Microstructural, mechanical and tribological performances of DLC/CrN multilayer films with different modulation period

Abstract

Multilayer structure design is an effective method to improve the mechanical and tribological properties of hard films. In this work, diamond-like carbon (DLC)/CrN multilayer composite films with varying modulation periods were successfully deposited on 35Cr2Ni4MoA steel and Si substrates using unbalanced magnetron sputtering, and the microstructure, mechanical and tribological performances of DLC/CrN multilayer composite films were analyzed detailedly. SEM and TEM characterization confirmed that the DLC/CrN multilayer composite films consist of alternating amorphous DLC layers and crystalline CrN layers. The intensity of the (111) diffraction peaks in DLC multilayer composite film exhibited a varying degree of reduction, and the 2θ positions of the (111) and (200) diffraction peaks showed a slight rightward shift. Raman analysis shown that the modulation period had a negligible impact on the sp³ hybridized carbon content of DLC/CrN multilayer composite films. Reduced residual stress and enhanced toughness by designing multilayer structural with modulation periods. As the modulation period decreased, the hardness and elastic modulus of DLC multilayer composite films increased. The tribological performances indicated that the primary wear mechanism between DLC/CrN multilayer composite films and Si₃N₄ ball in an atmospheric environment was abrasive wear, and film M2 exhibited the best tribological performance. Compared to single-layer DLC films, the residual stress of DLC/CrN multilayer composite films has been reduced by more than half, and the fracture toughness and wear rate have been significantly improved.