Exceptionally low ablation rates realized in the cellular-structured MCMB@WC composites via biomimetic design

Abstract

Thermal protection materials (TPMs) with extra-low ablation rate in long-term are ungently required in reusable spacecrafts. However, the ablation property and operation life of conventional graphite/carbon-based composites with ultra-high temperature ceramic coatings are rather limited. Inspired by the self-healing behavior of plants, we designed and fabricated cellular-structured tungsten carbide (WC) reinforced graphite composites via the combination of molten salt coating and spark plasma sintering. Owing to the intelligent biomimetic structure and regeneration of WC during the ablation process, the composites exhibited not only excellent thermal shock resistance but also exceptionally low ablation rates. In the cyclic ablation test under 4.18 MW·m−2 for 360 s, the linear and mass ablation rates of the composite at the last ablation period decreased to 0.33 mg·s−1 and 0.17 μm·s−1, respectively. The biomimetic structural design offers new insights for fabricating graphite-based composites with exceptionally low ablation rates, which are promisingly applied in reusable spacecrafts.