Influence of transition metal doping on the tribological properties of pulsed laser deposited DLC films

摘要

Doped or alloyed diamond-like carbon (DLC) films exhibit superior properties compared to undoped DLC films. But the choice of dopant plays a vital role in tailoring specific properties of the DLC film desired for specific application. In the present work, a comparative study has been carried out in order to bring out the effect of transition metal (TM) doped DLC film on the tribological properties. Nanocomposite DLC/TM (TM=Ag, Ti and Ni) films were deposited by nanosecond pulsed laser deposition (PLD) technique on to AISISS304 substrates. Films microstructure and chemical behavior was studied by glancing incidence X-ray diffraction (GI-XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and high resolution transmission electron microscopy (HRTEM). The sp(2) and sp(3) fraction in the films are well described by electron energy loss spectroscopy (EELS) analysis. The Raman spectra of DLC/TM films showed peak shift towards lower wavenumber indicating the reduction of internal compressive stress. Formation of TM nanoclusters and TiC phases were confirmed in DLC/TM films by GI-XRD, XPS and HRTEM. DLC film doped with nanocrystalline Ag showed low friction behavior due to the formation of large amount of sp(2) lubricant phase. However, high friction coefficient measured in DLC film doped with Ni and Ti. Such a high friction is explained by the presence of hard TiC and sp(3) phase in the DLC/Ti and DLC/Ni films respectively. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.