短纤维增强C-SiC复合材料的制备和性能

Preparation and properties of short-fiber-reinforced C/SiC composites

将T700或Nicalon-SiC短纤维、碳粉、硅粉和少量碳化硅粉混合,在1900℃热压烧结制备短纤维增强C-SiC复合材料,并对其组织、结构及性能进行了研究。结果表明:SiCf／C-SiC的相对密度和室温强度分别为95.3％和24.38MPa,均高于Cf／C-SiC的相对密度和室温强度,热压烧结过程中Cf的损伤严重。短纤雄增强C-SiC复合材料中,由于C相和SiC相的同时存在,在同一温度下的氧化行为表现为在氧化初期氧化质量损失率较大,C相的氧化起主要作用;随氧化时间的增长,氧化质量损失率逐渐减小;在氧化后期则质量增加,SiC相的惰性氧化起主要作用。SiCf／C-SiC复合材料的抗氧化性能优于Cf／C-SiC复合材料的抗氧化性能。SiCf／C-SiC复合材料在温度为1100℃～1400℃时,温度越高,氧化质量损失率越小,抗氧化性能越强。

Short-fiber-reinforced C/SiC composites were fabricated by mixing the raw materials of T700 or Nicalon-SiC short fiber, carbon powder, silicon powder,silicon carbide powder and then hot-pressing sintered at 1 900 ℃. The properties of short-fiber-reinforced C-SiC composites show that the density and room temperature bending strength of SiC-fiber-rein-forced composites(SiCf/C-SiC)are higher than those of C-fiber-reinforced composites (Cf/C-SiC). Carbon fiber is damaged seriously during the hot-pressing sintered process. The mass of the composites specimens decreases quickly at the initial stage of oxidation because of the oxidization of C phase, and increases slightly instead after being oxidized some time due to the passive oxidization of SiC phase when composites are oxidized at 1 300 ℃. The oxidation resistance of SiCf/C-SiC is better than that of Cf/C-SiC. The higher the oxidation temperature, the less the oxidation mass loss when the composites are oxidized in the temperature range of 1000-1400 ℃.