The electrical conductivity of anodized aluminum thermal control coating will be enhanced by deposition of an electronically conductive metal oxide within the anodic oxide pores. The electrical charge that might otherwise accumulate on its surface in the ambient space plasma will leak off through the coating. This will prevent structural damage from sputtering of the alloy substrate at coating breaks, and minimize electrical noise. In a previous study processes were developed to deposit the conductive oxide, MnO2, in the anodized coating. It was found to cause only minimal increase in coating absorptivity, and satisfactory electrical conductivity was obtained when measured with a metallic contact. But in a simulated space plasma environment these same coatings had poor conductivity. Subsequent examination showed that the conductive pores were highly localized, and this is likely to have caused poor coupling between the coating and plasma. We will develop new deposition processes to produce a more uniform distribution of conductive pores, so that all parts of the surface will have similar access to conductive channels. This will improve coupling in the space plasma and increase conductivity. Feasibility will be established by measuring electrical properties of coated specimens in vacuum plasma.
Potential Commercial Applications:Conductive anodized coatings can be used as low cost thermal control coatings for commercial satellites, such as for communications, and will provide improved performance by reducing noise from arcing associated with accumulation and discharge of surface charge.
