Preparation and characteristics of thermal resistance polysiloxane/Al composite coatings with low infrared emissivity

Thermal resistance coatings with low infrared emissivity were prepared by using polysiloxane and aluminum as adhesives and paint, respectively. The influence of the solidification temperature, content of Al powders and coating thickness on the infrared emissivity of the composite coatings was systematically investigated. The chemical composition, surface microstructure and thickness of composite coatings were characterized and the thermal stability was studied. These results indicate that the emissivity changes significantly with increasing solidification temperature. The optimum content of Al powders is around 30 wt.%, and the lowest emissivity value is ∼0.19. The emissivity decreases rapidly with increasing thickness and reaches to a saturation value when d > 50 μm. Moreover, we found that the emissivity was almost unchanged with thermal stability test maintaining a low value 0.19 at temperature below 600 °C. The thermal stability study shows that the composite coatings exhibit favorable thermal ageing and good thermal shock resistance.