Fractography of Fatigue Fracture Surface in Silumin Subjected to Electron-Beam Processing

The surface modification of the eutectic silumin with high-intensity pulsed electron beam has been carried out. Multi-cycle fatigue tests were performed and irradiation mode made possible the increase in the silumin fatigue life more than 3.5 times was determined. Studies of the structure of the surface irradiation and surface fatigue fracture of silumin in the initial (unirradiated) state and after modification with intense pulsed electron beam were carried out by methods of scanning electron microscopy. It has been shown, that in mode of partial melting of the irradiation surface the modification process of silicon plates is accompanied by the formation of numerous large micropores along the boundary plate/matrix and microcracks located in the silicon plates. A multi-modal structure (grain size within 30-50 μm with silicon particles up to 10 [mu]m located on the boundaries) is formed in stable melting mode, as well as subgrain structure in the form of crystallization cells from 100 to 250 [mu]m in size). Formation of a multi-modal, multi-phase, submicro- and nanosize structure assisting to a significant increase in the critical length of the crack, the safety coefficient and decrease in step of cracks for loading cycle was the main cause for the increase in silumin fatigue life

Metal micro-detectors: development of “transparent” position sensitive detector for beam diagnostics

Metal Micro-strip Detector (MMD) represents a novel position sensitive detector for wide range of applications. The main advantages of MMD are low thickness, high radiation resistance and high spatial resolution. MMD production technology includes some stages: micro-strip layout made by photo-lithography on silicon wafer, plasma-chemistry etching of the silicon wafer in the operating window, micro-cabling connection to the readout electronics and DAQ. Commercially available read-out systems (VA_SCM3 microchip preamplifier, Time Pix readout chip, Gotthard, X-DAS) have been studied for use with MMD. Characterization studies of the MMD are presented in details.Металлический микростриповый детектор (ММД) представляет собой новый позиционно- чувствительный детектор для широкого спектра применений. Основные преимущества ММД: малая толщина, высокая радиационная стойкость, высокое пространственное разрешение. Технология производства ММД включает в себя несколько этапов: микростриповая структура создается при помощи фотолитографии на кремниевой пластине, плазмо-химическое травление кремниевой пластины в рабочем окне, подключение микро-кабелем к считывающей электронике. Коммерчески доступные системы считывания и обработки данных (VA_SCM3, TimePix, Gotthard, X-DAS) были изучены для использования с ММД. Представлены результаты исследований MMD на пучках разных частиц.Металевий мікростріповий детектор (ММД) являє собою новий позиційно-чутливий детектор для широкого спектру застосувань. Основні переваги ММД: мала товщина, висока радіаційна стійкість, висока просторова роздільна здатність. Технологія виробництва ММД включає в себе кілька етапів: мікростріпова структура створюється за допомогою фотолітографії на кремнієвій пластині, плазмо-хімічне травлення кремнієвої пластини в робочому вікні, підключення мікро-кабелем до зчитуючої електроніки. Комерційно доступні системи зчитування й обробки даних (VA_SCM3, TimePix, Gotthard, X-DAS) були вивчені для використання з ММД. Представлено результати дослідження MMD на пучках різних частинок

Structure and properties of commercially pure titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator

The paper analyzes the surface structure and properties of commercially pure VT1-0 titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator. The analysis demonstrates that the friction coefficient of the nitrided material decreases more than four times and its wear resistance and microhardness increases more than eight and three times, respectively. The physical mechanisms responsible for the enhancement of strength and tribological properties of the material are discussed

Surface structure of commercially pure VT1-0 titanium irradiated by an intense pulsed electron beam

It is shown that pulsed electron beam irradiation of commercially pure titanium at a beam energy density of 10 J/cm{2}, pulse duration of 150 [mu]s, number of pulses of N=5 pulses, and pulse repetition frequency of 0.3 Hz with attendant polymorphic [alpha]->[beta]->[ alpha] transformations allows a more than five-fold decrease in the grain and subgrain sizes of the material structure

Combined surface modification of commercial aluminum

The paper analyzes research data on the structure and properties of surface layers of commercially pure A7-grade aluminum subjected to treatment that combines deposition of a thin metal film, intense pulsed electron beam irradiation, and nitriding in low-pressure arc plasma. The analysis shows that the combined method of surface modification provides the formation of a multilayer structure with submicro- and nano-sized phases in the material through a depth of up to 40 ?m, allowing a manifold increase in its surface microhardness and wear resistance (up to 4 and 9 times, respectively) compared to the material core. The main factors responsible for the high surface strength are the saturation of the aluminum lattice with nitrogen atoms and the formation of nano-sized particles of aluminum nitride and iron aluminides

The accumulation of femtosecond laser radiation energy in crystals of lithium fluoride

We present the results of studies of energy accumulation during the non-destructive interaction of extremely intense near infrared laser radiation with model wide band gap dielectric crystals of lithium fluoride, when the intensity of pulses is sufficient for effective highly nonlinear absorption of light and for the excitation of the electron subsystem of matter and the energy of pulses is still not sufficient for significant heating, evaporation, laser breakdown or other destruction to occur. We studied the emission of energy in the form of light sum of thermally stimulated luminescence accumulated under conditions of self-focusing and multiple filamentation of femtosecond laser radiation. It was established that it's the F2 and F[3]{+} color centers and supplementary to them centers of interstitial type which accumulate energy under the action of a single femtosecond laser pulses. When irradiated by series of pulses the F3, F[3]{-} and F[4] centers additionally appear. F2 centers are the main centers of emission in the process of thermally stimulated luminescence of accumulated energy. The interstitial fluoride ions (I-centers) are the kinetic particles. They split off from the X[3]{-} centers in the result of thermal decomposition of latter on the I-centers and molecules X[2]{0}. I-centers recombine with F[3]{+} centers and form F[2] centers in excited state. The latter produce the characteristic emission spectrum emitted in the form of thermally stimulated luminescence

Особенности биохимических параметров крови и экссудата у больных туберкулезным экссудативным плевритом

Some biochemical indicators of peripheral blood and pleural fluid (level of the total protein, glucose, lactate dehydrogenase activity) at patients with various variants of tubercular exudative pleurisy (MBT-positive and MBT-negative) for the purpose of definition of possibility of use this indicators as criteria for differential diagnostics of a pleurisy, have been studied. It has been established that tubercular exudative pleurisy is characterized by the expressed changes of the biochemical status of blood and pleural fluid in comparison with that at healthy donors and patients with not tubercular exudative pleurisy, however, this changes in most cases are nonspecific and don't depend on a variant of tubercular exudative pleurisy.Изучены некоторые биохимические показатели периферической крови и плеврального экссудата (уровень общего белка, содержание глюкозы, активность лактатдегидрогеназы) у больных с различными вариантами туберкулезного экссудативного плеврита (МБТ-позитивный и МБТ-негативный) с целью определения возможности использования данных показателей в качестве критериев для дифференциальной диагностики плевритов. Установлено, что туберкулезный экссудативный плеврит характеризуется выраженными изменениями биохимического статуса крови и плеврального экссудата по сравнению с таковым у здоровых доноров и пациентов с экссудативным плевритом нетуберкулезного генеза, однако данные изменения в большинстве случаев являются неспецифическими и не зависят от варианта туберкулезного экссудативного плеврита

Investigation of the influence of oxygen on the rate and anisotropy of deep etching of silicon in the plasma-chemical reactor with the controlled magnetic field

The article presents the research results on the influence of the amount of oxygen in a mixture with sulfur hexafluoride on the rate and anisotropy of the silicon etching in the plasma-chemical reactor with the controlled magnetic field. The etching was performed under the pressure of (0,3-2,0)·10-3 Torr in the working chamber and the energy of chemically active ions of 50-80 eV. It was possible to etch the silicon to the depth of 100 Вµm with anisotropy 10, using a thick (0.4-1 µm) nickel mask. The obtained results make it evident, that maximums do not coincide for speed of etch and anisotropy. The maximum of etch rate is observed at oxygen maintained at 5%. While the maximum of anisotropy is observed at 10% oxygen. The authors discovered the influence of the magnetic field on the rate and anisotropy of etching. Etch rate of the silicon at the increase of the magnetic-field tension increases virtually twofold at other discharge parameters remaining unchanged. The anisotropy first increases, and then decreases sharply. Thus, the increase of the tension of magnetic field results in worsening of anisotropy. Thus, the process of deep plasma-chemical etching of silicon has been developed and optimized