Low-stress optimization and enhanced tribological properties of multilayer DLC films via alternating-energy deposition

Abstract

Diamond-like carbon (DLC) films possess excellent mechanical and tribological properties, while their atomicscale residual stress regulation remains challenging for widespread applications. In this study, the effects of single-energy and alternating-energy deposition strategies on the growth, structural characteristics, and tribological properties of diamond-like carbon (DLC) films are investigated systematically using molecular dynamics simulations. Results reveal that the alternating-energy deposition strategy significantly reduces the residual stress of DLC film by optimizing the modulation ratio (lambda = 1.3) of film thickness at 1 eV/atom to that at 70 eV/ atom, achieving a maximal 85 % drop of residual stress, compared to that observed in single-energy deposition systems. This structural heterogeneity regulates local strain fields and disrupts continuous stress networks, effectively reducing overall residual stress. Tribologically, the alternating-energy system, particularly the softhard alternating configuration (1-70 eV), demonstrates lower friction coefficient than that in the hard-soft alternating case. This attributes to its periodic soft-hard alternating surface structure and the formation of a graphene-like layered architecture during the friction process, which minimizes the friction through weak van der Waals interactions and uniform stress distribution. These results highlight the potential of alternating-energy deposition for optimizing DLC film properties and provide theoretical foundation and experimental guidance for designing DLC films with low stress and high tribological performance.