Studies on anodic oxide coating with low absorptance and high emittance on aluminum alloy 2024

Anodization of AA 2024 in sulfuric acid bath containing glycerol, lactic acid and ammonium metavenadate has been studied to develop white anodic oxide coating. Investigation on the influence of various operating parameters — coating thickness, current density and ammonium metavenadate concentration on the optical properties was carried out to optimize the process. Infrared, atomic absorption spectroscopic techniques and scanning electron micrograph were used to characterize the coating. The obtained oxide coating provides a ratio of solar absorptance (α) to infrared emittance (ε), as low as 0.2. The optical properties and hardness values measured under optimum experimental conditions support its use as a thermal control coating.