Development of an Environmentally Conscious Carbon Thin Films

Abstract

  A diamond-like carbon (DLC) film is characterized by its high hardness and low friction coefficient. These properties have quickly promoted their wide use in consumer products, such as tools, sliding components like dies, razor blades, and PET bottles. However, a DLC film has insufficient hardness. This has prevented its application to cutting tools for aluminum alloys of emerging demand. Therefore, this study addresses novel hard nanocarbon films, including high-density DLC films, nano-diamond films, and hybrid nano-diamond (HND) films as our new study objects. The hard nanocarbon films were formed on silicon wafers and tungsten carbide (WC) substrates. The film properties of hardness, composition, structure, and friction were analyzed. The result of high density DLC film hardness is high, 80-90 GPa, with a low friction coefficient of less than 0.1.
  We have coated these onto cutting tools, conducted aluminum-alloy cutting experiments, and estimated their applicability. Results have suggested the degradation of cutting ability because of aluminum built-up; the cutting distance with a tungsten carbide tip was 20 m without coating and 200 m with a DLC coating. The cutting distance was extended to 4000 m with HND coating, which was a DLC film and nano-diamond multilayer. A high-density DLC film might even be extended up to 10000 m, that is, its lifetime could be lengthened to 50 times that of an ordinary DLC film.