Effect of Nanocrystalline Diamond Films Deflection on Wear Observed in Reciprocating Sliding Tests

The present study deals with the tribological behavior of nanocrystalline diamond (NCD) films. The diamond films were deposited by microwave plasma enhanced chemical vapor deposition (MPCVD) in methane/hydrogen/air plasma on the Si(100) substrates. The tribological properties were studied by reciprocal sliding tests against Si3N4 balls. The depth profiles and surface morphology of the wear scars were investigated by means of mechanical profilometry and scanning electron microscopy (SEM). Various adaptation processes occur between contacting surfaces including asperity polishing, formation of carbonaceous tribolayer and ripple patterns on the wear scar surfaces. The film deflection is the specific form of adaptation decreasing contact pressure and, therefore, the damage (including wear) of both counter bodies. The deflection of NCD films in sliding tests can be related with the effect of fatigue

Measurement of the complex permittivity of polycrystalline diamond by the resonator method in the millimeter range

An improved resonator method is developed, which allows for a change in the resonator coupling coefficient at insertion of the sample during the measurement of the imaginary part of the material permittivity. The method makes it possible to measure small samples. The permittivity at a frequency of 27GHz is measured for rods made of polycrystalline CVD diamond plates of 57 and 100mm in diameter grown in the microwave plasma in methane-hydrogen mixtures, and the loss tangent tan delta is determined at a level of the order of 10(-3)