Effect of Mo content on the structure and mechanical properties of TiAlMoN films deposited on WC-Co cemented carbide substrate by magnetron sputtering

TiAlMoN films with different Mo contents were deposited by magnetron sputtering at various duty ratios of sputtering Mo target power source, after depositing a Ti interlayer. The concentrations and structure of the films were determined by energy dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffraction. The Mo content of TiAlMoN films gradually increased with increasing the duty ratio. The structure of TiAlMoN films changed from blocky to featurelessness, and ultimately changed to columnar at 12.1 at.% Mo. The TiAlMoN films exhibited the single TiN-based phase with a TiN(111) preferred orientation, and the intensity of this diffraction peak gradually increased with increasing Mo content. Nanoindentation tests indicated that the hardness of TiAlMoN films continuously increased with Mo content, while the H/E ratio reached a peak at 8.3 at.% Mo. All the films exhibited a good adhesion to WC-Co substrates because of the internal Ti interlayer. The ball-on-disk wear properties of TiAlMoN films showed that the lowest wear rate and best wear resistance were for 8.3 at.% Mo, resulting from the formation of molybdenum trioxide on the surface of wear track.