Particle/substrate interaction and coating structure formation during detonation spraying of copper powder on steel

Detonation spraying is commonly used to form protective and functional coatings. The influence of the temperature and velocity of spraying particles on the quality of the coatings is frequently analyzed by the study of single splats. However, to date, there has been limited research on the interaction and structure formation at the splat/substrate interface during detonation spraying. In this paper, copper splats and coatings were formed on steel substrates using three different spraying modes: 'cold', 'normal', and 'hot'. The features of the particle/substrate interaction were studied experimentally and by numerical simulation using the smoothed particle hydrodynamics (SPH) method. The simulation revealed the deformation and temperature history of the particles and substrate during impact. The structure of the splats and coatings was characterized using scanning electron microscopy (SEM) and synchrotron X-ray diffraction (SXRD). The microstructure of the coatings sprayed in the 'normal' and 'hot' modes consists of columnar crystals, indicating complete melting of the particles. The coating obtained in the 'cold' mode consists of a mixture of molten, partially molten, and unmolten particles. SXRD analysis revealed an increase in dislocation density in the sprayed coatings compared to the initial powder. The sprayed material mainly contains screw dislocations, while the initial powder predominantly contains edge dislocations. The approach used, combining materials characterization techniques and numerical simulation, has great potential for analyzing the coating formation process and can be applied to the optimization of thermal spraying parameters of various materials. The results of this study may be of interest to other researchers working in the field of thermal spraying of copper-based alloys.