常压烧结ZrB2-SiC复相材料的抗氧化行为研究

Oxidation Behaviors of the Pressureless Sintered ZrB_2-SiC Composites

以溶胶-凝胶法合成的超细ZrB2粉体为主要原料,研究了不同含量Mo和Mo-B4C为烧结助剂时,ZrB2-SiC体系的常压烧结工艺,测试了其力学性能,并系统研究了分别以4wt%Mo和4wt%Mo-2wt%B4C为烧结助剂制备的ZrB2-20wt%SiC复相陶瓷在不同温度下的静态抗氧化行为,研究表明:仅以Mo作为烧结助剂时,在1300℃以上材料表面开始出现ZrO2颗粒析出而迅速氧化.当添加Mo-B4C复合烧结助剂时,液相保护层在1300℃开始出现,并随着温度升高逐步变厚且均匀,材料在1500℃氧化30min后,抗弯强度仍有室温强度的86%,表现出良好的抗氧化性能.

The pressureless sintering process of ZrB2-SIC composite ceramics was studied. The ceramic samples was prepared by using sol-gel synthesized ultra-fine ZrB2 powders as sources and different contents of Mo and/or B4C as sintering aids. The static oxidation behaviors of the sintered ZrB2-20wt% SiC composite ceramics using 4wt% Mo and 4wt% Mo-2wt% B4C additives were systemically analyzed. The results show that the composite ceramics oxidized quickly with visible ZrO2 particles on the surface above 1300℃/30min with pure Mo additive. While Mo-B4C additive is added, the protective liquid layer appears at 1300℃ and becomes thicker and uniform with the temperature rising. The composite ceramics present good oxidation resistance of which the flexural strength retains 86% of the value in room temperature after oxidiation at 1500℃ for 30min.