Adhesion and machining performance of PVD AlCrN coatings with an ion beam/laser textured substrate

Abstract

The insufficient adhesive strength of Physical Vapor Deposition (PVD) coatings is still the key issue that needs to be solved urgently for high-efficiency and high-quality difficult-to-machine materials cutting processing. Currently, laser micromachining is extensively utilized to fabricate micro-textures on the substrate to enhance coatings adhesion. However, laser ablation will cause irregular protrusions inside and on the edges of the textures, which could influence the quality of deposited coatings. Therefore, micro-textures were fabricated on the substrate by an ion beam (IBE)/laser machining method, and the influence of IBE/laser textures on the adhesive strength of PVD coatings is revealed. Firstly, a micro-pits array was prepared on WC/Co substrates with different machining parameters, such as laser repetition frequency and ion beam etching time. The micro-topography and mechanical properties of the substrates with different pretreatments were studied. Then, cathode arc-evaporation technique was utilized to deposit AlCrN film on the IBE/laser textured substrates. The scratch test and dry machining experiments of AISI 316 L stainless steel were performed to evaluate the adhesive strength and machining performance of the coated samples with various pretreated substrates. The results demonstrate that laser texturing and ion beam etching both enhanced the coatings adhesion. Therefore, the critical load of the coatings deposited on the IBE/laser textured substrates with 25 kHz laser repetition frequency and 150 min etching time (F N, C2 = 3.39 N) exhibited the highest value, which was 19.4% higher than that of the conventional AlCrN samples (F N, C2 = 2.84 N). Moreover, the cutting forces F X , F Y , F Z and the friction coefficient of IBE/laser textured coated tool were decreased by 18.7%, 20.6%, 10.2% and 16.7% compared with that of conventional coated tool at the high cutting speed of 200 m/min. Finally, the possible mechanisms of IBE/laser texturing pretreatment on enhancing PVD coatings adhesion were discussed. • A micro-pits array is fabricated by an ion beam (IBE)/laser machining method. • Effect of ion beam (IBE)/laser textures on adhesion of PVD coatings is studied. • Mechanism of IBE/laser texturing to improve coatings adhesion is revealed.