Diffusion Degradation of Carbon Coatings on Various Metallic Substrates

摘要

Carbon belongs to the class of materials with large field of potential applications. Particularly, the novel forms of carbon can be very advantageous in form of rather thin coatings deposited on various substrates. Unfortunately, in case of metallic substrates the carbon diffusion into the substrate during the deposition and during the life-time of the coated part can deteriorate drastically its properties. For the deposition of diamond-like coatings the novel industrial vacuum arc apparatus Nikolay was used which allows one to coat the large area parts with dimensions up to 2100x1400 mm. This apparatus comprises the novel Hall current accelerator for ionic cleaning and implantation of substrates. The accelerator has a large aperture of 1400 mm and a power up to 10 kW. The diamond-like coating was deposited simultaneously in the identical conditions on the polished substrates of polycrystalline austenitic stainless steel (with fcc structure), ferritic low-carbon steel (with bcc structure), copper and (for comparison) on silicate glass. Depth profiles measured with the aid of secondary-ion mass spectroscopy are presented. The carbon profile on the the carbon profile was observed. On the contrary, the diamond-like coatings on both steel substractes were almost completely dissolved in the substrates. Therefore, the special interlayers has to be deposited on the steel substrate in order to prevent the duffusion deterioration of carbon coalings. The role of the grain boundary diffusion and grain boundary phase transformation is also discussed.