Adhesion strength of DLC films on glass with mixing layer prepared by IBAD

The improvement of the adhesion of diamond-like carbon (DLC) films has been tried by ion beam assisted deposition (IBAD). The adhesion strength must be quantitatively evaluated and determined in order to confirm the improving effect of the adhesion of DLC films by IBAD. In this study, DLC films were prepared on a glass substrate with a mixing layer prepared by IBAD. For the samples, the scratch tests were carried out using a scratch tester with a CCD camera and two AE sensors. The detachment process of the DLC film during a scratch test was observed and the detachment area was measured. On the other hand, AE signals were detected corresponding to the detachment of the DLC film, and the force causing the detachment was determined by analyzing the signals. The adhesion strength of DLC films was calculated from the detachment area and the force. From that result, the adhesion strength of DLC films without a mixing layer was 3.2 MPa. When the mixing layer was formed by IBAD with a condition of Ar-30 kV and 2.1 μA/cm2, the adhesion strength increased to 10.7 MPa. Furthermore, that increased up to 44 MPa in the case of 21.0 μA/cm2. Therefore, it was realized that IBAD improved the adhesion of DLC films and the effects were made clear quantitatively.