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for implants and medical instruments, parts of which are given colour to simplify the
selection of required shape and size.
It was determined that when modifying non-stoichiometric titanium nitride with
oxygen, nitrogen atoms are replaced by oxygen atoms with the formation of titanium
oxynitride TiNxO1-x on the surface, in which the nitrogen content is decreased, up to the
formation of titanium oxide TiO2. It was determined that by increasing the oxygen
content in titanium oxynitride and the appearance of the TiO2 oxide phase, the corrosion
resistance of the BT6 titanium alloy in a physiological environment is improved due to
an increase of the proportion of the ionic bonding in the coating compounds. It was
established that an increase of the oxygen content in the oxynitride leads to an increase
of the cytocompatibility of the BT6 titanium alloy, and the oxynitride layers of
composition TiN0.42O0.58 and TiN0.36O0.64 can be recommended for further testing of
their biological action in vivo.
The optimal composition of the electrolyte of (1М КОН + hydroxyapatite) for the
formation of HA coating on the titanium alloys for medical applications by the PEO
method was determined, which allows to form a porous HA coating with a spheroidal
structure and an optimal Ca/P ratio at a voltage of 160 V in a pulsed regime.
The regularities of formation of HA coatings on preformed nitride layers of Ti2N
and TiNx were established. It was shown that the corrosion resistance of the Ti2N+HA
coating in Ringer's solution is higher compared to TiNx+HA. It was established that the
value of Young's modulus for the HA coating deposited on the Ti2N nitride layer is close
to the corresponding value for a cortical bone.
It was established that with the transition from titanium nitride to oxynitride by
increasing oxygen content in the oxynitride, the Ca/P ratio is changed from values > 2
to the ratio characteristic of biological HA, which leads to an improvement of the
corrosion resistance of HA coating. The mechanisms of formation of HA coatings on
pre-modified surfaces of the titanium alloys for medical applications were established.
Keywords: commercially pure titanium BT1-0, titanium alloy ВT6, nitride and
oxynitride layers, hydroxyapatite coating, diffusion saturation, PEO, biocompatibility,
wear and corrosion resistance.