Investigation of the Substrate Rotation Speed Effect on the Morphology and Tribo-Mechanical Behavior of CrAlN Thin Films Using DC Magnetron Sputtering

In this work, CrAlN thin films were used to improve the lifespan of cutting tools. The CrAlN thin films were deposited on X50CrMoV8 substrates and silicon using DC reactive magnetron sputtering. The influence of substrate rotation speed (varied between 0.5 and 3 rpm) on the morphology, mechanical properties, and tribological properties of the thin films was investigated. The results showed that this process parameter had no significant influence on chemical composition or morphology. Nevertheless, the mechanical properties were enhanced. Specifically, CrAlN hardness increased significantly with the rise in substrate rotation speed from 0.5 to 1.5 rpm. Additionally, the adhesion strength of CrAlN coatings followed the same trend as hardness. When the substrate rotation speed increased, the residual stress shifted from tensile to compressive. Changing the rotation speed did not affect the friction coefficient value but did impact wear resistance. Thin films deposited at 0.5 and 1 rpm exhibited the lowest wear resistance. Once the rotation speed increased, wear behavior improved significantly. The CrAlN thin film deposited at a substrate rotation speed of 1.5 rpm showed the best wear resistance along with the highest hardness and adhesion strength.