Study On The Transition Layer Structure Design And Mechanical Properties Of Diamond-like Films

A multitarget magnetron sputtering system was employed to depositcarbon-based thin films with different structures. The DLC films of differentstructure and function were prepared by elements doped buffer layer design, andmulti-functional gradient layer design, and investigated the performance of the DLCfilms in high temperature environment.Due to the deposition of C on Si target during the deposition process, we canuse this target poisoning phenomenon to deposit DLC film with trace or low Si, theSi-DLC films with different structures were prepared via different negative biasapplication. The structure, cross-sections, composition, mechanical and tribologicalproperties of the films was systemically investigated by XPS, Raman spectra,scanning electron microscopy, nano-indenter and tribo-tester. The results showedthat the content of sp³hybrid carbon was increased as the Si doped, and Si-dopingcould release the internal stress and increase adhesion to silicon substrate. TheSi-DLC film prepared at negative bias of-600V exhibited higher hardness, higheradhesion, respectively for13GPa and22GPa, lower friction coefficient about0.018and lower wear rate about1.60×10^-16m³/（N·m） in the ambient atmosphere.The tribological properties of Silicon containing diamond-like-carbon （Si-DLC）films, deposited by magnetron sputtering Si target in methane/argon atmosphere,were studied in comparison with diamond-like-carbon （DLC） films. The DLC filmsdisappeared due to the oxidation in the air at500℃after annealing while the Si-DLCfilms still remained, implying that the addition of Si improved significantly thethermal stability of DLC films, improves the sp³content of the film, effectivelysuppress graphitization of the films in high temperature environment. Retardedhydrogen release from DLC film at high temperature and silicon oxide on the surfacemight contributed to lower friction coefficient of the Si-DLC films both afterannealing treatment and in situ high temperature environment.Using Ti target by introducing components gradient transition layer, the DLCfilms with titanium transitional layer were obtained. Testing show that the DLCfilms with Ti transitional layer and TiC gradient layer had an excellent combinationof power, to reach55N, and low friction coefficient, compared to304stainless steelsubstrate by deposition of DLC and contains only Ti transitional layer DLC films, itimprove filmcombination of strength, lower coefficient of friction of the film, andincrease the wear resistance of the film.