Microstructure, surface stress and surface temperature response of ZrB2-SiC based coatings

SiC/ZrB2-SiC, SiC/ZrB2-SiC/SiC, SiC/ZrB2-SiC/ZrB2 and SiC/ZrB2-SiC/ZrB2/SiC coatings were prepared on graphite by pack cementation and chemical vapor deposition (CVD). The microstructure, surface stress, ablation resistance and surface temperature response during ablation of these coatings were systematically studied. The results indicated that pack cemented SiC/ZrB2-SiC coating can effectively relax mismatch between graphite substrate and outer dense coatings. The CVD ZrB2 layer with loose structure can further increase the compressive stress of outer CVD SiC layer, and avoid the formation of cracks in SiC layer. The surface temperature response during ablation is mainly affected by coating microstructure evolution and emissivity of different components. (C) 2020 Elsevier B.V. All rights reserved.