Phase and microstructure evolutions of in-situ ZrC composite coating under plasma torch ablation

A ZrC anti-ablation composite coating was prepared by introducing the chemical reaction between Zr and SiC to atmospheric plasma spraying. The as-prepared ZrC coating could provide desirable protection for 20 s ablation and the phase identification results shown that the oxide layer formed after the ablation process was mainly composed of tetragonal zirconia (higher than 50 wt%). The microstructure evolution of the ablated coating surface was clearly revealed. It is demonstrated that zirconia and silica shown good compatibility and cooperation after 15 s ablation and dense Zr-Si-O anti-ablation layer was formed. It could be attributed to the intimate and homogenous distribution of in-situ nanostructured ZrC and silicide phases in the as-prepared coating. The maintenance of meta-stable zirconia in the oxide layer could be attributed to the smaller grain size and compact arrangement of the zirconia particles. •Dense ZrC-ZrSi2-SiC composite coating was reactively synthesized.•Tetragonal zirconia was observed in compact Zr-Si-O oxide layer.•Novel ablation mechanism was raised for fine-grained ZrC phase.