Effect of substrate temperature on interfacial bonding for cold spray of Ni onto Cu

Cold spray as a relatively new surface modification technique has great potential in the industry due to its ‘low working temperature’. The bonding quality between the cold-sprayed coating and the target substrate is one of the most important evaluation index for the coating performance. In this study, the interfacial bonding features between cold-sprayed Ni coatings and Cu are investigated to clarify the role of substrate temperature in the coating–substrate bonding. The finite element analysis model which can simulate the heat conduction through the coating–substrate interface is developed to model the particle deposition process on the substrate. The surface morphology and cross section of the experimentally deposited particles are observed by scanning electron microscope. The substrate surface oxidization behavior and coating–substrate interfacial atomic mixture are evaluated through the energy-dispersive spectroscopy line scans. The results indicate that heat conduction from the high-temperature substrate plays an important role in heating the interfacial region. The increased interfacial temperature significantly enhances the metallurgical bonding by improving the coating–substrate atomic mixture at the interface. Besides, the high-temperature substrate is also found to result in prominent metal jet and strong mechanical interlock due to the enhanced thermal softening effect. As a consequence, coating mass and coating–substrate bonding strength are promoted by using the high-temperature substrate.