Investigation of the nanostructure and post-coat thermal treatment of wear-resistant PVD CrTiCuBN coatings

Metallic nanocomposite coatings offer an enhanced hardness/elastic modulus (H/E) ratio, important for many wear applications. CrCuN coatings have shown promising impact wear properties and CrTiCuBN coatings are now being studied to investigate the effect of boron and titanium additions to this system. The coatings have been deposited by unbalanced reactive magnetron sputtering. The hardness, elastic modulus and nanowear properties of the coatings have been examined. For some compositions, post-coat vacuum annealing for up to 1 h at temperatures between 550 and 600 °C resulted in a significant increase in measured hardness. Characterisation of such films by X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) has been performed to provide information on chemical composition, nanostructure and bonding. The phase composition obtained is considered with reference to the Cr-B-N ternary phase diagram.