溶胶-凝胶法制备锆先驱体改性C/C复合材料

采用溶胶-凝胶法合成了锆先驱体，进一步制备了ZrC改性C/C复合材料，研究了锆凝胶在热处理过程中结构的变化。结果表明，锆凝胶在N₂条件下的热分解过程主要为结合水的脱除和羧酸盐的分解；900℃下锆凝胶的失重率为43.88%，灰分组成为ZrO₂和C。C/C-ZrO₂复合材料经1600℃处理得到C/C-ZrC，ZrC颗粒在材料中分散均匀且呈梯度分布，平均粒径约为28nm，锆元素质量分数（以ZrO₂计）约为10%；C/C-ZrC复合材料经1000℃氧化，表面出现能够阻止氧扩散的白色ZrO₂氧化膜；C/C-ZrC复合材料的氧化速率比C/C复合材料降低了40.03%，起始氧化温度比C/C复合材料提高了约300℃，材料的抗氧化性能得到明显的改善。

C/C composites modified by a sol gel based zirconium precursor

A zirconium precursor made by a sol-gel method has been used to prepare C/C-ZrC composites. A zirconium-containing gel was prepared and its structural evolution was studied during heat treatment. Pyrolysis of the gel in nitrogen resulted in a two-stage decomposition-removal of bound water followed by decomposition of carboxylate. The weight loss of the zirconium containing gel was 43.88% at 900℃, with the formation of ZrO₂ and C. Treated at 1600℃, the C/C-ZrO₂ composites transformed into C/C-ZrC. The particles of ZrC, which had an average particle size of 28nm, were scattered uniformly with a Zr (ZrO₂) mass fraction of 10%. Oxidation tests showed that a white ZrO₂ film preventing the diffusion of oxygen was formed on the surface of the C/C-ZrC composites. Compared with C/C composites, the oxidation protection of the C/C-ZrC composites, which have a 40.03% lower oxidation rate and an initial oxidation temperature about 300℃ higher than the corresponding values for C/C composites, was improved significantly.