Microstructure and Tribological Properties of Thick (Ti, Cr, V) N Nanocomposite Coatings at a Wide Temperature Range

Abstract

The effects of service environment temperature (25, 550, 650, 700, and 750 °C) on the friction and wear properties of (Ti, Cr, V) N composite coatings were investigated. The structure and phase of the coating before and after wear at wide temperature ranges were analyzed by scanning electron microscopy, XRD, transmission electron microscopy, and Raman spectroscopy. A wide temperature range wear test was carried out at room temperature, 550, 650, 700, and 750 °C for 20 min using a reciprocating friction and wear tester. The results show that the (Ti, Cr, V) N composite coating overcomes the shortcomings of single nitride, which is the initial oxidation temperature is low in a wide temperature range. The surface oxides produced at 25-750 °C have an important influence on the wear behavior and wear resistance. At room temperature and 550 °C, the main phase of the coating is the TiCrVN hard phase, which can reduce the wear rate of the coating at room temperature. At higher temperatures of 700 and 750 °C, dense oxide hard films of Cr₂O3, TiO₂, V₂O₅, and TiVO₄ formed on the wear scar surface play a key role during friction and wear. 650 °C is a critical temperature for wear behavior change. The mechanical properties of the coatings at 700 and 750 °C are significantly higher than those at 650 °C, and H_IT³/E^*2 is increased by 76%, which improves the wear resistance and reduces the wear rate. The coating is mainly oxidative wear at high temperatures above 700 °C. It is shown that the wear resistance and oxidation resistance of the composite coating can be improved by the mutual doping of Ti, Cr, and V elements in a wide temperature range.