Effect of microblasting on cathodic arc evaporation CrN coatings

Abstract

Cathodic arc evaporation CrN double layer coatings were deposited onto tool steels in two steps by industrial apparatus. Microblasting was performed on CrN first layer in order to remove metallic droplets and surface defects and to promote the adhesion of the second layer. Surface morphology effects were assessed by a scanning electron microscope coupled with Image analyser software. Nanoindentation and scratch tests were performed to evaluate the changes of coating adhesion and mechanical properties. Structure, microstructure and residual stress were evaluated by X-ray diffraction. In particular, by means of Cu and Cr wavelengths, the residual stresse of both steel substrates and coatings was calculated. The results show that microblasting has no effect on coating hardness and slightly affects the adhesion of the coating to the substrate. On the other hand, microblasting increases coating resistance to cohesive failure and the substrate compressive stress at the coating interface.