Properties of single layer and gradient (Ti,Al)N coatings

This paper discusses the deposition parameters and the properties of cathodic arc deposited single layer and gradient (Ti,Al)N coatings using TiAl cathodes. We noted that the bias voltage had a significant influence on the formation of macro droplets and the number of macro droplets decreased with increasing bias voltage. The hardness decreased with increase of bias voltage from −75 to −300 V and a maximum hardness of 2783±25 HV was achieved at −75 V and at a N2 pressure of 0.66 Pa. The adhesion strengths of (Ti,Al)N coatings deposited on M2 steels were in the range of 44–92 N (Lc1). A high adhesion strength of 92 N (Lc1) was observed for a coating deposited at −75 V and at 1.33 Pa of N2. Gradient coatings deposited by continuously varying the bias voltage during the deposition of coatings exhibited higher values of critical loads of adhesion (Lc1 in the range of 87–97 N and Lc2>120 N) for both positive and negative gradient coatings. The higher critical loads of adhesion observed for gradient (Ti,Al)N coatings suggest that there is an excellent potential to further enhance the wear properties of (Ti,Al)N coatings.