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

Abstract

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 × 10−3 mm s−1 and 5.25 × 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.