A High-Emissivity Coating Comprising Chromium–Aluminum Phosphate for Thermal Protection at High Temperatures

High-emission coatings are the focus of significant attention for their efficient thermal protection in aerospace applications. Aluminum–chromium phosphate solution (ACP) was synthesized in this study by utilizing H₃PO₄, Al(OH)₃, CrO_3, and CH₃OH as raw materials. Subsequently, a room-temperature curing high-emissivity coating was effectively developed by employing ACP as the binder, Mg-MOF-74 as the curing agent, SiC and ZrB₂ as radiating agents, and Al₂O₃ and ZrO₂ as high-temperature stabilizers. Consequently, the coating exhibited exceptional thermal stability and radiation performance, with a mass residue rate of 98.71% after exposure to 1500°C. And the emissivity exceeded 0.93 at room temperature and measured ε _{(3–8 µm)} = 0.84 and ε _{(8–18 µm)} = 0.9 after treatment at 1200°C. Thus, the coating developed in this study provides durable and highly effective thermal protection under high-temperature conditions.