HfB2-HfC-SiC 改性 C/C 复合材料的超高温烧蚀性能研究

目的制备HfB_2-HfC-SiC复相陶瓷改性C/C复合材料,并探究该材料的超高温烧蚀性能。方法采用化学气相渗透结合前驱体浸渍热解工艺制备HfC-SiC复相陶瓷改性C/C复合材料(C/C-HfC-SiC)和HfB_2-HfC-SiC复相陶瓷改性C/C复合材料(C/C-HfB_2-HfC-SiC),采用大气等离子烧蚀实验研究材料的超高温烧蚀性能。结果C/C-HfC-SiC和C/C-HfB_2-HfC-SiC复合材料2200℃线烧蚀率分别为1.54×10~(-3),1.38×10~(-3)mm/s。结论复合材料具有独特的微结构特征,亚微米级的HfB_2和HfC基体均匀弥散分布在SiC基体中。复合材料表面原位生成的液相SiO_2和固相HfO_2复合氧化物膜,既可以抵抗高速气流的冲蚀,又可以抵抗氧化性气氛的向内扩散,是复合材料具有优异超高温抗烧蚀性能的主要原因。

Ablation Behaviors of HfB2-HfC-SiC Ceramic Modified C/C Composites at Ultra-high Temperature

Objective To fabricate HfB2-HfC-SiC ceramic modified C/C composites and investigate the ablation perfor-mance of the composites at ultra-high temperature.Methods Chemical vapor infiltration (CVI) combined with precursor im-pregnation & pyrolysis (PIP) method were used to fabricate HfC-SiC ceramic modified C/C composites(C/C-HfC-SiC) and HfB2-HfC-SiC ceramic modified C/C composites(C/C-HfB2-HfC-SiC). Atmospheric plasma torch was used to investigate the ablation performance of the composites.Results Linear ablation rates of C/C-HfC-SiC and C/C-HfB2-HfC-SiC composites at 2200℃ were 1.54×10-3 mm/s and 1.38×10-3 mm/s respectively.Conclusion The composites had unique microstructural features, with nano-sized HfB2 and HfC particles uniformly distributed in SiC phase. The liquid-phase SiO2 and the solid-phase HfO2 composite oxides film in situ formed on the surface of the composites could resist not only the erosion of high-speed gas flow, but also the inward diffusion of oxidative gases, which was the main cause for the excellent ablation resistance of the composites at ultra-high temperature.