Determination of sp2/sp3 Fractions in Diamond-Like Carbon Coatings on a Tungsten–Cobalt Base Using CKLL Auger Spectra

The elemental composition and chemical bonds in a diamond-like carbon film on the surface of a tungsten–cobalt alloy base were studied using X-ray photoelectron spectroscopy. The ratios of sp2/sp3 bond fractions were determined using various parameters of the CKLL Auger spectra excited in X-ray photoelectron spectrometers; the average values were 0.32/0.68. It was revealed that the tribological interaction of a counterbody in the form of an aluminum oxide ball with the base material begins with a friction coefficient of approximately 0.4, and with the diamond-like film surface with a friction coefficient of approximately 1.0. With further sliding, starting from approximately 25,000 sliding cycles, the friction coefficient with the tungsten-cobalt base increases to ~0.65, and the friction coefficient with the diamond-like film drops to values of ~0.50. In the range of 20 000–25 000 sliding cycles, the friction coefficient of the counterbody on the diamond-like film drops to ~0.32, then returns to 0.62. The values characterizing the wear of the counterbody when interacting with a hard alloy base are higher than when interacting with the surface of the diamond-like film. The results confirm that films of this type are technologically feasible for use in friction units that require a combination of high deformation resistance under heavy loads and high corrosion resistance at high temperatures and in adverse environmental conditions.