High temperature oxidation and cutting performance of AlCrN, TiVN and multilayered AlCrN/TiVN hard coatings

Abstract

Transition metal nitrides, such as AlCrN and TiVN, have been used as protective hard coatings due to their excellent tribological properties. In this study, nanostructured AlCrN/TiVN multilayered coatings were deposited periodically by cathodic-arc evaporation (CAE). During the coating process of AlCrN/TiVN, TiN was deposited as an interlayer to enhance adhesion strength between the coating and substrate. The cathode current of both AlCr and TiV alloy targets was controlled to produce hard nitride coatings. The multilayered AlCrN/TiVN coatings possessed higher hardness of 38GPa than that of the monolayered AlCrN (35GPa) and TiVN (22GPa) coatings. A ball-on-disc wear test at room temperature was conducted to evaluate the tribological properties and lubricities of the deposited coatings. It exhibited that the lowest wear rate was obtained for the AlCrN/TiVN coating, which was significantly lower than that of the monolayered AlCrN. To evaluate the cutting performance, end milling tests of 7000 series Al alloys of the deposited tools were conducted at high cutting speed. The multilayered AlCrN/TiVN coated end mills showed better tool life as compared to AlCrN because of high resistance to abrasive and adhesive wear. The design of multilayered AlCrN/TiVN hard coatings improves the overall tribological performance and applicability of these coatings in metal cutting by combining the abrasion-resistance and lubricating effect.