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

Area of Science:

• Materials Science
• Aerospace Engineering
• Surface Chemistry

Background:

• High-emissivity coatings are crucial for thermal management in aerospace.
• Existing coatings often face limitations in thermal stability and emissivity at extreme temperatures.

Purpose of the Study:

• To synthesize a novel aluminum-chromium phosphate solution (ACP).
• To develop a room-temperature curing, high-emissivity coating with enhanced thermal stability and radiation performance for aerospace applications.

Main Methods:

• Synthesized ACP using phosphoric acid, aluminum hydroxide, chromium trioxide, and methanol.
• Formulated a coating using ACP binder, Mg-MOF-74 curing agent, SiC and ZrB2 radiating agents, and Al2O3/ZrO2 stabilizers.
• Evaluated thermal stability via high-temperature exposure (up to 1500°C) and measured emissivity across different temperature ranges.

Main Results:

• The developed coating demonstrated excellent thermal stability, retaining 98.71% mass after 1500°C exposure.
• Achieved high emissivity (>0.93 at room temperature).
• Post-1200°C treatment, emissivity measured ε(3-8 µm)=0.84 and ε(8-18 µm)=0.9.

Conclusions:

• The novel coating provides durable and highly effective thermal protection.
• The formulation offers a promising solution for demanding aerospace thermal management challenges.
• The room-temperature curing aspect simplifies application processes.