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

Abstract

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.