High adhesion of diamond-like carbon thin film to an aluminum alloy achieved by substrate sputtering and redeposition method

A novel technique to improve the adhesion of a diamond-like carbon (DLC) film to an Al alloy was demonstrated in this study. DLC films were deposited by diode rf bias sputtering. The Al component in the substrate was initially deposited on a graphite target during the sputter-cleaning of the substrate. Then the graphite target and the deposited Al were simultaneously sputtered to form an interface layer between the DLC film and the substrate in the early stage of deposition. We call this method substrate sputtering and redeposition (SSRD), which enhanced the antiwear lifetime of DLC/Al alloy samples. X-ray photoelectron spectroscopy clarified that a thicker mixed layer of Al and C was formed around the interface in the case of a longer substrate sputtering duration in the SSRD method. This interface structure could account for the strong adhesion of the DLC film to the substrate and the reduced delamination of the film obtained using the SSRD method.