Analysis on the interfacial mechanics of microscratching test for DLC-G95CR18 film-substrate system

Diamond-like carbon (DLC) is one of the rising film materials in the aerospace, automobile and valve applications, for its inherent and unique properties in anti-wear and low friction. In this paper, an interfacial mechanics model of film-substrate system was established to evaluate the stresses and deformations at the interface of DLC-G95Cr18 film-substrate system accurately. A microscratching test was used to measure the load-carrying capacity of the DLC-bearing steel by ball on disc mode. The failure of this film-substrate system was determined using the acoustic emission and friction force signal simultane-ously. Then, the interfacial stresses and deformations were calculated by using the established model and the design algorithm. Both of the experimental and computational results showed that hard DLC film would experience a failure process of elastic-plastic deformation, which caused by the interfacial stresses and initial cracks. During the brittle fracture of DLC film, shear stresses were the main cause of the initial cracks. And the evolution of stress and deformation in the process of microscratching and the critical failure state under its critical load were analyzed. These result could be utilized in the analysis of the load-carrying capacity and the failure mechanism of DLC-G95Cr18 film-substrate system.