Wear-corrosion behavior of ultra-thin diamond-like carbon nitride films on aluminum alloy

摘要

Diamond-like carbon films exhibit high hardness, high wear resistance and a low friction coefficient. They are extensively utilized in the mechanical, electronic and biomedical industries. This work evaluates the effect of the thickness of ultra-thin diamond-like carbon nitride films on their corrosion properties and their wear-corrosion resistance in a mixed 1 M NaCl+1 M H_2SO_4 solution using electrochemical methods. The corrosion current density and weight loss of all films during and after wear-corrosion test are also recorded. This work employs ion beam-assisted deposition (IB AD) to deposit DLC nitride films of various thicknesses (1.5,2.0,2.5 and 3.0 nm), containing 60 percent nitrogen gas in the form of a gaseous mixture of C_2H_2+60 percent N_2. The thickness of the films was measured using a transmission electron microscope (TEM). The atomic bonding structures of these DLC nitride films are analyzed using a Raman spectrometer and by electron spectroscopy for chemical analysis (RSCA). A scanning electron microscope (SEM) was adopted to elucidate the surface morphologies of the specimens after corrosion and wear-corrosion. The results indicated that all of the nitrogen-containing DLC films excellently protected the 5088 Al-Mg alloy substrate with an electroless plated Ni-P interlayer against corrosion, and that the degree of protection increases with the thickness of the film. In the wear-corrosion tests various potentials were applied during wear in the particular corrosive solution. The results further demonstrated that the wear-corrosion resistance of all the nitrogen-containing DLC films was as effective as corrosion protection, and that the wear-corrosion loss decreased as the film thickness increased.