An optimized strategy toward multilayer ablation coating for SiC-coated carbon/carbon composites based on experiment and simulation

Abstract

Carbon/carbon (C/C) composites are widely used as thermal protection systems for atmospheric re-entry, where they are subjected to strong oxidation and mechanical denudation. Sublayer thickness of multilayer coating has considerable influence on its stress, which further governs their service life in critical environments. In this study, a multilayer coating with different sublayer thicknesses was fabricated on SiC-coated C/C composites using plasma spraying. Prior to the fabrication, finite element analysis (FEA) was firstly established to investigate the relationship between sublayer thickness and thermal stress. Thereafter, the coatings with typical sublayer thickness were verified through practical experiments. Raman spectra and ablated appearances showed well coincidence with the FEA results, pointing out close relationship among sublayer thickness, residual stress and ablation behavior. After testing for 90 s, the sample with optimized thickness owned the least stress (294 MPa) and lowest ablation rates (−0.467 µm/s and −0.343 mg/s) as compared to other coated ones.