Ablation Experiments of Ultra-High-Temperature Ceramic Coating on Carbon–Carbon Composite Using ICP Plasma Wind Tunnel

Abstract

Ablation experiments of four thermal protection system (TPS) candidate specimens, including two UHTCs-coated (HfC and HfC–TiC) specimens, were performed. The specimens were tested at the VKI’s 1.2 MW ICP plasma wind tunnel. Intrusive flow diagnostic techniques (calorimetric probe and Pitot tube) were used to experimentally determine cold wall heat flux and dynamic pressure. Using the wind tunnel operating conditions and the experimental results, numerical codes were solved to characterize the boundary edge conditions. During tests, the specimen wall temperatures were measured optically using a two-colour pyrometer and the specimen internal temperatures were measured using thermocouples. The specimen surface feature changes were determined by three-dimensional mapping of specimen surfaces. The cold wall heat fluxes and dynamic pressure values for tests were in the range from 4.05 to 4.26 MW/m2 and 2.57 to 2.67 mbar, respectively. Two UHTC-coated specimens’ peak wall temperatures were almost 3000 K. The UHTC-coated specimens exhibited surface inflation, i.e., volume increase and the respective mass changes were very small compared to non-UHTC-coated specimens. HfC–TiC specimen’s mass change was positive, contrary to other specimens. The overall performance of HfC–TiC-coated specimen was better than others. TiC layer is considered as the reason for the mass increase and better overall performance.