Ablation Resistance of APS Sprayed Mullite/ZrB 2 -MoSi 2 Coating for Carbon/Carbon Composites

Abstract Mullite/ZrB 2 -MoSi 2 coating was deposited on carbon/carbon(C/C) composites to protect against ablation by atmospheric plasma spraying (APS). The microstructure and morphology of the coating were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The ablation resistance of the coating was investigated at different temperatures with oxypropylene torch. The results show that the mass ablation rates of the Mullite/ZrB 2 -MoSi 2 coated C/C composites are 3.49×10 −3 g/s and 3.77×10 −3 g/s after ablation at 1700 and 1800 °C for 60 s, respectively, which exhibit good ablation resistance compared with the single-layer ZrB 2 -MoSi 2 coated. The increase of ablation resistance can be attributed to the formation of a silicates glass film, which acts as a thermal barrier and self-seals the defects of the coatings.