Microstructural effect on the tribo-corrosion behaviors of magnetron sputtered CrSiN coatings

Abstract

Minimization of corrosion loss or corrosion-related loss is highly desirable for enhancing the tribo-corrosion resistance of physical vapor deposition (PVD) hard coatings. Various tribo-corrosion tests against Al2O3 counterparts combined with microscopic examinations, were used to study the tribo-corrosion behaviors of three typical kinds of magnetron sputtered CrSiN coatings. The dense and columnar coating exhibited superior tribo-corrosion resistance, with a lowest specific tribo-corrosion rate of 6 × 10−16 m3/N m and a lowest friction coefficient of ~0.14, where the dominant mechanism was considered as a layer-by-layer mechanical removal and the chemical corrosion was inappreciable. The porous and columnar coating failed for its poor intrinsic corrosion resistance. For the almost column-free coating, brittle fracture leaded to an increase of the corrosion component in the material wear, despite that the coating had the best intrinsic corrosion resistance. The comparison studies demonstrated that the dominant factors of the tribo-corrosion resistance are more complicated than purely mechanical wear or purely chemical corrosion; high compactness, effectively crack-controlled wear, and the dynamic equilibrium of depassivation-repassivation surfaces on the worn are indispensable for the highly tribo-corrosion resistant PVD hard coatings.