Grain growth limitation in the monolayer ZrB2-SiC coating above 1700 °C

The cracking behavior along the interface (surface ZrO2 layer and unoxidized ZrB2-SiC layer) in the thermally sprayed ZrB2-SiC coating above 1700 degrees C was investigated by cyclic ablation tests (2.4 MW/m(2)). Experiment and simulation results show that the rapid growth of surface ZrO2 grains will greatly promote the interfacial micropores development until the formation of inter-laminar cracks. To address this issue, the laminated ZrB2-SiC/ZrO2 coating was prepared. The ZrO2 interface layer effectively restrained surface ZrO2 grain growth and improved the structural integrity by hindering the diffusion of liquid B2O3 and SiO2 towards the surface. Compared with monolayer ZrB2-SiC coating (-0.17 mg/s and -8.13 mu m/s), the mass and linear variation rates of the laminated coating decreased by 35% and 60%, respectively.

Automated summary

This study investigated the cracking behavior along the interface in thermally sprayed ZrB2-SiC coating at high temperatures and proposed a laminated coating solution to improve structural integrity by restraining surface ZrO2 grain growth.