Residual stress and thermo-mechanical properties of cold spray metal coatings

The residual stress profiles in Cu and Al coatings cold sprayed using kinetic metallization have been studied using neutron diffraction. To interpret results and to describe them quantitatively, the measured profiles were fit to Tsui and Clyne’s progressive coating deposition model, which demonstrated that the residual stresses are largely due to kinetic and not thermal effects. The residual stress state of the coatings was found to depend mainly on the deformation behaviour and properties of the coating material, and the kinetic parameters of the cold spray process. Young’s modulus and impact strain were measured and used along with published material data for Cu and Al to approximate the residual stresses, using a model developed for shot peening. The properties of the Cu coatings such as Young’s modulus and porosity were found to be closer to their bulk values than in the case of the Al coatings, and this was related to the amount of particle deformation on impact.