Investigation of the tribological properties of Ti-TiN-(Ti,Al,Nb,Zr)N composite coating and its efficiency in increasing wear resistance of metal cutting tools

Abstract

The paper offers the findings of the investigation focused on the tribological properties of a sample with the Ti-TiN-(Ti,Al,Nb,Zr)N coating depending on temperature, which varied in the range of 500–1000 °C. It is found that as the temperature rises to 700 °C and higher, the adhesion component fadh of the coefficient of friction (COF) measured for a coated sample becomes significantly lower (by about 20%) as compared to the value of fadh for an uncoated sample. The paper also describes the results of the studies of the wear pattern on a metal-cutting tool depending on the cutting speed (vc = 300 and 400 m/min). With an increase in the cutting speed from 300 to 400 m/min, the depth of diffusion of iron (Fe) into the coating increases by 56%, while the depth of diffusion of titanium (Ti) and other coating elements into the material being machined increases by 35%. With an increase in the cutting speed, the value of the adhesion component fadh of the COF slightly decreases and, accordingly, the value of the adhesion component of the tool wear mechanism declines. At the same time, the diffusion mechanisms become more active, and the direct temperature effect on the coating increases, which provokes the formation of internal transverse cracks and delaminations.