Coatings of CNx have been prepared on the substrates of material Ti6Al4V, of which the big human joint replacements are made. The deposition of the CNx coating was carried out by PACVD method in apparatus with standard arrangement. The methane and nitrogen have been used as precursors for CNx compound. The infrared absorption spectroscopy and Rutherford backscattering spectroscopy were applied on diagnostics of prepared CNx layer. Beside carbon and nitrogen the hydrogen and oxygen were found in the coatings. The sliding tests were carried out with the samples. The counter parts were the cylinders made of the polyethylene of the same type as for big joint prostheses is used. The tests were carried out in the medium of physiological solution. The CNx coatings perform well under the lower load of 25 and 50 N. When the load is increased to 100 N, the friction coefficient slowly increases, but measured values of µ are typical for boundary lubrication.
