The influence of temperature on the microstructure and mechanical properties of sputtered Cr2Nx coatings

Hard ceramic coatings of Cr2Nx, made by magnetron sputtering, were heat treated in vacuum in the temperature interval from 200 to 700°C, and the development of the microstructure was studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The room-temperature hardness of the annealed coatings was measured by nanoindentation, and the chemical composition was measured by energy recoil detection analysis. Due to the heat treatment, the oxygen content of the coatings increased while the nitrogen content decreased slightly. In addition, grain growth and lowering of the microstrain were observed, which did not result in a decrease in hardness. On the contrary, an increase in hardness was observed.