A composition spread approach to the optimization of (Ti,Al)N hard coatings deposited by DC and bipolar pulsed magnetron sputtering

Combinatorial synthesis and screening [Angew. Chem. Int. Ed. 38 (1999) 2494] is an established technique in pharmaceutical industry. Recently combinatorial approaches have been made to the screening of superconductive, magnetoresistant and photoluminescent materials ‘Chem. Int. Ed. 38 (1999) 2494’. Much less established is the composition spread approach for materials development [IBM J. Res. Develop. 13 (1969) 696; J. Mat. Sci. 5 (1970) 964]. This approach has recently been successfully applied to the development of dielectric materials [Nature 392 (1998) 162]. Although the development of multicomponent hard coatings by such an approach could lead to a significant decrease in cost and time, only little work has been done in this field up to now [Int. J. Inorg. Mater. (2001) in press]. In this paper, the deposition and characterization of laterally graded (Ti,Al)N hard coatings deposited by conventional DC and bipolar pulsed magnetron sputtering is presented. The coatings have been deposited by reactive magnetron sputtering, using an aluminum and a titanium target at a low angle to the substrate surface, as well as a system of apertures. The relation between composition and oxidation resistance of the ternary films has been investigated. The results illustrate that the combinatorial approach is a powerful and cost effective tool for the development and optimization of new materials for hard coatings.