High-pressure cold gas dynamic (CGD)-sprayed alumina-reinforced aluminum coatings for potential application as space construction material

• Al–Al2O3 composite coatings were deposited on Al 7579 substrates by CGDS.
• Low thermal conductivities were determined to be between 0.2 and 2.0 W/m °C.
• AO irradiation caused formation of a thin surface layer with higher oxygen content.
• Solar absorptance and thermal emittance showed solar absorber characteristics.

Alumina–aluminum MMC coatings were deposited by cold gas dynamic spraying onto aluminum alloy (Al 7570) substrates. The microstructure, phase composition, thermal conductivity, microhardness, and thermal optical properties (solar absorptance αs and thermal emittance ε) of four types of coating were determined on as-sprayed samples and samples subjected to atomic oxygen (AO) plasma, intended to simulate conditions in outer space environment. In addition, time-of-flight (ToF) secondary ion mass spectrometry (SIMS) was applied to determine the responses of the coatings to oxidation by AO plasma. The results indicate that the very low thermal conductivity (λ), low solar absorptance (αs), comparatively high infrared emittance (ε) and oxidation stability of the investigated coatings may provide adequate protection as environmental control coatings of space-bound materials against deleterious effects of space environment within the Low Earth Orbit (LEO) and beyond.