The anticorrosion and tribocorrosion properties of a multilayer diamond-like carbon (DLC) film were systematically investigated in NaCl solution. Electrochemical measurements suggest that the corrosion performance of the multilayer DLC film is superior to those of the substrate and single layer DLC film in NaCl solution, which is attributed to the successively multilayered structure with a well-bonded interface and the formation of Si oxides. An extremely high Warburg impedance value, higher than 10⁷ Ω cm², of the multilayer DLC film has been observed. Tribocorrosion tests show that the multilayer DLC film presents lower wear rate in NaCl solution, with the substrate and single layer DLC film as comparisons. We demonstrate that the multilayer DLC film is an excellent protective material for improving both corrosion and wear performance of the substrate.

Diamond-like carbon (DLC) and graphite-like carbon (GLC) coatings have good prospects for improving the surface properties of engine parts. However, further understanding is needed on the effect of working conditions on tribological behaviors. In this study, GLC and two types of DLC coatings were deposited on GCr15 substrate for investigation. The friction and wear properties of self-mated and steel-mated pairs were evaluated. Two temperatures (25 and 90 °C), three lubrication conditions (base oil, molybdenum dithiocarbamate (MoDTC)-containing oil, MoDTC+zinc dialkyldithiophosphate (ZDDP)-containing oil), and high Hertz contact stress (2.41 GPa) were applied in the experiments. The results showed that high temperature promoted the effect of ZDDP on steel-mated pairs, but increased wear under base oil lubrication. The increased wear for steel-mated pairs lubricated by MoDTC-containing oil was due to abrasive wear probably caused by MoO₃ and β-FeMoO_4. It was also found that in most cases, the tribological properties of self-mated pairs were better than those of steel-mated pairs.

In an effort to improve the surface properties of electrical contact materials in terms of high friction coefficient and wear rate, diamond-like carbon (DLC) films containing different metal elements were prepared on stainless steel substrates using an unbalanced magnetron sputtering system. In the present study, the effect of current-carrying on DLC film, Cu-doped DLC film (Cu/DLC), and Ti-doped DLC film (Ti/DLC) is reported. The structure and mechanical properties of the films were characterized systematically by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Raman spectra; these methods were also used to analyze the initial surface of the films. Moreover, the tribological behaviors of the films sliding against AISI 52100 steel with and without an electric current (1 A) applied were investigated using a tribometer with ball-on-disc configuration in an atmospheric environment. The results demonstrated that the friction coefficients of DLC and Cu/DLC under current-carrying condition were decreased, whereas Ti/DLC showed opposite experimental results. The wear rate of the films with a current was higher than that without a current. Therefore, this study is meaningful to understand the tribological behaviors of microelectromechanical systems.