Chromic acid anodizing of aluminum foil

The success of the Space Station graphite/epoxy truss structure depends on its ability to endure long-term exposure to the LEO environment, primarily the effects of atomic oxygen and the temperture cycling resulting from the 94 minute orbit. This report describes the development and evaluation of chromic acid anodized (CAA) aluminum foil as protective coatings for these composite tubes. Included are: development of solar absorptance and thermal emittance properties required of Al foil and development of CAA parameters to achieve these optical properties; developing techniques to CAA 25 ft lengths of Al foil; developing bonding processes for wrapping the Al foil to graphite/epoxy tubes; and atomic oxygen testing of the CAA Al foil. Two specifications were developed and are included in the report: Chromic Acid Anodizing of Aluminum Foil Process Specification and Bonding of Anodized Aluminum Foil to Graphite/Epoxy Tubes. Results show that CAA Al foil provides and excellent protective and thermal control coating for the Space Station truss structure.