Characterization and Mechanical Properties of Ti-Al-Cr-N Nanocomposite Coatings Deposited by Closed Field Unbalanced Middle Frequency Magnetron Sputtering

Ti-Al-Cr-N coatings, characterized by a nanocomposite comprising nano-sized TiN crystallites embedded in amorphous AlN or CrN matrix, could be successfully synthesized on Si(111) and WC-Co cemented carbide substrates by a closed field unbalanced middle frequency magnetron sputtering method. The Cr content in the Ti-Al-Cr-N coatings linearly increased from 11.2 to 32.8 at.% raising the Cr targets currents from 5 to 15 A, whereas the Ti content decreased from 63 to 47 at. %. The high resolution transmission electron microscope (HRTEM) image and diffraction patterns clearly show that the Ti-Al-Cr-N coatings were composites of crystallites and amorphous phase, which were distinguished from each other by lattice fringe contrast. The hardness and Young's modulus value of the Ti-Al-Cr-N coatings increased with incorporation of Cr, and had the maximum value of 38.9 and 475 GPa at the Cr content of 17 at. %, respectively. The average friction coefficient of the Ti-Al-Cr-N coatings largely decreased with an increase of the Cr content when compared to the TiN coatings. (C) 2011 The Japan Society of Applied Physics