A comparative study on Ti1 − xAlxN coatings reactively sputtered from compound and from mosaic targets

The aim of this work is to illuminate the influence of two widely applied target types, i.e. TiAl compound targets produced by powder metallurgy and mosaic TiAl targets, on the sputter deposition process as well as on the structure and properties of the obtained coatings. After development of a sputter process for the compound targets by optimization of cathode power and nitrogen partial pressure, this process was compared to the commercially applied mosaic target process by taking into account the sputter yields of Ti and Al and the respective deposition rates. The deposition rate achieved with the compound targets was ~ 44% higher than that obtained for the mosaic targets. The Al content in the coatings deposited from the compound targets was slightly higher and the domain size of the formed cubic Ti1 − xAlxN solid solution considerably larger than for the coatings deposited from the mosaic targets. The coatings grown from the compound targets showed, in contrast to those synthesized from the mosaic targets, tensile stresses. While the hardness of the coatings sputtered from the compound targets was slightly below that of the coatings synthesized from the mosaic targets, both their friction and wear behavior were slightly improved. In summary, it could be shown that using compound TiAl targets manufactured by powder metallurgy, Ti1 − xAlxN coatings with mechanical and tribological properties comparable to those grown from commercially applied mosaic targets can be deposited at significantly higher growth rates.