Effect of different Si content on tribocorrosion performance of CrN/CrSiN multilayer coatings

CrN/CrSiN multilayer coatings with different Si contents (Si-5, Si-10, Si-15) were fabricated by arc ion plating. The microstructure, mechanical properties, electrochemical performance and tribocorrosion behavior of the coatings were investigated systematically. The coatings were mainly composed of CrN phase. With increasing Si content, grain refinement and diffraction peak broadening of CrN were observed, while no significant changes in coating hardness or adhesion strength were detected. Electrochemical measurements revealed that the densification of the coatings was improved by Si doping, which consequently led to an increase in pore resistance (Rf) with higher Si content, while the charge transfer resistance (Rct) was reduced. The Si-15 coating exhibited the lowest Rct value of 1.08 × 104 Ω·cm2. Compared with the CrN coating, the tribocorrosion resistance was improved through the adoption of the Si doping multilayer structure. However, the performance was not linearly enhanced with increasing Si content. The Si-15 coating presented the highest tribocorrosion rate of 1.81 × 10–6 mm3/(N·m) among the CrN/CrSiN multilayer coatings. It was found that excessive Si content enlarged the potential difference between the coating and substrate, which exacerbated galvanic corrosion at the interface and consequently degraded the tribocorrosion performance. Finally, the tribocorrosion failure mechanism of the CrN/CrSiN coatings was discussed.