Microstructure and Tribological Properties of CrTiAlN Composite Coatings With Different Chemical Compositions Deposited by Multi-Arc-Ion Plating Technology

The CrTiAlN composite coatings with different chemical composition are deposited on the surface of 65 Mn steels by multi-ion plating technology in a gas mixture of Ar + N₂. The metallic ratio of Cr, Ti, and Al was varied by adjusting the currents of different TiAl targets. The coatings were characterized by means of energy dispersive X-ray analysis, X-ray diffractometry, scanning electron microscopy, microhardness tester, and ball-on-disk tribometer, respectively. The experimental results show that the surface morphology of CrAlTiN films is compact and dense. Moreover, the cross-sectional morphology appears as fibrous columnar structure. Compared with CrN coatings, the preferential growth orientation of CrAlTiN films was changed from CrN (111) to CrN (200) after the addition of Ti and Al elements. When the TiAl target arc current was 50 A, the hardness reached the maximum value of 35 GPa. The CrAlTiN composite films perform better than binary CrN as well as the Cr plating in terms of hardness and wear resistance at high temperature. Then, the tribological mechanism at high temperature for the aforementioned three kinds of coatings was discussed.