The fatigue behavior of vapor-deposited carbon films

Vapor-deposited carbon films (about 4000 to 5000 A thick) on stainless steel substrate were cyclically loaded to 10(6) cycles. The carbon films did not fail in fatigue at strain levels up to 13.12 x 10(-3). Rather, the failure in the carbon film occurred as a result of plastic deformation in the substrate; i.E., the failure was directly related to the endurance limit of the substrate material, which, when expressed as strain, was measured in this study to be about 8.0 - 10.88 x 10(-3). The endurance limit was also found to be very close to the elastic strain limit of the substrate. The implications of the findings for the use of carbon coated components in prosthetic devices are also discussed.