Study on the influence of substrate bias on the properties of CrAlN wear-resistant coating prepared by arc/magnetron composite technology

In this study, a combined deposition technique involving medium-frequency magnetron sputtering and arc ion plating was employed to deposit CrAlN coatings onto stainless steel substrates. Through comprehensive analysis using SEM, EDS, XRD, nanoindentation testing, scratch testing, and friction and wear testing methods, the influence of substrate bias voltage on the microstructural morphology, mechanical properties, and frictional characteristics of the CrAlN coatings was systematically investigated. With an increase in substrate bias voltage, the coating surface exhibited a morphological evolution from porous structures and large particles to a dense and smooth state. The coating prepared under a substrate bias of -30 V exhibited multiple strong diffraction peaks. Under a substrate bias of -60 V, the coating preferentially grew along the (200) crystal plane. Excessive substrate bias (-150 V) exacerbated the secondary sputtering effect during deposition, resulting in a decreased deposition rate accompanied by lattice relaxation and recrystallization. Furthermore, an increase in substrate bias initially enhanced the hardness and elastic modulus of the coating before subsequently decreasing them. Under a substrate bias of -60 V, the coating demonstrated lower wear rates, while higher biases transformed its wear mechanism into severe abrasive wear, leading to significant peeling off and exposure of the underlying material. By adjusting the substrate bias voltage, it is possible to effectively optimize the microstructure, mechanical properties, frictional behavior, and wear resistance of CrAlN coatings. Notably, CrAlN coatings prepared under a substrate bias of -60 V exhibited exceptional mechanical properties and wear resistance; thus providing crucial theoretical and experimental foundations for enhancing their performance in practical applications.