Ablation-resistant Ir/Re coating on C/C composites at ultra-high temperatures

Abstract

An iridium/rhenium (Ir/Re) double-layer coating was prepared on carbon/carbon (C/C) composites by chemical vapor deposition (CVD) and electrodeposition. The morphologies and bond strengths of the coatings on the C/C substrate were examined. The ablation resistance of the Ir/Re coating was studied at 1800°C in an oxyacetylene torch flame for 300 s. The results show that Re interlayer increases the bond strength between Ir coating and C/C substrate by over 100 %. During entire hightemperature ablation process, Ir/Re coating keeps intact without any signs of ablation damage. Ir coating gets smoother and the grain size becomes larger after ablation, with the preferred orientation changing from 311 h i to 220 h i: Although some voids are observed along the grain boundaries of the as-ablated Ir coating, Ir/Re coating keeps intact on C/C composites. The study indicates that Ir/Re coating can provide good ablation resistance up to 1800°C for C/C composites, especially for the continuous ablation applications.