Properties and cutting performance of AlTiCrN/TiSiCN bilayer coatings deposited by cathodic-arc ion plating

This study was intended to investigate the properties and cutting performance of AlTiCrN/TiSiCN bilayer coatings. These coatings were deposited on cemented carbide substrate by the cathodic-arc ion plating method, using AlTiCr and TiSi alloy source. The properties of these coatings were investigated by nano-indentation, transmission electron microscopy (TEM), Electron Energy-Loss Spectroscopy (EELS) and pin-on-disc test. Nano-indentation hardness of AlTiCrN and TiSiCN were 41 GPa and 51 GPa, respectively. AlTiCrN layer was columnar structure and its size was less than 50 nm. Further more, the TiSiCN layer appeared to have nano crystalline structure and measured about 5 nm. In particular, TiSiCN film showed good tribological behavior and its friction coefficient measured 0.18 for the bearing steel counterparts (AISI 52100). AlTiCrN/TiSiCN bilayer coated carbide endmills were also evaluated in the machining of carbon steel (AISI 1049), hardened steel (AISI D2) and gray cast iron (AISI 35). These coated endmills showed better wear resistance than comparative TiAlN coated endmills. The tribological properties of TiSiCN layer decreased adhesion; however, the cutting performance of the mono layer TiSiCN coated endmill showed high compressive residual stress, which resulted in poor cutting performance. AlTiCrN/TiSiCN bilayer coatings showed exceptional cutting performance for all types of work materials.