Preparation and properties of TiAlN coatings on silicon nitride ceramic cutting tools

In this study, a PVD-based multi-arc ion plating technique was employed to prepare TiAlN coatings on the surface of commercial silicon nitride cutting tools. The effects of different bias voltages on the microstructure, mechanical properties, cutting performance, and wear mechanisms of the TiAlN-coated silicon nitride cutting tools were investigated. Increasing the negative bias voltage gradually decreased the number of large particles on the surface of the TiAlN coating and improved its structure. The coating thickness increased with increasing bias voltage up to a maximum value and then decreased. The hardness of the TiAlN-coated silicon nitride ceramic cutting tools increased monotonously from 2260 +/- 50 to 2681 +/- 75 HV0.05 with increasing bias voltage. The adhesive force between the coating and the substrate also increased initially with increasing bias voltage before decreasing. The sample prepared at a bias voltage of -100 V resulted in a maximum adhesive force of 63 N and showed the best cutting performance of all tools prepared in this work, with a cutting length of 1500 m. Different wear mechanisms were observed for cutting tools prepared at different bias voltages; abrasive wear was dominant for samples prepared at -50 V, while both adhesive and abrasive wear were observed for the three tools prepared using bias voltages between -100 V and -200 V.