Investigation on the Reliability of a Thermal Protection System Based on Mullite Fiber Insulation Tiles Coated with MoSi2-borosilicate Glass in an Aerothermal-Vibration Coupling Environment

MoSi₂-borosilicate glass coatings with high emissivity were prepared on mullite fiber insulation tiles via a slurry technique to enhance surficial thermal radiation and serve in the thermal protection systems (TPS) for spacecraft vehicles. The ablation behaviors and structural reliability of the TPS were investigated using a novel aerothermal-vibration coupling test system. During the test, the heat flux ranged from 75 kW/m² to 213 kW/m², accompanied by random vibration with frequency range of 20–2000 Hz and root mean square of total acceleration (Grms) of 15.2 g. Results showed that surface temperatures of the TPS ranged from 601.2 °C to 1043.6 °C, while the maximum back-face temperature only reached 68.7 °C during testing. In addition to demonstrating superior thermal insulation performance, the designed TPS also exhibits exceptional structural reliability. Specifically, following the aerothermal-vibration coupling environmental assessment, the coating structure remains intact and the insulating tiles remain securely attached to the aluminum alloy substrate. This study provides a solution for obtaining excellent thermal insulation performance TPS with high structural reliability, which is urgently needed for spacecraft vehicles.