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duces the porosity in surface layer and promotes healing of the pores under the action of
applied loads, that increases the corrosion resistance of porous titanium in 20% aqueous
solution of hydrochloric acid by one order.
It was investigated that the modification of porous titanium by thermodiffusion satu-
ration from a multicomponent medium with the formation of carboxide and carbonitride
coatings is either ineffective (20 % HCl) or provides very poor protection (40 % H SO ).
4
2
The reason for the weak anticorrosive protection of such coatings is the formation of an
inhomogeneous surface of protective films due to the peculiarity of the interaction of po-
rous titanium (including pores coming to the surface) with a multicomponent medium con-
taining gas and powder components.
In view of this, we focused on the organization of the anticorrosive protection by bi-
nary compounds (oxide and nitride).
By changing technological parameters of oxidation, a protective oxide film was
formed on the material surface; surface gas-saturated layer (solid solution of oxygen in α-
titanium); protective coating of oxide film and gas-saturated layer. This allowed us to rec-
ommend the morphology of the protective oxidized layer for porous titanium VT1-0 (ox-
ide film of 5...10 μm, gas-saturated layer of 50...60 μm), the best in terms of the anticorro-
sive protection, and to propose an oxidation regime for its formation. According to the re-
sults of metallographic and micro-XDS analyzes, such treatment heals surface pores on the
PM fabricated samples by oxide. The corrosion resistance of oxidized titanium increases
compared to the untreated one, and fabrication technology of titanium does not affect the
corrosion rate of the samples.
The kinetic studies of the isothermal saturation of titanium VT1-0 in nitrogen in the
temperature range of 800...900 ºC for 20 h showed that the constants of the parabolic rate
of nitriding of titanium fabricated by PM, depending on the level of the residual porosity

of samples, are one to three orders of magnitude higher compared to titanium fabricated
traditionally. Such intense saturation causes the formation of the phase-structural state of
the near-surface layers with the dominance of the diffusion layer. Moreover, the pores in
this layer are bordered by brittle and hard titanium nitride, which contributes to the local
embrittlement of the metal. Therefore, it was proposed two-stage nitriding, where in the
first stage a diffusion sub-layer was formed, and in the second one – nitride film. It was
determined that using recommended nitriding regimes; it is possible to influence the mor-
phology of the protective surface layers. Due to the modification of the surface layers ac-
cording to the recommended regimes, the nitride heals the pores coming to the surface of
the metal that reduces the corrosion rate by three orders of magnitude compared to the un-
treated titanium.
Keywords: porous titanium VT1-0, powder metallurgy, porosity, thermo-chemical
treatment, oxidation, nitriding, surface layers, anticorrosive properties

АННОТАЦИЯ

Шляхетка Х.С. Модифицирование поверхностных слоев пористого тита-
на ВТ1-0 для повышения антикоррозионных свойств - Рукопись.
Диссертация на соискание ученой степени кандидата технических наук по
специальности 05.02.01 - материаловедение. - Физико-механический институт им.
Г.В. Карпенко НАН Украины, Львов, 2021.