Correlation between the macroscopic adhesion strength of cold spray coating and the microscopic single-particle bonding behaviour: Simulation, experiment and prediction

Abstract

Metal cold spray is an emerging coating technology with wide applications in surface functionalization and localized repair. However, the coating fabricated by this process suffers from low adhesion strength and brittle material behaviour. Therefore, process optimization through finite element simulation and experimental trials are much needed. In the current study, a semi-empirical equation is proposed to predict the macroscopic adhesion strength of the coating by linking the second-order derivative of the local nodal temperature history with the strength of dynamically recrystallized nanograin layer in the vicinity of the node at the particle-substrate interface. This work provides the first attempt to predict the coating adhesion strength with experimental validation, which is a useful tool for the engineers to examine the influence of individual process parameter on the adhesion strength. It is shown that the temperature of the particle plays the most important role in influencing the coating adhesion strength, followed by the particle impact speed. Moreover, increasing the substrate temperature may have an adverse effect on the adhesion strength. The window of deposition is likely to exist for the substrate temperature control.