Nowadays, most industrial tools and components are improved by means of various surface engineering operations such as Physical Vapor Deposition (PVD). In the recent years, applying multilayer nitride coatings have been developed among industrial applications such as cutting tools and forging mold and casting. In the current research, four multilayer TiN-TiCN-TiAlN coatings deposited on the surface of D3 tool steel by a cathodic arc vaporization system. Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM) were used to characterize the coatings. X-ray Diffraction technique was also used for phase identification. Evaluation of mechanical properties of the coatings was done using Nano-indentation test under 30 mN load. In order to investigate wear behavior of the applied coatings, ball-on-disk test with alumina balls under 5, 10, and 15 N loads within 1000 m distance was used. To identify dominant wear mechanism, wear path was analyzed by SEM and EDS. To investigate oxidation behavior and thermal stability of the coatings, heat treatment of the specimens in 400, 600, 800, and 1000 °C for 1 hour in a resistant furnace was performed. The obtained results show that existence of TiAlN increased surface roughness compared with TiN. According to Nano-indentation test results, coatings have hardness value of 2700 to 3400 HV. Four coatings also showed good resistance to plastic deformation. Results of the wear test showed that applying Ti-based coatings reduces friction coefficient. In addition, increasing applied load decreases both friction coefficient and weight loss of the specimens. The TiN-TiCN-TiN/TiAlN/TiN-TiCN-TiN coating exhibit the least friction coefficient (about 0.4) and wear rate in the average 10 N load. Furthermore, the wear rate of the substrate was 4 times greater than the mentioned sample. Abrasive wear and oxidation are the most dominant mechanisms of these coatings. Existence of TiAlN top layer increased oxidation resistance in the coatings and their working temperature. Keywords: Physical Vapor Deposition (PVD), multilayer coatings, Tribology, Wear, Oxidation
