Surface treatments are applied to aluminum castings to provide a decorative finish, to form a protective barrier against environmental exposure, and to improve resistance to wear.
Decorative finishes can be applied to aluminum castings through painting, powder coat finishing, polishing, epoxy finishing, and plating.
Aluminum can be plated by applying an initial immersion zinc coating, followed by conventional copper-nickel chromium plating procedure similar to that used for plating zinc metal/alloys. Protection against environmental corrosion for aluminum die castings is achieved through painting, anodizing, chromating, and iridite coatings. Improved wear resistance can be achieved with aluminum die castings by hard anodizing.