CHARACTERIZATION OF THE MECHANICAL-PROPERTIES OF CARBON METAL MULTILAYERED FILMS

Hard amorphous carbon films exhibit excellent wear resistance and low friction. The hard carbon films are brittle and have a high internal s tress. Also the abrupt change of elastic modulus at the interface of t he film and metallic substrate results in low adhesion and reduces loa d carrying capacity. Composite film structures with alternating layers of hard carbon and metallic films has been shown to possess unique me chanical properties such as enhanced fracture toughness and high hardn ess. Elastic mismatch may also be avoided by careful control of compos ition. The stress relaxation, when possible, enables the growth of thi cker films. Multilayer films with alternating layers of hard carbon an d TINx have been deposited by using an are discharge deposition appara tus. The carbon plasma is generated with a pulsed plasma source. The t itanium and TiN films are deposited by using a d.c. are source equippe d with a particle filtering. Films with a thickness of about 0.5 mu m were deposited with 10 layers of carbon and TiNx. The substrate materi als were AISI440B stainless steel and (100) silicon. The film composit ion was determined by nuclear resonance analysis, Rutherford backscatt ering, scanning electron microscopy and scanning force microscopy. The wear resistance and load carrying capacity was tested by using a pin- on-disc test. The friction coefficient of the multilayer films was obs erved to be lower than for the pure diamond-like carbon films, while t he wear rate of the multilayer film slightly increased and the wear ra te of the counter surface was increased about ten fold.