High-Emissivity Double-Layer ZrB 2 -Modified Coating on Flexible Aluminum Silicate Fiber Fabric with Enhanced Oxidation Resistance and Tensile Strength.

Fibers crystallize and become brittle at high temperatures for a long time, so the surface coating must maintain long-lasting emission performance, which requires superior antioxidant properties of the high-emissivity fillers. To improve the radiation performance of the coating and the tensile strength of the fiber fabric, a double-layer coating with high emissivity was prepared on the surface of flexible aluminum silicate fiber fabric (ASFF) using MoSi ₂ and SiC as emissive agents. The incorporation of borosilicate glass into the outer coating during high-temperature oxidation of ZrB ₂ results in superior encapsulation of emitter particles, effectively filling the pores of the coating and significantly reducing the oxidation rate of MoSi ₂ and SiC. Furthermore, the addition of an intermediate ZrO ₂ layer enhances the fiber bundle's toughness. The obtained double-coated ASFF exhibits an exceptionally high tensile strength of 57.6 MPa and a high bond strength of 156.2 kPa. After being subjected to a 3 h heating process, the emissivity exhibits a minimal decrease of only 0.032, while still maintaining a high value above 0.9. The thermal insulation composites, consisting of a flexible ASFF matrix and a ZrB ₂ -modified double-layer coating, exhibit significant potential for broad applications in the field of thermal protection.