Abstract:

Using zircon,boric acid and carbon black as starting materials,ZrB₂-ZrO₂-SiC composite powder was synthesized by calcining at 1 500 ℃ in flowing argon atmosphere.The effects of the soaking time (3,6 and 9 h) and the addition of additive AlF₃ (0,0.5%,1.0%,1.5%,2.0% and 2.5%,by mass) on the phase composition and the microstructure of the synthesized products were investigated.The results show that:(1)ZrB₂-ZrO₂-SiC composite powder can be synthesized by carbothermal reduction at 1 500 ℃ in flowing argon atmosphere;ZrB₂ and ZrO₂ are granular-like,and SiC crystals are fiberous;(2)with the soaking time increasing,the amount of ZrB₂ increases,the amounts of m-ZrO₂ and SiC decrease,and the total amount of non-oxides ZrB₂,SiC and ZrC gradually increases;(3)compared with the specimen without AlF₃,the specimen with 0.5% AlF₃ has decreased m-ZrO₂ amount,noticeably increased ZrB₂ amount but decreased SiC amount;however,when the amount of AlF₃ increases from 0.5% to 2.5%,the m-ZrO₂ amount increases,the ZrB₂ amount decreases,and the SiC amount changes slightly;the optimum AlF₃ addition is 0.5%.

Key words: zircon, carbothermal reduction, zirconium diboride-zirconia-silicon carbide composite powder, microstructure

摘要：

以锆英石、硼酸和炭黑为原料,在流通氩气气氛中于1 500 ℃煅烧制备ZrB₂-ZrO₂-SiC复合粉体,研究了保温时间(分别为3、6和9 h)和添加剂AlF₃添加量(质量分数分别为0、0.5%、1.0%、1.5%、2.0%和 2.5%)对合成产物物相组成和显微结构的影响。结果表明:1)将锆英石在流通氩气气氛中于1 500 ℃碳热还原可制备ZrB₂-ZrO₂-SiC复合粉体;ZrB₂、ZrO₂呈粒状,SiC呈纤维状。2)随着保温时间的延长,ZrB₂的量逐渐增多,m-ZrO₂和SiC的量均逐渐减少,非氧化物ZrB₂、SiC、ZrC的总量逐渐增多。3)与未添加AlF₃的试样相比,添加0.5%(w)AlF₃的试样中m-ZrO₂量显著减少,ZrB₂的量显著增多,SiC的量有所减少;但随着AlF₃添加量从0.5%(w)增加到2.5%(w),m-ZrO₂的量逐渐增多,ZrB₂的量逐渐减少,SiC的量变化不大;AlF₃的适宜添加量应为0.5%(w)。

关键词: 锆英石, 碳热还原, ZrB₂-ZrO₂-SiC复合粉体, 显微结构