What methods are used to protect aluminum from corrosion?

Aluminum corrosion protection uses multiple approaches: Surface treatments: Anodizing (MIL-A-8625) - Electrochemical oxide layer, Type I (chromic), Type II (sulfuric), Type III (hard coat); Chromate conversion (MIL-DTL-5541) - Chemical treatment, excellent paint adhesion (being phased out); Non-chromate alternatives - Trivalent chrome, Ti/Zr-based (NAVAIR qualified). Coatings: Primers - Epoxy, polyurethane with corrosion inhibiting pigments (zinc chromate being replaced); Topcoats - Polyurethane, epoxy for environmental protection; and Sealants - Polysulfide at joints, fasteners. Design practices: Drainage provisions (no water traps), Isolation from dissimilar metals, Sealants at interfaces, and Access for inspection. Temper selection: -T7 tempers for 7xxx reduce SCC susceptibility. Clad aluminum: Pure aluminum surface layer on 2xxx/7xxx, Sacrificial protection. Protection system selected based on environment severity, design life, and maintenance access. Coating systems qualified per military or OEM specifications.