EFFECTS OF BIAS VOLTAGES ON ADHESION AND PROPERTIES OF CHROMIUM NITRIDE THIN FILMS

Thin films were deposited on SUS440 stainless steel samples by arc plasma evaporation at substrate bias voltages of 10–100 V. X-ray diffraction, optical microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, microhardness test, and electrochemical test were used to investigate the morphology and properties of the thin films. Particularly, the thin films were composed of chromium nitride (CrN, phases of CrN + Cr) and 0.76 mm thick. They were deposited with microdroplets on the samples. The surface hardness of these films reached the highest value of 1492 HV at the bias of 20 V. As the bias voltage increased, the adhesion of the CrN thin films decreased. The excessively high bias voltage of 100 V led to the delamination of the CrN thin films. The electrochemical test demonstrated that the corrosion resistance in the 3% NaCl solution of CrN coating can be improved.