Corrosion characteristics and wear performance of cold sprayed coatings of reinforced Al deposited onto friction stir welded AA2024-T3 joints

A pure Al coating and Al based composite coating reinforced with 20 vol% Al₂O₃ particles were deposited onto a friction stir welded AA2024-T3 joint substrate. The effects of hard Al₂O₃ particles on the coating microstructure, electrochemical behavior and wear performance were investigated. Microstructural analysis shows that the addition of ceramic particles enhances the coating density. Results of electrochemical tests show that both the Al-20 vol% Al₂O₃ composite coating and pure Al coating provide cathodic protection to the friction stir welded joint substrate. The Al-20 vol% Al₂O₃ composite coating shows higher corrosion current density than the pure Al coating due to the inter-particle (between Al₂O₃ and Al particles) boundaries and the severer plastic deformation of Al particles accelerating the corrosion reaction. The presence of Al₂O₃ particles in Al matrix improves the coating wear resistance and changes the wear mode from abrasive wear to adhesive one when compared to the unreinforced pure Al coating.