The challenge of decomposition and melting of gallium nitride under high pressure and high temperature

Gallium nitride (GaN) is considered to be one of the most important semiconductors nowadays. In this report a solution of the long standing puzzle regarding GaN decomposition and melting under high pressure and high temperaturę is presented.This includes the discussion of results obtained so far. The possibility of a consistent parameterisation of pressure (P) evolution of the melting temperaturę (Tm) in basic semiconductors (GaN, germanium, silicon…), independently from signs of dTm/dP is alsopresented

Создание и применение инструментальной керамики на основе сверхтвердых структурированных композитов

The state-of-the-art of development and improvement of superhard composites based on the cubic boron nitride have been considered. Such composites are used for equipment of cutting tools for machining of materials with high mechanical properties.Рассмотрены современные подходы к созданию и совершенствованию сверхтвердых композитов на основе кубического нитрида бора для оснащения режущих инструментов для обработки конструкционных материалов с высокими механическими свойствами

Information Technology for Genetic Algorithm Adaptation for Strategy Selection in Bimatric Games

Розроблено адаптацію генетичного алгоритму для рішення задач теорії ігор

Modelling and Experimental Investigation of Cutting Temperature when Rough Turning Hardened Tool Steel with PCBN Tools

In this study the cutting tool temperature that develops during rough turning of hardened cold-work tool steel is modelled on the basis of experimental data. The data obtained from a series of thermocouples, placed on a PCBN insert, into an anvil, and into a toolholder, were used as the input for the model. An inverse problem was solved, where the heat fluxes and heat transfer coefficients were computed and where the developed temperature field was reconstructed from the experimental readings. The temperature was modelled for the case of new tools, as well as for the case of its development in the course of tool wear. The machining case involved utilization of a high-cBN content and a binderless PCBN grade, both possessing high thermal conductivity of 110 and 190 W/m K respectively. (C) 2015 The Authors. Published by Elsevier B.V

Coherent phase transformations as a basis for production of highly textured polycrystals of boron nitride diamond-like phases

Some properties of high-textured polycrystals (HTP) are similar to the properties of single crystals. So, the materials on the base of HTP can be used instead of monocrystalline materials. Such replacement is especially actual for those crystalline materials the obtaining of which in the monocrystalline state is a problem. Cubic boron nitride (cBN) is one of such material. In present paper the method of massive HTP of cubic and wurtzitic BN obtaining is discussed. This method is based on the realization of coherent phase transformations in the CVD plates of graphite-like boron nitride under high pressures and temperaturesTranslated from Russian (Proceedings of Advanced Materials '99; Institute of Materials Science Problems, Nat. Acad. Sci. Ukraine, KievAvailable from British Library Document Supply Centre-DSC:9023.190(10101)T / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

EFFECTIVENESS OF THE LOOP-MEDIATED ISOTHERMAL AMPLIFICATION WITH FLUORESCENT DETECTION IN THE DIAGNOSIS OF PARVOVIRUS ENTERITIS IN CARNIVORES

The aim of the study was to evaluate the diagnostic value of the method of loop-mediated isothermal amplification of DNA with real-time fluorescent detection (real-time LAMP, or RT-LAMP) on the model of carnivore parvoviruses. Materials and methods. Samples of feces, blood and swabs from the rectum of different species of predatory animals with parvovirus enteritis (n = 39) and healthy animals (n = 31), as well as laboratory strains of mink enteritis virus, were analyzed by RT-LAMP using SYTO-9 and SYTO-82 dyes. Real-time PCR was used as a reference method. Results. In our study, the LAMP method with real-time fluorescence detection (RT-LAMP) in the carnivore parvovirus enteritis model provides high analytical sensitivity (1.5×103 copies of DNA/ml), diagnostic sensitivity and specificity (up to 100% under optimal conditions). Comparison of the two intercalating dyes showed that the SYTO-82 dye provides a higher signal-to-background ratio (22.6 ± 2.1) than the SYTO-9 dye (6.3 ± 1.5) (p <0.0000001 ). At the same time, SYTO-9 dye at the sensitivity limit (10 copies of DNA) provides an increase in fluorescence in the reaction mixture 13 minutes earlier than for SYTO-82 (23 and 36 minutes, respectively). Conclusion. RT-LAMP is a promising method for rapid and highly sensitive «point-of-care» diagnosis of infectious diseases, as well as in conditions of livestock farms or in field conditions

HP-HT sintering, microstructure, and properties of B6O- and TiC-containing composites based on cBN

The article presents a study of the potential for the use of B6O superhard boron suboxide as a binder in composite materials with a low cBN content. Superhard B6O is characterized by higher mechanical properties than TiC widely used in commercial materials today. Composites containing 60 vol % cBN and different binder compositions that included B6O and TiC have been sintered in a toroid-type high-pressure apparatus at a pressure of 7.7 GPa in a temperature range from 1500 to 2000 A degrees C. The microstructure, phase and elemental composition of the sintered materials have been examined via electron microscopy and X-ray diffraction analysis. Mechanical properties have been analyzed via indentation techniques. The performance of the cutting tools produced from the sintered composites has been evaluated in turning hardened cold work tool steel

Superhard pcBN tool materials with Ti₃SiC₂ MAX-phase binder: structure, properties, application

Superhard cutting tool materials were sintered in cBN–(Ti₃SiC₂–TiC) system via high pressure–high temperature method. Sintering was performed under the pressure 8 GPa in the 1400–2400 °C temperature range. The initial mixtures of three compositions were chosen with 90, 80 and 60 vol % cBN. The mixtures were prepared by mixing cBN (1–3 μm) and Ti₃SiC₂–TiC (< 2 μm). It was found, that upon sintering, the compositions of the obtained samples differed from the initial mixtures in all cases as a result of chemical reactions. Microstructure observations, phase composition estimation, and mechanical properties of the obtained tool materials were carried out. The results indicate that both the varying cBN content and the applied sintering conditions have a direct effect on the structure, properties, and kinetics of reactions.Надтверді матеріали системи cBN–(Ti₃SiC₂–TiC) при високому тиску і високій температурі. Спікання проводили при тиску 8 ГПа в температурному діапазоні 1400–2400 °С. Вихідні суміші трьох композицій були обрані з вмістом cBN 90, 80 і 60 % (за об’ємом). Суміші були приготовані шляхом змішування cBN (1–3 мм) и Ti₃SiC₂–TiC (< 2 мм). Було встановлено, що після спікання в результаті хімічних реакцій склад отриманих зразків відрізняється від складу вихідних сумішей. Проводили спостереження мікроструктури, оцінку фазового складу і механічних властивостей отриманих інструментальних матеріалів. Результати вказують на те, що різний зміст cBN і застосовані умови спікання чинять прямий вплив на структуру, властивості і кінетику реакцій.Сверхтвердые инструментальные материалы системы cBN–(Ti₃SiC₂–TiC) были спечены при высоком давлении и высокой температуре. Спекание проводили при давлении 8 ГПа в температурном диапазоне от 1400 до 2400 °С. Исходные смеси трех композиций были выбраны с содержанием cBN 90, 80 и 60 % (по объему). Смеси были приготовлены смешиванием порошков cBN (1–3 мм) и Ti₃SiC₂–TiC (< 2 мм). Было установлено, что после спекания в результате химических реакций состав полученных образцов во всех случаях отличается от состава исходных смесей. Проводили наблюдения микроструктуры, оценка фазового состава и механических свойств полученных инструментальных материалов. Результаты указывают на то, что разное содержание cBN и применяемые условия спекания оказывают прямое влияние на структуру, свойства и кинетику реакций