Calculation of Particle Parameters for Cold Spraying of Metal-Ceramic Mixtures

Formation of metal-ceramic composite coatings by cold spray is one of the major directions in the development and application of the technology. As experiments showed, addition of a hard ceramic component into the mixture can shift the transition from substrate erosion to particles adhesion closer to adhesion. This effect may be induced by ceramic particles which not only erode, but also activate the target surface. Velocity and temperature of particles at their high-velocity impact onto the substrate are governing parameters in particles/substrate interaction. These parameters influence both the process of metal particles deposition and the process of erosion/activation of the substrate surface by ceramic particles. Metallic and ceramic particles collide with each other in the gas stream. These collisions can produce preactivation effect on metal particles by cleaning their surface. The level of activation depends on a typical velocity of collision which is the difference between velocities of metal and ceramic particles. Parameters of metallic and ceramic particles in the gas stream are estimated. Calculations show that components of mixtures with fine abrasive particles have greatly different velocities that influences preactivation of metal particles. At the same time, the substrate surface is activated by fine abrasive particles characterized by a high-impact velocity.