Проницаемость пористых сплавов на основе никелида титана с добавками титана, полученных методом диффузионного спекания

Выполнено исследование структурных особенностей пористых сплавов на основе никелида титана с различной концентрацией добавки Ti, полученных методом диффузионного спекания. Определены параметры макроструктуры порового пространства сплавов TiNi–Ti – коэффициенты пористости и проницаемости, средний размер пор и межпоровых перемычек. Увеличение концентрации добавок Ti ведет к уменьшению средних размеров пор и увеличению средних размеров межпоровых перемычек. Исследованы коэффициенты проницаемости пористых материалов, полученных методами диффузионного спекания и СВС. Установлено, что коэффициенты проницаемости образцов, полученных разными методами, существенно отличались несмотря на схожие коэффициенты пористости. Это может быть объяснено тем, что экспериментальные образцы, полученные разными методами, имеют отличающуюся структуру поровых каналов: СВС-материал имеет регулярную взаимосвязанную пористую структуру, а спеченный материал – менее взаимосвязанные поры в продольном направлении, что в совокупности с малым размером пор затрудняет течение жидкости в материале

Получение биосовместимых пористых сплавов на основе никелида титана методами СВС и спекания

В статье рассматривается проблема получения сплавов на основе никелида титана (TiNi). Значительное внимание уделяется производству пористых проницаемых сплавов на основе TiNi. Существуют различные способы получения сплавов на основе TiNi, но многие из них требуют дорогостоящего оборудования, а также имеют недостатки, такие как продолжительность синтеза и получение недостаточно чистого продукта. Сегодня для получения пористых материалов широко используются методы самораспространяющегося высокотемпературного синтеза (СВС) и спекания, основным преимуществом которого является возможность получения пористых материалов с регулируемыми характеристиками структуры и физико-механическими свойствами. Поэтому целью данной работы является определение параметров СВС и спекания

Production of two-dimensional porous TiNi-based powder material by diffusion sintering and electron-beam processing

The paper addresses the study of the surface condition of two-dimensional porous TiNi-based powder materials produced by diffusion sintering and electron-beam processing. Methods of production of two-dimensional TiNibased materials to be used for the purposes of non-destructive testing have been proven. The surface condition of the produced materials is described by scanning electron microscopy and interference profilometry

On the Issue of Nitrogen Solubility in Chromium-Nickel Grades of Steels

The article presents a comparative analysis of the solubility of nitrogen in chromium-nickel grades of steels. It is revealed that the existing theoretical calculations on the solubility of nitrogen in chromium-nickel steels can be applied only to austenitic grades of steels

Investigation of the effect of copper addition on physical and mechanical properties of TiNi-Cu porous alloy

This work is devoted to the physical and mechanical properties of porous alloys based on TiNi alloyed with different amounts of Cu additive. We show that by doping a porous TiNi alloy with copper instead of nickel, it is possible to obtain characteristics acceptable for use in implantology and superior to those of known porous TiNi alloys. Cu addition in the range from 1 to 10 at.% is shown to optimize the properties of tested alloys. There is a decrease in the minimal martensitic transformation stress τminMs from 37 to 17 MPa when compared to initial unalloyed TiNi. Alloys with 3 and 6 at.% of Cu are found to be optimal for use in medical practice. Along with a wide temperature range of reversible deformations that cover the range of operating temperatures (273–313 K), such alloys demonstrate their martensitic transformation stress values below 28 MPs. This permits to model implantable structures of complex configuration from such materials under a certain temperature regime

Structural Features of TiNi-based Textile Materials and Their Biocompatibility with Cell Culture

This study investigates the structural features of TiNi-based textile materials. It is established that woven materials have a regular cellular structure, while knitted mesh materials are characterized by presence of cells with various sizes both in the longitudinal and cross directions. The surface oxide layer of threads has a microporous structure that provides the improved adaptation in organism tissues. It is shown that the fibroblast colonization rate of the knitted mesh implants depends on the cell size and quantity of mesh knots. Smaller cells are quicker colonized. Mesh knots are the centers of the cell cling. The feature of cell interaction with the tread surface of various sizes is analyzed

Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector

The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV for the direct photon emission in the K- --> pi- pi0 gamma decay has been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV/c negative secondary beam of the U-70 PS. The value Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930 completely reconstructed events is consistent with the average value of two stopped-kaon experiments, but it differs by 2.5 standard deviations from the average value of three in-flight-kaon experiments. The result is also compared with recent theoretical predictions.Comment: 13 pages, 8 figure

Gold-plated Mode of CP-Violation in Decays of B_c Meson from QCD Sum Rules

The model-independent method based on the triangle ideology is implemented to extract the CKM-matrix angle gamma in the decays of doubly heavy long-lived meson B_c. We analyze a color structure of diagrams and conditions to reconstruct two reference-triangles by tagging the flavor and CP eigenstates of D^0 meson in the fixed exclusive channels. The characteristic branching ratios are evaluated in the framework of QCD sum rules.Comment: 11 pages, RevTeX4 file, 4 eps-figure

Preparation of porous TiNi-Ti alloy by diffusion sintering method and study of its composition, structure and martensitic transformations

The study demonstrates a method for controlling not only the phase composition but also the atomic composition of TiNi matrix in porous TiNi-Ti alloys developed for biomedical uses as implants. The alloys were obtained from TiNi powder which was sintered with Ti powder added at as much as 0–10 at%. The structure, phase and chemical composition of the produced TiNi-Ti alloys was investigated with respect to the amount of Ti added into the material. It is shown that in the sintered product containing 5 at% and more of Ti additive, the composition of its TiNi matrix becomes close to equiatomic (with Ti:Ni atomic ratio ~1), and the excessive Ti precipitates as secondary phases Ti2Ni and Ti3Ni4. In parallel, with increase in Ti ad- ditive from 0–10 at%, the structure of the precipitating Ti2Ni type phases changes its morphology from separate spherical or pyramidal precipitates to large dendritic formations. The direct martensitic trans- formation from austenite to martensite in all the samples was found to proceed in two stages and through the R-phase (B2→R→B19′). Thermoresistive analysis demonstrated that TiNi-Ti samples with 5 and more at% of Ti had their characteristic starting temperature of martensite transition stabilizing at ~57 °C (330 K). This implies that the sample with 5 at% of Ti additive exhibited desired martensite transition temperatures, while containing a minimum concentration of secondary-phase precipitates in its matrix which deteriorate its properties. Thus, for the 곙rst time, we show that a very simple preparation approach based on sintering powders of TiNi and Ti is capable of producing porous TiNi-Ti alloys with properties optimized for fabricating bone implants