Preparation Of Nano Structured Diamond Like Carbon Films And Its Tribology Performance

Based on plasma enhanced chemical vapor deposition (PECVD), using high power pulse technology, constant current high frequency dual-pulsed technique and liquid carbon source prepare carbon films. Through the adjustment of the growth parameters, the influence of various process parameters on the film nano structure and performance were studied. And the influence of the film nano structure on its mechanical、tribology and surface properties were discussed. The structure evolutions of special nanometer structures in the process of friction were investigated. The main contents of the thesis include:1. Fingerprint carbon films were prepared by a high power pulsed plasma chemical vapor deposition technique. These particular structures in the films were verified by HRTEM and Raman spectra. The fingerprint-like carbon films show excellent mechanical properties, i.e. high hardness (21.5GPa) and high elasticity (elastic recovery of85%). More importantly, the films exhibit ultra-low friction coefficients (-0.009) under ambient conditions with35%relative humidity. HRTEM images demonstrated that the fingerprint-like nanostructures were preserved in the wear debris, which considered being the major cause for ultra-low friction.2. Carbon onions/amorphous carbon films were grown by constant current high frequency dual-pulsed plasma enhanced chemical vapor deposition technique. Thanks to the unique carbon onions both in bulk and debris of amorphous carbon matrix, the films show not only a super high elastic recovery up to92%, but also a super-low friction coefficient (μ<0.008) and wear rate (6.41x10-18m3/Nm) in ambient atmosphere (30%relative humidity). The participation of carbon onions during the friction process can be explained as "molecular bearing", which converts the sliding behavior into rolling behavior, resulted in both super low friction and wear rate.3. Fullerene/amorphous nanostructured carbon films were synthesized using plasma enhanced chemical vapor deposition technique on silicon (100)-substrate using cyclopentadiene as carbon source. The microstructure of the films was characterized by high resolution transmission electron microscopy (HRTEM) and Raman spectra. The images showed the presence of multilayer curved fullerene-like arrangements embedded in an amorphous body. Thanks to the novel nanostructure, the films show excellent mechanical and tribological properties.4. The friction and wear properties of fullerene like carbon films using ionic liquids as lubricants were studied. The results showed that the hydrogen type of fullerene carbon film show the anti-friction performance on low frequency friction; In the high frequency friction showed excellent anti-wear performance, wear life improved significantly. The boundary lubrication was considered to be the main reason for its anti-friction and anti-wear effect.