| Summary: | The paper discusses impact of solid and molten particles of a powder material in heterogeneous flow acting on solid surface and its effect on characteristics of coating applied by a gas-dynamic (cold spray) method. An equation of energy balance in impact zone of the particle on the substrate is given. Obtained equation accounts the particle size, mass average temperatures in heated portions of the particle and the substrate, before impact temperatures of the particle and the substrate, fraction of the heated mass of the particle and the substrate during impact, specific heat capacities of the particle and the substrate material, the Brinell characteristic, and deformation of a solid particle. Results of the bibliographic study of the molten metal droplet formation, their kicks in the substrate depending on its velocity, substrate temperature and surrounding gas pressure are presented. The differences in the impact mechanism of solid and molten particles on the substrate and their influence on the coating formation and its properties are determined. Recommendations for operating parameters of high-quality coating are given.
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