MoSi₂ addition for high ablation resistance of dense ZrB₂-based composite coating prepared by very low-pressure plasma spraying

Dense ZrB₂-MoSi₂ coatings were deposited on SiC-coated C/C composites for ablation protection by very low-pressure plasma spraying with mechanically mixed ZrB₂ with 10–20 vol% MoSi₂. The 100 Pa low chamber pressure ensures a dense coating with porosity down to 2.5%. During the ablation, the added MoSi₂ produces a solid oxygen-blocking MoB layer and liquid self-sealing SiO₂. Both could effectively block the oxygen penetration and results in 10 times improved ablation resistance as compared with the pure ZrB₂ coating.