The effect of TiC transient layer on a DLC-based functionally gradient coating prepared by closed field unbalanced magnetron sputtering plating system

Recently, Diamond like carbon (DLC)-based functionally gradient coatings have been used in a variety of engineering applications as useful films with appropriate tribological properties verified in many tests. However, due to their inherent residual stresses, they have a tendency to peel off, thereby limiting their applications (involving high contact stresses) and deposition thickness. Their brittleness and low adhesion may stem from either a faulty layer design or the wrong choice of material and deposition method. Therefore, using both a suitable interleaving material and an appropriate deposition technology will create an inclusive vision to accommodate better film properties. In this study, Ti-a:C and Ti-TiC-a:C films on AISI M2 steel substrates were deposited by Closed Field Unbalanced Magnetron Sputtering (CFUBMS) method using pulsed-dc biasing, and the mechanical, the structural, and the tribological properties for both films were investigated. It was seen that the incorporation of a TiC buffer layer between the Ti interlayer and the a:C matrix played a positive role in terms of hardness, wear rate, and adhesion properties.