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.