Microstructure and corrosion properties of Cu coatings deposited via laser-assisted low-pressure cold spray
(1. College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China;
2. Institute of Laser Advanced Manufacturing, Zhejiang University of Technology, Hangzhou 310023, China;
3. Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Zhejiang University of Technology, Hangzhou 310023, China;
4. Zhejiang Reci Laser Technology Co., Ltd., Taizhou 317500, China)
2. Institute of Laser Advanced Manufacturing, Zhejiang University of Technology, Hangzhou 310023, China;
3. Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Zhejiang University of Technology, Hangzhou 310023, China;
4. Zhejiang Reci Laser Technology Co., Ltd., Taizhou 317500, China)
Abstract: Cu coatings were prepared via the laser-assisted low-pressure cold spray (LPCS) method to study the effect of laser irradiation on microstructure and corrosion behaviors of the coatings. The results reveal that the laser-assisted LPCS-Cu coatings are denser and have better coating-substrate interfacial bonding as compared to LPCS-Cu coating. Laser irradiation improves the overall plastic deformation of deposited particles, resulting in uniform grain refinement of Cu particles. Therefore, the laser-assisted LPCS-Cu coatings show more uniform microstructure and smaller grain size. The results of electrochemical tests demonstrated that laser-assisted LPCS-Cu coatings have higher corrosion potential, lower corrosion current and corrosion rate than the LPCS-Cu coating in 3.5 wt.% NaCl solution. The main reason is that laser irradiation improves the coating density and intimate bonding between particles, and a continuous and dense corrosion product film composed of CuCl and Cu2O is formed on the surface of the laser-assisted LPCS-Cu coating to block the erosion of the corrosive solution.
Key words: Cu coating; laser irradiation; cold spray; microstructure; corrosion properties