Thermal insulation and structural reliability of modified epoxy resin-based ablation thermal protection coatings in aerothermal-vibration coupling environment

Novel hybrid ablation thermal protection coatings (FHMP-ATPCs), employing iron trioxide (Fe₂O₃) powder, hollow glass microspheres, and mica powder as the fillers in hydroxyl-terminated silicone oligomer-bridged epoxy resins (PSG) copolymer, is investigated using an aerothermal-vibration coupling test system. The ablation behavior and structural reliability of FHMP-ATPCs with varying coating thickness were studied. During the test, the total enthalpy of airflow and dynamic pressures are 23 MJ/kg and 300 Pa, accompanied by the random vibration with a frequency of 20–2000 Hz and a total root-mean-square acceleration of 14.9g. The maximum surface and back-face temperatures of the coating with the thickness of 2 mm reached 836.2°C and 156.4°C, respectively. Results also showed that the reduction of thickness obviously suppressed the surface temperature and increase in back-face temperature yet maintaining high structural reliability. Compared with DGEBA-based coatings, the PSG-based coatings showed excellent structural reliability during the test. The study provides a solution for obtaining high performance ATPCs, which are highly desired for supersonic vehicles.