热压烧结工艺制备C/SiC复合材料的抗烧蚀性能

Ablation Resistance of C/SiC Composites Prepared by Hot-pressed Sintering Process

以SiC粉、碳纤维和酚醛树脂为主要原料,采用热压工艺制备了C/SiC复合材料。采用正交试验法研究了碳纤维含量、烧结温度和烧结压力对C/SiC复合材料抗烧蚀性能的影响。采用X射线衍射仪、电子扫描显微镜及氧-乙炔烧蚀法对样品物相组成、显微结构及抗烧蚀性能进行表征。结果表明:烧结温度对C/SiC复合材料的抗烧蚀性能影响最大,其次为碳纤维含量。烧结温度与热压压力的提高有助于样品的致密化烧结,但过高的烧结温度与热压压力会促进Si元素向碳纤维扩散,对抗烧蚀性能不利。过多碳纤维的引入不利于样品致密化,会导致抗烧蚀性能降低。当烧结温度为2050℃,热压压力为20 MPa、碳纤维含量为25%(体积分数)时,C/SiC复合材料抗烧蚀性能最好,质量烧蚀率为2.0 mg/s。

C/SiC composites were prepared by the hot-pressed sintering process with SiC powder,carbon fiber and phenolic resin as raw materials.The effects of sintering pressure,sintering temperature and carbon fiber content on the ablation resistance of C/Si C composites were investigated via a designed orthogonal experiment.The phase composition,microstructure and ablation resistance of the samples were characterized by X-ray diffraction,scanning electron microscopy and oxygen-acetylene ablative method.The results show that the dominant factor affecting the ablation resistance of C/SiC composites is sintering temperature,while the minor factor is carbon fiber content.Increasing the sintering temperature and hot pressing pressure can be beneficial to the densification of the sample.However,the excessive sintering temperature and sintering pressure can promote the diffusion of Si element into carbon fiber that does not favor the ablative performance.In addition,the introduction of excessive carbon fiber is not conductive to the densification of the sample,thus leading to the ablation resistance reduction.With the sintering temperature of 2 050 ℃,the hot pressing pressure of 20 MPa and the volume fraction of carbon fiber of 25%,the obtained samples exhibit the superior ablation resistance with a mass ablation rate of 2.0 mg/s.