The effect has been studied of treatment with nanosecond laser pulses on the fatigue resistance of plate samples of recrystallized (grain size of the order of 2-3 μm) commercially pure titanium (grade VT1-0) under cyclic tensile loading. The results of investigations by scanning and transmission electron microscopy of the subsurface layer microstructure of the alloy under study after exposure to nanosecond laser irradiation and subsequent fatigue tests are presented. Keywords: titanium, surface, pulsed nanosecond laser irradiation, shock-wave action, fatigue properties.

The effect of treatment with nanosecond laser pulses on the fatigue resistance of plate samples of recrystallized (grain size of the order of 2-3 µm) commercially pure titanium (grade VT1-0) under cyclic tensile loading is studied. The results of investigations by methods of scanning and transmission electron microscopy of the microstructure of the subsurface layer of the alloy under study after exposure to nanosecond laser irradiation and subsequent fatigue tests are presented.

The paper presents an overview of previously published and original results of studies of the structure, phase composition, mechanical and other properties of the near-surface layers and bulk samples of titanium and nickel-based alloys at various types of surface processing, including irradiation with short and ultra-short laser pulses, application of bioactive coatings by microarc oxidation (including in combination with laser treatment) and diffusion nitrogen saturation (bulk nitriding). The regularities of changes in the structure of thin surface layers of titanium alloys as a result of irradiation with short (nanosecond laser irradiation) and ultrashort (femtosecond laser irradiation) laser pulses were revealed. The features of the forming structure in the process of diffusion saturation of the alloy with nitrogen on the basis of the Ni-Co-Cr-Ti-(X) system are considered. The possibilities of formation of bioactive calcium phosphate coatings on titanium alloys for medical purposes by microarc oxidation are discussed.

We studied the influence of the characteristics of oxide porous coatings on osteogenesis and integration of new bone tissue and titanium implant surface in the ectopic osteogenesis test. Implants with coating with pore size 2-20 μ exhibit better osteogenic and osteoconductive characteristics than implants with homogenous surface and smooth relief (pore size 0.5-5.0 μ). Physical characteristics of the surface of the material along with chemical composition of the coating are essential for the formation of bone tissue and its integration with the implant.

Исследовано влияние микродугового биоактивного покрытия на циклическую прочность при испытаниях на изгиб крупнозернистого титанового сплава ВТ6 и наноструктурированного технически чистого титана ВТ1-0. Использовали два вида покрытий, отличающихся по толщине, размеру пор и элементному составу. При нанесении покрытий на технически чистый титан ВТ1-0 и титановый сплав ВТ6 использовались разные режимы микродугового оксидирования. Установлено, что МДО покрытия исследованных типов снижают условный предел выносливости (на базе 106 циклов) обоих материалов на 30?60 % при различных коэффициентах асимметрии цикла R. На кривой Вёллера в двойных логарифмических координатах для образцов с покрытием отсутствует излом, свидетельствующий о переходе на многоцикловую усталость. Методами растровой электронной микроскопии исследована топография усталостных изломов.

Методами растровой и просвечивающей электронной микроскопии исследованы морфология поверхности, элементный состав и структура пористых биопокрытий и переходного слоя между металлом-основой (титановый сплав ВТ-6) и биопокрытиями, полученными методом микродугового оксидирования по оригинальным технологическим режимам. Изучены два вида покрытий, сформированных по различным режимам и отличающихся по толщине, параметрам пористости и составу. Исследовано влияние биопокрытий на циклическую прочность и условный предел выносливости (на базе 107 циклов) при испытаниях на изгиб титанового сплава ВТ6. Обсуждаются возможные причины снижения сопротивления усталости образцов исследуемого сплава после нанесения покрытий.

The thermomechanical stability of nanostructured (NS) commercially pure titanium is studied in the temperature range of 20–600°C using the method of dynamic mechanical analysis. It has been found that the maxima observed in the temperature dependence of the loss angle tangent (t = 350–600°C for the analyzed cyclic loading frequencies of 0.33–10 Hz) are of relaxation nature. The measured activation energies of microplastic deformation are close to the corresponding literary data on the experimental activation energies of the grain-boundary sliding under the studied conditions. The thermomechanical stability of NS VT1-0 titanium for medical application has been experimentally estimated up to 1.2 × 10 6 cycles of loading with cantilever bending at t = 100°C, which is substantially higher than the operating temperature (t = 37°C).

The influence of both, the composite material based on the protein-mineral components including the prolonged form of the recombinant human bone morphogenetic protein 2 (rhBMP-2) and the method of the titanium implant's surface treatment, on the reparative osteogenesis and adhesion strength of the bone tissue - implant's surface contact was evaluated. Covering of implants with the composite coating promotes significant acceleration of the bone tissue regeneration processes in the site of implants loading. The composition coating with prolonged form of the rhBMP-2 promoted increasing of the neogenic bone tissue's adhesion with the implants, as compared with the coating without recombinant human bone morphogenetic protein. The implants treated with microarc oxidation demonstrated higher values of the breakout force during the separation of the implants from the bone than the implants treated with sandblasting method.