Preparation Of Si，Ni，Ti Doped Diamond-like Carbon Films And Investigation Of Their Tribological Behavior

Amorphous diamond-like carbon films were deposited on silicon （100） substrates at relatively lowvoltage （150V） and low temperature （60-70℃）, using a direct current pulsed power supply, withdimethylsulfoxide as carbon source and surface-modified nanoparticles as the dopant. The morphology ofthe composite films was analyzed by scanning electron microscopy （SEM） and atomic forcemicroscopy（AFM）．The microstructure of the composite films was analyzed by transmission electronmicroscopy（TEM）, X-ray photoelectron spectroscopy （XPS），and Raman spectroscopy．The wear behaviorof the composite films were examined on the UMT test system.（1） Synthesis of nanosilica doped diamond-1ike carbon composite films by electrochemical methodDiamond-like carbon films doped with surface-capped nanosilica （nano-SiO₂/DLC） were prepared on Sisubstrate via electrochemical deposition of dimethyl sulfoxide （DMSO） as the carbon source and nanosilicaas the dopant, at150V and70℃. It has been found that silica nanoparticles are well embedded inamorphous carbon matrix forming nanosilica-doped DLC composite films, confirmed by transmissionelectron microscopy （TEM）. In particular, Raman and atomic force microscopy analysis revealed theas-obtained composite films consist of both tetrahedral （sp3） and trigonal （sp2） bonded C species, and silicaincorporation results in variation of surface roughness, decrease of sp3-hybridized carbon concentrationand enhancement of graphitization. Furthermore, nanosilica surface-capped with organic compoundcontaining hydroxyl group is doped in amorphous carbon film by forming Si\O bond, which helps to lowerthe surface energy and induce hydrophilic to hydrophobic transformation of the carbon films. Tribologytests also showed that composite films have better friction and wear behaviors, compared with pure carbonfilm.（2） Synthesis of nanonickel doped diamond-1ike carbon composite films by electrochemical methodWe choose dimethyl sulfoxide （DMSO） as the carbon source and surface-capped Ni nanoparticle as thedopant, to fabricate doped diamond-like carbon films on Si substrate via electrochemical deposition, at150V and60℃. Undoped DLC films were also prepared at various deposition durations for comparativestudies. route．The transmission electron microscopy and X-ray photoelectron spectroscopy results showthat zero-valence silver nanoparticles are stable and well dispersed in the amorphous carbon matrix withunchanged size. size．And the incorporation of surface modified Ni nanoparticles in the carbon matrixcaused a higher content of sp2carbon than the undoped DLC film. spectroscopy. Fourier transforminfrared、spectroscopy showed that the deposits were typical hydrogenated DLC films. Tribology testsalso showed that incorporation of Ni nanoparticle led to better friction and wear behaviors, compared withpure carbon film.（3） Synthesis of TiO₂doped diamond-1ike carbon composite films by electrochemical methodDiamond-like carbon films doped with surface-capped TiO₂were prepared on Si substrate via electrochemical deposition of dimethyl sulfoxide （DMSO）, at150V and70℃. The morphology,composition， and microstructure of the film were investigated by means of X-ray photoelectronspectroscopy， Raman scattering spectroscopy and transmission electron microscopy． Moreover,thetribology behaviors of the TiO₂-doped DLC films were also investigated in our work．The results show thatTiO₂nanoparticles are stable and well-dispersed in the composote films, and the incorporation of TiO₂nanoparticles in the carbon matrix caused a higher content of sp2carbon than the undoped DLC film. Thecomposite films also maintained better wear behaviors than pure DLC films.