Effects of Tantalum Doping on Friction and Corrosion Behavior of Multilayer Ta-DLC Films
Diamond-like carbon (DLC) films are widely applied in material protection due to high hardness, excellent wear resistance, and corrosion resistance. To solve the problem that 316L stainless steel is prone to wear and corrosion in the environment of marine friction and corrosion, Ta/TaN/TaCN/Ta-DLC films were deposited on 316L stainless steel by mid-frequency magnetron sputtering technology. The surface morphology, cross-sectional morphology, and corrosion morphology of the prepared films were observed by scanning electron microscopy (SEM). Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffractometer (XRD) were used to analyze the electronic structure of carbon element, chemical bond information, and phase composition in DLC films, respectively. The tribological and mechanical properties were tested by scratch method, nanoindentation test, and friction and wear test. The corrosion resistance of the films was tested by the electrochemical method. The effect of Ta element content in DLC film on the structure, composition, mechanical properties, tribological properties and corrosion resistance of the film was studied.The results showed that all films had a smooth surface and small surface cluster particles. When the doping content of Ta element was 2.04at.％, there were defects on the surface of the film. With the content of Ta element increased from 2.04at.％ to 4.16at.％, the sp3 carbon in the film showed a trend of firstly increasing and then decreasing. The content of sp3 carbon in the film was the highest when the Ta content was 3.60at.％. The Ta element was mainly present in the forms of TaO and TaC in the surface DLC layer. Ta doping had little effect on film adhesion, and the adhesion of all films was about 10 N. When the Ta element doping content was 2.04at.％, the adhesion decreased slightly due to obvious defects in the film. With the increase of the doping content of Ta element in the Ta-DLC layer, the nano-hardness and elastic modulus of the films showed a trend of firstly increasing and then decreasing, which was consistent with the changing trend of sp3 carbon content in the Ta-DLC film, indicating that the change of carbon electronic structure in the Ta-DLC film layer played a major role in the nano-hardness of the film. The average friction coefficient of 316L stainless steel was 0.87, and the friction coefficient of the prepared film was generally between 0.21-0.43. Under the action of low load, the film had a good protective effect on 316L stainless steel. In addition, with the increase of the Ta element content, the average friction coefficient of the films gradually decreased, reaching a minimum of 0.21 at 4.16at.％. When the Ta element content was 3.60at.％, the corrosion current density and passivation current density of the film were 0.006 μA/cm2 and 0.63 μA/cm2, respectively, which were 1 to 2 orders of magnitude lower than other films, and its film resistance and charge transfer resistance were the largest, showing the most excellent corrosion resistance. In short, the doping of the Ta element improves the friction resistance of Ta/TaN/TaCN/Ta-DLC film, and the appropriate doping amount of the Ta element can improve the wear resistance and corrosion resistance of Ta/TaN/TaCN/Ta-DLC film.
DLC filmmagnetron sputteringcorrosionfriction and wearelement doping
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