Abstract
Aluminum coatings were deposited onto Al7075 T651 structural alloy using both cold spraying and arc spraying. Arc spray coatings were produced using optimized parameters for two atomizing gases, namely air and nitrogen. Cold spray coatings were produced using a low pressure system with air and nitrogen as propelling gases. Six surface preparation procedures prior to deposition were evaluated. Interface quality of as-deposited coatings was investigated by means of fluorescent dye interface penetration technique, bond strength testing and backscattered electron microscopy. Environmentally assisted cracking tests were performed to study the corrosion protection capability of the resulting coatings for structural applications. Micrographs of samples taken before and after cyclic load testing in salt water immersion were compared. The results demonstrated that the Al coatings produced by both arc spray and cold spray provide to Al7075 alloy a cathodic protection against cracking and localized corrosion. However, to obtain such coating properties arc spray technique required advanced surface preparation prior to deposition. For cold spray, the surface preparation has minimal influence on the coating properties thus making this process more advantageous than arc spraying for this application.
