Improved tribological properties of TiC with porous nanostructured TiO ₂ intermediate layer

The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO2 coating is deposited as an intermediate layer on hot-work steel (H11) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO2 interlayer improves the friction, wear, hardness, and elastic modulus of the system. © 2011 Elsevier B.V. All rights reserved.