Enhancing adhesion strength of PVD AlCrN coating by novel volcano-shaped micro-textures: Experimental study and mechanism insight

The adhesion strength of coating is critical to the coating lifetime. Our previous study found a novel volcano-shaped texture enhanced the adhesion of physical vapor deposition (PVD) AlCrN coating. This study aims to further investigate the influence mechanism of this texture. Volcano-shaped textures with different diameters and area ratios were fabricated on DC53 die steel samples by a long-pulse-width laser. By adapting X-ray diffraction (XRD), curvature measurement and cross-sectional observation of textures, chemical compliance of coating and substrates, stress condition of the substrate surfaces and physical bonding of coating and substrates were analyzed. Scratching tests and indentation tests were also conducted to study the adhesion strength under dynamic and static contact. The results showed that textured surfaces boasted better chemical compliance with coating than the untextured one; textures with suitable topographic parameters could reduce inner defects of coating and curb crack propagation, thus inhibiting coating spallation. The most suitable topographic parameters were found to be a diameter of 310 μm and an area ratio of 25 %, of which the critical load of coating failure (Lc) has improved 17.5 % from that of the untextured sample. This study will provide guide for design and optimization of surface topography of textured coating.