Composition, Structure and Properties of CrAlN-DLC Hard Composite Films Deposited by Arc Ion Plating

To improve the friction performance of CrAlN film, CrAlN-DLC hard composite films with different compositions were prepared on the cemented carbide substrates using separation target arc current control technology of the enhanced magnetic filter pulsed bias arc ion plating equipment, and their surface morphology, composition, phase structure, mechanical, and friction properties were investigated. The results revealed that the surfaces of different films were flat and dense, and the film thicknesses were all about 1.05 mu m. With the increase of target arc current ratio (I-C/I-CrAl), the carbon atomic content of the film increased from 33.1% to 74.6%. Phase structure of the film was mainly composed of crystal phase and amorphous phase. With the increase of carbon content, the crystal phase of c-(Cr,Al)N decreased and the crystal grain size reduced, besides, the ratio of sp(2)/sp(3) in DLC amorphous phase decreased. Correspondingly, the hardness of the film increased with the increase of carbon content. When the carbon atomic content is 74.6%, the hardness reaches the maximum of (26.2 +/- 1.4) GPa, which results in the friction coefficient at this point attaining the minimum value of 0.107, and the wear rate is only 3.3x10(-9) mm(3)/Nm. In summary, the comprehensive performance of the CrAlN-DLC composite film reaches the best when the content of amorphous DLC phase get the maxium, and the friction performance is significantly improved as compared to the CrAlN film.