Abstract
This paper presents a numerical simulation of the cold gas-dynamic spraying process of Al-Zn-TiO₂ composite powder onto a steel substrate. Using computational fluid dynamics (CFD) in COMSOL Multiphysics, the characteristics of the gas flow in a de Laval nozzle and the particle dynamics are obtained for various spraying parameters. Optimal conditions are determined: gas pressure of approximately 0.6 MPa, temperature of ~600°C, nozzle-to-substrate distance of 15 mm, spray angle of 90°. At these conditions, particles reach supersonic velocities of approximately 500-600 m/s, sufficient for their deposition on steel. It is shown that increasing gas pressure and temperature facilitates particle acceleration and increases their impact energy, while excessively small or large spraying distances reduce the efficiency of the process. Simulation of the impact interaction of particles with the substrate revealed intense plastic deformation of the powders under optimal parameters, ensuring strong adhesion of the coating to the base. The results of the numerical experiment are consistent with the observed characteristics of dense and adhesion-strong coatings. It has been established that the proposed CFD model can be used as an effective tool for optimizing the parameters of cold gas-dynamic spraying of composite powders.