Page 7 - Докторська дисертація_Ткачук

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determined that the wear resistance of nitrided BT6 titanium alloy in a tribo-pair with

UHMWPE in a 10% aqueous solution of chondroitin sulfate is better when a nitride

layer based on the Ti2N phase with lower roughness and surface microhardness is

formed on the surface, the formation of which is provided by the saturation in the range

of low temperatures and long exposures in a rarefied nitrogen. It was shown that the

corrosion resistance of nitrided BT6 titanium alloy in physiological solutions that

simulate the physiological environment of a human body is better when a nitride layer

based on titanium mononitride TiNx is formed on the surface, the formation of which

is ensured by the saturation in the range of high temperatures and short exposures at

atmospheric pressure of the nitrogen.

The stage nitriding regime for commercially pure titanium BT1-0 was

developed. It provides high leveling of tribological and anti-corrosion characteristics of

the surface in physiological solutions. Testing by using the T-24 simulator of the

biomechanical human motion showed that the wear intensity of the UHMWPE cup in

a tribo-pair with a nitrided titanium head is 3 times lower than that of a tribo-pair with

CoCrMo. It was established that the surface nitrided by developed saturation method

improves the cytocompatibility of titanium, which allows to conduct studies in vivo.

The scientific approaches to the formation of oxynitride layers on titanium

alloys from a controlled nitrogen-oxygen-containing gas environment, both in a

rarefied (0.001…0.1 Pa) nitrogen-oxygen-containing gas environment (an air) and

saturation in rarefied nitrogen with the addition of 20 and 30 vol.% of oxygen

(nitrogen-oxygen-containing gas mixture) were developed. The temperature range

(500...750°C) for the formation of oxynitride layers was established. It was

determined that with a decrease of the oxygen content in the nitrogen-oxygen gas

mixture from 30 to 20 vol.%, the corrosion resistance of oxynitrided titanium is

increased regardless of the oxynitriding temperature. It was established that by

influencing the ratio of nitrogen and oxygen in titanium oxynitride, it is possible to

form both oxynitrides of equiatomic composition and those enriched with nitrogen or

oxygen, while changing the surface colour from violet, gray-violet to golden or green,