Mechanical characterization of low-pressure cold-sprayed metal coatings on aluminium

Metal coatings are widely used in order to improve the superficial properties of mechanical components or tools. Cold spray deposition is an attractive technology that allows to realize a reported coating on a metallic or polymeric surface. The essence of the phenomenon is that particles of ductile metals or alloys, having diameter of approximately 10-100 micron, become deformed and strongly attached to a surface when they impinge on the surface of metals, ceramics or glasses at impact velocities in the range of about 400-1200 m/s. In this manner, coatings can be formed on a substrate. In this work, mechanical tests were carried out in order to evaluate the adhesion of different metal particles on an aluminium alloy substrate, in order to characterize both the coating-substrate adhesion and the adhesion between two consecutive layers of the cold-sprayed metal coating. In particular, both bending tests and pure adhesion test were carried out in order to better understand the powder deposition mechanism. Bending tests were carried out in four-point bending configuration. On the basis of the experimental campaign, it results that the adhesion of the pure aluminum particles are very good, conversely the copper particles show a good adhesion on the aluminum substrate but have a low internal cohesion.