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 simultaneously. 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.
Keywords
DLC, microscratching test, interfacial mechanics,
film-substrate system