Effect of aluminum concentration on friction and wear properties of titanium aluminum nitride films

It is well known that the hard thin ceramic films are utilized to industrial applications such as cutting tools, molding dies and sliding parts, because of its effect of reducing the wear. Recently, the demand of TiAlN film is expanding, because it has a high oxidation resistance at elevated temperature as well as good wear resistance. In this paper, friction and wear properties of TiAlN films having various concentration ratios of Ti/Al have been studied. The films were deposited by a cathodic arc ion plating method on cemented carbide substrate with a thickness of approximately 3 μm. Composition of the deposited film was evaluated by energy dispersive X-ray spectroscopy. Crystal structure of the deposited film was characterized by X-ray diffraction. Hardness of the films was measured by a nano-indentation tester. Friction and wear tests were carried out by a pin-on-disk tribometer at 300, 473, 673 and 873 K. Compositions of the films deposited from cathode materials that have atomic ratios (Ti:Al) of 50:50, 34:66 and 25:75 in TiAl alloys were Ti0.6Al0.4N, Ti0.42Al0.58N and Ti0.3Al0.7N, respectively. The crystal structure of Ti0.6Al0.4N Ti0.42Al0.58N and Ti0.3Al0.7N were found to be a B1, B4+B1 and B4, respectively. Nano-hardness decreased with increasing Al content in the films. There is no correlation between friction coefficient of each film and test temperature. The width of wear track for each film decreased above the temperature of 673 K. Ti0.6Al0.4N film was worn less than the other films at 873 K.