Abstract: In order to explore the effect of BN micropowder addition on the high temperature oxidation resistance of Si₃N₄-BN composites,Si₃N₄-BN composites with different BN micropowder additions (0,12%,26%,and 41%,by mass) were prepared using Si powder,Si₃N₄ powder,and h-BN micropowder as main raw materials by reaction sintering technology.The oxidation test was carried out at 1 200 ℃ in a static air atmosphere for 2-20 h.The apparent porosity,the cold modulus of rupture,the cold compressive strength of the samples before and after oxidation were detected,and the samples were investigated by XRD and SEM.The results show that: when the BN micropowder addition is 41%,the oxidation resistance of the reaction sintered Si₃N₄-BN sample is the best,which is significantly better than that of the reaction sintered Si₃N₄ sample;the B containing glass phase formed in the oxidation product forms a dense protective layer on the sample surface,which is the key factor for the excellent oxidation resistance of the composites.

Key words: silicon nitride, boron nitride, silicon nitride-boron nitride composites, reaction sintering, oxidation resistance

摘要： 为探究BN微粉加入量对Si₃N₄-BN复合材料高温抗氧化性的影响,以Si粉、Si₃N₄粉、h-BN微粉为主要原料,采用反应烧结技术制备了BN微粉加入量(w)分别为0、12%、26%、41%的Si₃N₄-BN复合材料。在1 200 ℃、静态空气气氛下进行2~20 h的氧化试验,检测了试样氧化前后的显气孔率、常温抗折强度、常温耐压强度,并进行XRD和SEM分析。结果表明:当BN微粉加入量为41%(w)时,反应烧结Si₃N₄-BN试样的抗氧化性能最优,显著优于反应烧结Si₃N₄试样;氧化产物形成的含B玻璃相在试样表面形成的致密保护层是复合材料具有优良抗氧化性能的关键因素。

关键词: Si₃N₄, BN, Si₃N₄-BN复合材料, 反应烧结, 抗氧化性