PVD coatings are gradually replacing the traditional methods based on electrolytic deposition. In this context an important role is represented by nanostructured coatings, in which the film is formed by a biphasic system with a microstructure designed to prevent formation, movement and growth of dislocations and microfractures. Thanks to biphasic system, formed by nanocrystals of a hard material with particles of ca.10 nm embedded in the matrix, a nanocomposite material with a hardness 4-6 times higher of starting materials is obtained. For this reason these coatings can be considered in cutting operations of difficult to cut materials.
Based on the satisfactory results achieved by previous work, two different kinds of AlSiTiN coatings,, multilayer and gradient were prepared using cathodic arc deposition. The nanostructured coatings were deposited on a WC-Co substrate, chosen because of the proper hardness and toughness for the considered application field. The coatings showed good adhesion to the substrate and high hardness. Wear tests at high temperature indicated a greater resistance than traditional coatings. These results were confirmed by milling tests of dye steels in dry conditions.
The overall analysis allows to define cutting operations with high thermal solicitations as potential application field for AlSiTiN.