC-WC composite ceramics; recrystallization; sintering mechanism; mechanical property; electrical property
