Crystal structure and friction and wear properties of cu films deposited at low temperatures by ion plating

Cu films were deposited on carbon steel substrates at low temperatures (LT, 164 K-115 K) and room temperature (RT) by ion plating. The crystal structure and morphology of the Cu films were analyzed by X-ray diffraction and scanning electron microscopy. The friction and wear properties were tested by home-made ball-on-disk vacuum tribometer. The adhesive critical load (L_c) between Cu film and substrate was also measured by scratch tester. The results show that substrate temperature significantly affected the preferred orientation of ion-plated Cu films. At -600 bias voltages, the LT Cu films showed (111) preferred orientation, while the RT Cu films showed (200) preferred orientation. In compared with the RT Cu films, the LT Cu films exhibited smoother surface morphology and better adhesion between the film and substrate. Wear rates of the LT Cu films were significantly lower than that of the RT Cu films in vacuum. The friction and wear properties were discussed in terms of structure and mechanical properties of the Cu films.