Characteristics of Thermal Control Plasma Electrolytic Coatings on Aluminum Alloy

Resumo

The structure and properties of thermal control white and black coatings for space applications on AMg3 aluminum alloy, obtained by plasma electrolytic oxidation in silicate–alkaline electrolytes, are studied experimentally. The composition and structure of the coatings are studied using scanning electron microscopy, energy-dispersive microanalysis, and X-ray diffraction analysis. It is found that aluminosilicates dominate in the porous structure of the white slightly conductive coatings, while vanadium is present in the black coatings. The solar absorbance A_s and thermal emissivity ε are measured: A_s = 0.28, ε = 0.93 for the white coatings and A_s = 0.95, ε = 0.88 for the black coatings. These values correspond to the characteristics of EKOM thermal control paint coatings produced by Kompozit (Russia). The effect of atomic oxygen flux on the coatings under investigation leads to insignificant erosion of their surface, as compared to other materials.