Influence of laser substrate pretreatment on anti-adhesive wear properties of WC/Co-based TiAlN coatings against AISI 316 stainless steel

Abstract

To improve the anti-adhesive wear properties of WC/Co-based TiAlN coatings, a laser substrate surface pretreatment was examined. The cemented carbide substrates were textured with a Nd:YAG laser, in three different scanning speeds, and then coated with a PVD TiAlN film. The anti-adhesive wear properties of each surface were evaluated via the ball-on-disk wear test and turning experiments. Additionally, characterization tests such as variable depth scratch test were also performed in order to verify the coating adhesiveness and to explain the results of the wear and machining tests. The results reveal that the anti-adhesive wear properties of the three TiAlN coated textured samples are significantly improved over that of the conventional one; the adhesion of TiAlN coatings is greatly improved by using Nd:YAG laser substrate pretreatment. Moreover, laser-scanning speed has a profound effect on the adhesion strength of the pretreated samples. In the experiments, the lowest scanning speed (5mm/s) is most effective in providing a greater mechanical locking of the coatings upon the substrate and a more matching chemical property between substrate and coating materials, thus increasing the critical load of the coatings. Meanwhile, the adhered workpiece material layer is more stable on the pretreated sample irradiated at 5mm/s. Hence, potential wear protecting properties of the in-situ formed layer can be conserved.