PROCESSES TO REDUCE INTERFACIAL ENRICHMENT OF ALLOYING ELEMENTS UNDER ANODIC OXIDE FILMS AND IMPROVE ANODIZED APPEARANCE OF HEAT TREATABLE ALLOYS

摘要

Anodic oxide coatings and methods for forming anodic oxide coatings on metal alloy substrates are disclosed. Methods involve post-anodizing processes that improve the appearance of the anodic oxide coating or increase the strength of the underlying metal alloy substrates. In some embodiments, a diffusion promoting process is used to promote diffusion of one or more types of alloying elements enriched at an interface between the anodic oxide coating and the metal alloy substrate away from the interface. The diffusion promoting process can increase an adhesion strength of the anodic oxide film to the metal alloy substrate and reduce an amount of discoloration due to the enriched alloying elements. In some embodiments, a post-anodizing age hardening process is used to increase the strength of the metal alloy substrate and to improve cosmetics of the anodic oxide coatings.

主权项

1. An enclosure for an electronic device, comprising:
an aluminum alloy substrate characterized as having a prescribed concentration of zinc as an alloying element; and an anodic oxide film disposed on a surface of the aluminum alloy substrate, wherein an enrichment layer defined by a two nanometer thick region of the aluminum alloy substrate adjacent the anodic oxide film has concentration of at least the prescribed concentration of zinc and no more than 3 weight percent of zinc.