Improved interfacial adhesion of AlTiN coating by micro-grooves using ultrasonic surface rolling processing

Abstract

The micro-textures fabricated on the substrate surface of coating are a feasible method to improve the interfacial adhesion of the coating. This research proposes an ultrasonic rolling texturing method, and for the first time reveals how different ultrasonic rolling texturing process parameters (including air pressure, step distance, and feed speed) impact the bonding properties of AlTiN coating. The texture profile, surface morphology, hardness, elasticity modulus, and surface stress state are investigated. Then, the scratch tests are implemented to study the adhesion properties of these textured AlTiN coatings. Results showed that periodic micro-grooves were controllably fabricated, accompanied by high compressive stress and increased surface energy on AISI 5140 steel surface by ultrasonic rolling texturing. The surface morphologies and mechanical properties of the textured surface were strongly dependent on the texturing parameters. And the ultrasonic rolling textured substrate was conducive to the coatings in terms of interfacial contact area, wettability, surface energy, hardness, and residual stress, which could enhance the interfacial adhesion of the coating-substrate. The critical failure loading force of all textured coatings ( F N = 43–59.35 N) exhibited higher value in comparison with the polished coating ( F N = 37.91 N), demonstrating that ultrasonic rolling texturing presented a great potential in the fabrication of high precision micro-textures for enhancing the interfacial bonding properties of coatings. Furthermore, the enhancement mechanism for the ultrasonic rolling texturing on the AlTiN coating adhesion was discussed. The developed texturing method supports the application of hard coatings on mechanical parts such as molds, bearings, etc. • USRP texturing method was proposed and verified. • The coating interfacial adhesion can enhance by USRP texturing pre-treatment. • The USRP texturing parameters had an impact on the coating adhesion behavior. • The enhancement can be attributed to the synergy of hardening and micro-grooves.