High-emissivity coatings on flexible fibrous fabrics are promising thermal-insulation materials for thermal protection systems in hypersonic vehicles. However, the interfacial bonding strength between the high-emissivity coating and the flexible fibrous substrate remains a critical challenge. A high-emissivity double-layer TiO2 interlayer modified by metal ions (Mg2+, Co2+, Ni2+, and Zn2+) with high-entropy (M2+@TiO2-HE) coating was developed on an aluminosilicate fiber fabric. The interlayer of the M2+@TiO2-HE coating not only enhances bonding strength through mechanical interlocking but also improves thermal insulation performance by acting as an infrared reflective layer. The bonding strength between the M2+@TiO2-HE coating and the ASFF substrate showed an 183% enhancement compared to that of the single-layer high-emissivity high-entropy coating. Under one-sided heating at 1400 °C, the backside temperature of the coated ASFF stabilizes at 330 °C, which is approximately 50 °C lower than that of the sample with the single-layer high-emissivity high-entropy coating. In the wavelength range of 0.3–2.0 μm, the average reflectivity of the M2+@TiO2 coating was 0.70, and in the wavelength range of 1–14 μm, the average emissivity of the M2+@TiO2-HE coating was 0.89. The M2+@TiO2-HE coating with high emissivity and reflectivity enhances both the bonding strength and thermal insulation performance of ASFF, showing its potential for applications in aerospace thermal protection systems.
Xu et al. (Sun,) studied this question.