Effect of Nitrogen Contents on Mechanical and Titanium Alloy Cutting Performance of (TiAlTaCrZr)N Coatings by DC Magnetron Sputtering

In order to solve the problem of poor thermal conductivity of traditional tool coatings with high wear resistance, the coatings of (TiAlTaCrZr)N were prepared by DC magnetron sputtering under different nitrogen flow rates. The effects of different nitrogen contents on the microstructure, hardness, adhesion and thermal conductivity of the coatings were studied. With the increase in nitrogen flow rate, the content of N in the coatings increases, and the microstructure of the coatings changes from nanocrystalline to columnar crystal. The hardness of the coatings increases from 11.0 GPa of the TiAlTaCrZr coating to 20.6 GPa of the (TiAlTaCrZr)N coating with 5 mL/min nitrogen flow rate. The adhesion of the coating reaches to the value of 130 N when nitrogen flow is 5 mL/min, and then decreases gradually with the increase in nitrogen content. The thermal conductivity of the (TiAlTaCrZr)N coating is better than that of the TiAlN coating, but it decreases with the increase in nitrogen content. Since the (TiAlTaCrZr)N coating has high thermal conductivity, high adhesion and high hardness, the cutting length of the (TiAlTaCrZr)N coating is 175% higher than that of the TiAlN coating for the titanium alloy cutting. It provides a new tool coating with high wear resistance and high thermal conductivity for titanium alloy cutting.