Nozzle Geometry and Particle Size Influence on the Behavior of Low Pressure Cold Sprayed Hydroxyapatite Particles

Abstract

Low-pressure cold spray (LPCS) technology has attracted interest for the deposition of ceramic coatings due to the thermo-kinetic conditions experienced by the sprayed particles. Unlike conventional thermal spray techniques, the spraying conditions in LPCS can be controlled to avoid the formation of undesired phases. However, ceramics deposition through this process is still challenging. The present study includes a finite element analysis and simulation study of the kinetic conditions of ceramic particles in the LPCS process based on experimental data. The analysis seeks to discuss the effect of nozzle geometry on the kinetic and thermal energy of the sprayed particles at impact and elucidate how the particle travels within the high-velocity jet to be deposited onto a metallic surface. This work examines the behavior of hydroxyapatite particles as a function of particle size and nozzle geometry during LPCS deposition. Interestingly, the results from this research suggest that particle size and nozzle geometry have an influence on the deposition of hydroxyapatite particles. Inertia of large particles proved to be beneficial in keeping their trajectories, allowing them to contribute to the formation of the coatings. Nozzle geometry modifications produced changes in the jet profile and affected the homogeneity of the coatings obtained. This finding contributes to a better understanding of the deposition of hydroxyapatite particles by cold spraying.