Microstructure and Ablation Behavior of W/ZrC/SiC Coating on C/C Composites Prepared by Reactive Melt Infiltration and Atmospheric Plasma Spraying

A W/ZrC/SiC multilayer coating is prepared on carbon/carbon (C/C) composites by reactive melt infiltration (RMI) and atmospheric plasma spray (APS). The morphology and microstructure of the coating are characterized by scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD), and focused ion beam (FIB) and transmission electron microscopy (TEM). Microstructure analysis reveals that the gradient coatings exhibit smooth surface morphology, well-defined interfaces, uniform thickness, and a highly dense architecture. After 60 s of ablation, the linear ablation rates (LARs) and mass ablation rates (MARs) of the coated composites stand at 2.58 x 10(-3) mm s(-1) and 5.25 x 10(-3) g s(-1), respectively. In general, the reason for the great ablation resistance of W/ZrC/SiC-coated C/C composites is the comprehensive effect of the multilayer coating. The outer W coating is used as the first barrier layer to resist most thermal shocks. Then, the molten eutectics SiO2-ZrO2 formed in the ZrC/SiC layer at service temperature can fill the pores and act as a second diffusion barrier for oxygen and heat.