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

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