Dependence of microstructure and hardness of TiAlN/VN hard coatings on the type of substrate rotation

In industrial PVD deposition systems the substrates usually move in a so-called planetary rotation in order to deposit a homogeneous coating on the whole surface area of the tools. In this study we compared microstructure, surface topography and hardness of the coatings, deposited in the same batch but using different types of rotation: one-fold, two-fold and three-fold. The coating was a multilayer TiAlN/VN, deposited by magnetron sputtering. Microstructure was studied on cross-sectioned samples using SEM, prepared either by fracture or by focused ion beam. Coatings prepared by two-fold and three-fold rotation were very similar, both in microstructure and in hardness. They had dense, only slightly columnar microstructure. In contrast, coatings prepared by single rotation had a pronounced columnar microstructure, and substantially lower hardness.

► TiAlN/VN hard coatings were deposited using one-, two- and three-fold rotation. ► Microstructure extends from strong columnar in one-fold to dense in three-fold rotation. ► Hardness is comparable in two- and three-fold rotation, but much lower in one-fold. ► Deformation during indentation is achieved by shearing of individual columns.