Tribological properties, oxidation resistance and turning performance of AlTiN/AlCrSiN multilayer coatings by arc ion plating

In this study, AlTiN and AlTiN/AlCrSiN coatings have been synthesized using arc ion plating for high-speed yet dry cutting applications. The effects of modulation period (from 17.8 to 4.2 nm) on microstructure, mechanical properties as well as high-temperature tribological and oxidation behavior of AlTiN/AlCrSiN multilayer coatings were investigated. AlTiN/AlCrSiN multilayer coatings exhibit a single-phase face-centered cubic structure with fine columnar grain morphologies. With the optimal modulation period of 8.3 nm, the multilayer coating can possess the highest hardness, the ratio of hardness to effective modulus and adhesion strength, thus exhibits the best wear resistance at elevated temperatures. Besides, the introduction of AlCrSiN sublayers significantly improves the oxidation resistance of AlTiN, which was oxidized entirely after heating up to 1000 °C in the air. Whereas, AlTiN/AlCrSiN multilayer coatings remain most of the nitride structure uninfluenced with a dense oxide scale (~0.3 μm thick) above. Comparing with AlTiN, the AlTiN/AlCrSiN (Λ = 8.3 nm) coated cemented carbide insert shows a notably longer lifetime during the process of high-speed yet dry machining SKD11, where the primary failure mode is the flank wear resulting from abrasive, adhesive and oxide wear.