Copper Surface Coatings Formed by the Cold Spray Process: Simulations Based on Empirical and Phenomenological Data

Copper surface coatings produced by the cold spray process have been simulated by means of a two-dimensional computer simulation and compared with experimental data in terms of their porosity. During cold spray, solid state powders containing micrometer-sized particles are accelerated to supersonic velocities and fired onto a substrate, whereupon they undergo plastic deformation and subsequently adhere. Many factors may determine the resultant coating properties, among which include the particle size distribution, velocity, stagnation temperature, and pressure. The approach taken herein differs from those traditionally employed for modeling particle deformations and the subsequent formation of a surface coating. Such approaches rely heavily on the distribution of kinetic energy, elasticity, and fluidity of particles impacting the surface. Consequently, they are computationally impractical to simulate a bulk sample with statistical distributions of particle shape, size, and various experimental conditions. Rather than modeling the physical processes involved in particle deformations, our approach relies on correlating empirical and phenomenological statistical relationships of particle sizes and velocities obtained from experimental data to simulate coatings several hundreds of micrometers thick. In doing so, it enables the porosity of the coating to be related to both the temperature and particle size of the cold spray powders.