Study on the properties of Cr/CrxN films prepared by magnetron sputtering and ion implantation alternately

Abstract

In this study, the efficacy of Cr/Cr_xN multilayer films, fabricated on 8Cr4Mo4V bearing steel substrates via Plasma-Based Ion Implantation and Deposition (PBIID) technique, was thoroughly examined. Utilizing a multifunctional coating apparatus, the surface engineering process was optimized for efficiency and precision, yielding controllable periodic Cr/Cr_xN films. Characterizations conducted with XPS, XRD, and TEM disclosed a 'stacked' stratified film structure that resonates with the process periodicity, characterized by a 17 nm cycle and consisting of dispersed nanocrystalline (Cr, CrN, and Cr₂N). These multilayer structures markedly enhanced the corrosion resistance of the material, with the treated 8Cr4Mo4V specimens demonstrating a corrosion current density of 2.47 × 10⁻⁷ A cm⁻², which is an order of magnitude reduction compared to the original sample of 7.60 × 10⁻⁶ A cm⁻². A series equivalent circuit model was developed to simulate the corrosion dynamics. The nitridation effect induced by ion implantation was instrumental in attaining a surface nanohardness of 19 GPa, approximately doubling the original hardness, while also achieving a coating-substrate adhesion force of 105 mN due to the peening effect. This method can be applied to improve the corrosion resistance life of precision parts, especially complex parts.