Comparative analysis of oxidation resistance at 1700 °C for HfB2-SiC-MoSi2 coatings on curved C/C composites prepared via gaseous and liquid silicon infiltration
Shubo Zhang, Zhiqiang Liu, Shuo Zhang, Xiaoxuan Su, Qiangang Fu
Abstract
To investigate the differences in densification effects and oxidation resistance of curved samples subjected to gaseous and liquid Si infiltration, HfB 2 -SiC-MoSi 2 -Si/SiC-Si coated C/C composites are prepared using gaseous and liquid Si infiltration (G-HSM and L-HSM), respectively. The mass change rates of G-HSM and L-HSM after thermal shock from 1700 °C to room temperature are −2.52 % and 0.07 %. After isothermal oxidation at 1700 °C for 200 h, the mass change rate of L-HSM is −0.12 %, while that of G-HSM reaches −0.60 % after 124 h. The high content of HfB 2 and MoSi 2 in L-HSM improves the coating stability, which effectively avoids droplet shedding. In addition, the lower roughness and narrower original cracks reduce oxygen adsorption sites and diffusion channels of L-HSM during oxidation. Thus, L-HSM exhibits better thermal shock resistance and oxidation resistance than G-HSM. This study provides a strategy for the coating design of curved components above 1700 °C.