Research Progress on Post-Treatment Technologies of Cold Spray Coatings

Cold spraying (CS), also known as cold gas dynamic spraying or supersonic cold spraying, is a process in which particles collide with the substrate at a speed greater than the critical value and deposit layer by layer to form a coating. As an emerging coating preparation technology that has been developed rapidly in recent years, CS is characterized by a low deposition temperature, a minimal thermal effect on substrate, and a high deposition efficiency. It has received extensive attention from industry. However, the inherent high strength and low plasticity of CS coatings and the numerous defects present limit their wider application to some extent. Therefore, various post-treatment technologies are successfully applied to the CS coatings to improve their comprehensive performance. This paper reviews the latest research progress of common post-treatment techniques for CS coatings, including five categories: thermal, mechanical, thermo-mechanical, chemical, and electrochemical processing. A considerable amount of experimental research has demonstrated that post-treatment can effectively enhance the microstructure and properties of CS coatings, and this can serve as a powerful approach to expand the application scope of CS technology. In addition, the relevant post-processing parameters and corresponding results are summarized and compared systematically.