Ablation Behavior of HfC and TaC Coatings Prepared By Vacuum Plasma Spraying for Carbon/Carbon Composite Protection

Ultra-high temperature ceramics such as hafnium carbide (HfC) and tantalum carbide (TaC) were coated using vacuum plasma spray (VPS) to protect the carbon/carbon (C/C) composite starting oxidation at a relatively low temperature about 500 °C. The top surface of C/C composite was coated with silicon carbide (about 30 µm) in advance by chemical vapor reaction (CVR) to improve adhesion between coating layer and substrate. To coat HfC and TaC of 100 µm thickness on C/C composite, the operational parameters of VPS such as input power, gas composition and spray distance were optimized. The ablation test of the coated HfC and TaC was performed using high velocity oxygen fuel (HVOF) to evaluate the heat/ablation resistance properties and showed good performances for C/C composite protection without any damages. However, the HfC and TaC showed different ablation/oxidation behavior because of the different composition and crystallinity in coated layers. The composition and microstructure of the HfC and TaC coating layers were also characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), respectively.

This research was supported by Korea Basic Science Institute (National research Facilities and Equipment Center) grant funded by the Ministry of Education. (2021R1A6C101B383)