Studies On The Preparation And Mechanical Properties Of Metal Composite Films Based Diamond-like Carbon

DLC is an amorphous carbon films containing diamond structure (sp3), which has many similar properties to diamond films. However, the practical applications of DLC films are still restricted by the high internal stress. Therefore, in this work, metal composite films based DLC were papared by the method of the introduction of metal-doped or buffer layer. The variation of the structure, morphology and mechanical properties of DLC films were investigated in detail.DLC films were prepared by pulsed cathodic arc evarportion. The results showed that the variation of pulse frequencies could significantly change the microstructure of DLC films, including the size and ordering of sp2 carbon clusters et al, resulting in the variation of the relative fraction of Csp3/Csp2. With the increase of the pulse frequency, surface roughness of the films decreased, and the hardness and internal stress increased. In addition, DLC films in the visible region had a relatively high transmittance and with the pulse frequency increaseing the transmittance of the films was significantly reduced.High content of Ti (or Cu) alloyed DLC films were deposited by dc magnetic separation and pulse cathodic arc plasma method. The results showed that Ti alloyed DLC films contained hard phase TiC. However, Cu atoms did not form chemical bonds with C atoms. Before annealing, the increasing metal content in the films, the hardness of Ti (or Cu) alloyed DLC films decreased, In addition, the stress of Ti doping DLC films basically unchanged, while the stress of Cu alloyed DLC films sharply declined. After annealing, internal stress of Ti (or Cu) alloyed DLC filmswas reduced more than 5 times.Nano-scaled Cr/DLC bilayer films with different relative thicknesses were prepared by double-excitation cathode arc evaporation. The results showed that the microstructure (size and ordering of sp2 clusters) changed with varying the thickness of Cr interlayer and DLC layer. When keeping the thickness of carbon layer 80 nm and the thickness of Cr interlayerwas 12~20 nm,the bilayer films possessed the highest content of sp3-hybridization carbonand microhardnesis. Internal stress of the bUayer decreased with the thickness of Cr interlayer increasing and did not change when the thickness exceeded 45 iim. When the thickness of the interlayer is 20 rnn and the thickness of the carbon layer is moK than 65~106 nm, Or interlayer did not effect the miaostructure of the Cr/DLC bilayer films. In addition,the introduction of Cr interlayer can reduce the friction coefficient and increase the transmittance in the visthle region of the films.