Research on HfC Coating Performance and Preparation Process
ZHANG Mao, GAO Qinqin, WEI Yan, CAI Hongzhong, ZHANG Guixue, WANG Xian, WANG Xingqiang, HU Changyi
State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals,
Kunming Institute of Precious Metals, Kunming 650106, China
Carbon-based composite materials (C/C, C/SiC) have high specific strength, high specific modulus, low density, low thermal expansion coefficient, corrosion resistance, thermal shock resistance, and are considered as one of the most promising high temperature structural materials. However, carbon-based composites generally begin to oxidize at 500 ℃, and have large porosity, which cannot achieve high pressure sealing, which greatly limits the application prospects ofcarbon-based composites. Under the environment of high temperature and high pressure air scour, ultra high temperature ceramic base protective coating can effectively inhibit carbon composite material (C/C, C/SiC) in the degradation of carbon composition. The melting point of hafnium carbide (HfC) is as high as 3890 ℃, which is the highest in the known single compound, the thermal conductivity is only 5.6 W/(m · K), Vickers hardness is as high as 26 GPa, good ablative resistance, but also has low thermal conductivity, low oxygen diffusion coefficient, low surface vapor pressure. Oxidation resistant ablative coatings have been used as extremely heat resistant components such as rocket nozzles and nose cones. In this paper, the research background, basic properties, preparation technology, ablation mechanism and coefficient of thermal expansion are summarized. The current challenges of ultra temperature ceramic HfC coatings are pointed out, and the development trend of ultra temperature ceramic HfC coatings is forecasted.