Supersonic flame ablation resistance of W/ZrC coating deposited on C/SiC composites by atmosphere plasma spraying

To improve the ablation resistance of C/SiC composites, in this study, double-layer coatings, with W as inner layer and ZrC as outer layer, were prepared by atmosphere plasma spraying. The coatings exhibited a dense structure, a good bonding with substrate and outstanding anti-ablation ability. After the coated composites were ablated at the distance of 100 mm for 60 s, the mass and linear ablation rates were 29.5×10^-2 g s^-1 and 5.33×10^-3 mm s^-1, decreasing by 38.2% and 56.7% respectively, compared with those of uncoated composites. The mechanical denudation played a principal role in the ablation of the ZrC outer layer. The gas release during ablation could take away a lot of heat. The melting of WO₃ could also consume lots of heat, and form a dense surface which was helpful to protect the composites. During the 200 mm ablation, WO ₃ needle-like crystals were formed.