Improvement of Adhesive Strength of Diamond Films by Plating Cr-diamond Composite Interlayer

The diamond films were fabricated by using a two-step process on copper substrates.Firstly,chromium(Cr)-diamond composite interlayer was electroplated on copper substrates,then continuous diamond films were deposited by using hot-filament chemical vapor deposition(HFCVD) method.The interfacial characteristics were investigated by indentation test.The film surface morphology,phase structure and inner stress were analyzed by scanning electron microscope(SEM),X-ray diffraction(XRD) and Raman spectrum.The results show that the diamond particles are deeply imbedded in chromium layer and the amorphous Cr in the composite interlayer is carborized to Cr3C2 in the CVD process.Low inner stress is detected in the diamond films and good adhesive strength between film and substrate is obtained due to the deep anchoring of the diamond particles in the Cr3C2 matrix.Concentric cracks but no delaminate area and radial cracks are observed on the periphery of the indentation in 294 N load indentation test.