Theoretical Study of Powder Particle Parameters in a Modified Cold Spray Nozzle

Abstract

The article aims to understand the influence of the nozzle channel geometry on the temperature and velocity parameters of the sprayed particles and the possibility of controlling the process parameters to improve the physical and mechanical characteristics of the resulting coatings. The paper presents the results of calculations of the temperature and velocity of aluminum and nickel particles in the channel of a supersonic nozzle for cold spraying. The study was conducted for two nozzles – the standard one used in DYMET low-pressure units and its modification. The calculations were performed using a well-known one-dimensional gas-dynamic model. The study was conducted in two stages. First, the flow characteristics in the nozzle were calculated based on the known values of the temperature and air pressure at the nozzle inlet and the known values of the cross-sectional area at each point along the nozzle. The next step was to calculate the particle velocity and temperature. The scientific novelty is the following: the effect of modified nozzle geometry on aluminum and nickel particles velocity and temperature at the nozzle exit is shown compared to the results for standard low-pressure cold spray nozzle. The practical value is that obtained results can be used to develop recommendations for aluminum and nickel powders’ cold spray deposition of restorative and protective coatings with improved characteristics using the modified nozzle.