Investigation of the Aluminum Nitride Formation During the Aluminum Nanopowder Combustion in Air

The phase formation sequences, intermediate and final products of aluminum nanopowder combustion are studied. The experiments were performed in the Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, at the “Precision Diffractometry II” station (SR beamline No. 6 of the VEPP-3 electron storage ring). The main combustion product was found to be aluminum nitride. In the combustion of aluminum nanopowder aluminum ?-oxide is the first to form, and aluminum nitride arises next. The formation of aluminum nitride probably occurs by successive replacement of oxygen by nitrogen from the aluminum oxide. The use of synchrotron radiation with high photon flux made it possible to determine with moderate time resolution the sequence of stages of formation of crystalline products during combustion of the aluminum nanopowder

Investigation of the Aluminum Nitride Formation During the Aluminum Nanopowder Combustion in Air

The phase formation sequences, intermediate and final products of aluminum nanopowder combustion are studied. The experiments were performed in the Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, at the “Precision Diffractometry II” station (SR beamline No. 6 of the VEPP-3 electron storage ring). The main combustion product was found to be aluminum nitride. In the combustion of aluminum nanopowder aluminum ?-oxide is the first to form, and aluminum nitride arises next. The formation of aluminum nitride probably occurs by successive replacement of oxygen by nitrogen from the aluminum oxide. The use of synchrotron radiation with high photon flux made it possible to determine with moderate time resolution the sequence of stages of formation of crystalline products during combustion of the aluminum nanopowder

Study of Aluminium Nanopowder Combustion by Method of Laser-Speckle Correlation

In this paper, we discuss an application of the method of laser-speckle correlation for studying the combustion process of aluminium nanopowder in air and its mixture of iron nanopowder. It is suggested to characterize the combustion process using the statistic parameter - correlation coefficient. The principle of observation is explained and the experimental schema for investigating is provided. The differences between aluminium nanopowder and its mixture with iron nanopowder are also considered

Properties of nickel-phosphorous coatings codeposited by the electroless and electrochemical plating process

At present, despite numerous studies and practical application, the process of chemical nickel plating remains imperfect. The low nickel deposition rate, the high consumption of the solution components, and the complexity of the deposition process do not contribute to the widespread use of chemical nickel plating. At the same time, chemically deposited coatings are significantly different from the electrochemical: they possess valuable properties. In the paper, the intensification method of chemical nickel plating considered through the use of the co-deposition process with chemical and electrochemical methods. The co-deposition was carried out in an acidic electrolyte solution on an aluminum plate with the stationary potential shift from - 0.01 to - 0.25 V with the use of three electrode system. The presented technique of intensification due to the combination of nickel deposition processes by chemical and electrochemical methods is able to increase the deposition rate of the coatings, and also allows influencing their composition and mechanical properties

Preparation and properties of composite material based on hafnium diboride and aluminum

Hafnium diboride (HfB[2]) in aluminum matrix (Al) material was prepared by diffusion sintering of a mixture of hafnium diboride and aluminum micropowders. The effect of the hafnium diboride content (HfB[2]) in the aluminum matrix (Al) on sintering characteristics and properties of the samples is presented. The effect of microwave activation of the aluminum powders has been established. The diffusion sintering behavior was concluded. The material properties and structure were defined

Study of aluminium nanopowder combustion by method of laser-speckle correlation

In this paper, we discuss an application of the method of laser-speckle correlation for studying the combustion process of aluminium nanopowder in air and its mixture of iron nanopowder. It is suggested to characterize the combustion process using the statistic parameter - correlation coefficient. The principle of observation is explained and the experimental schema for investigating is provided. The differences between aluminium nanopowder and its mixture with iron nanopowder are also considered

Preparation and properties of composite material based on hafnium diboride and aluminum

Hafnium diboride (HfB2) in aluminum matrix (Al) material was prepared by diffusion sintering of a mixture of hafnium diboride and aluminum micropowders. The effect of the hafnium diboride content (HfB2) in the aluminum matrix (Al) on sintering characteristics and properties of the samples is presented. The effect of microwave activation of the aluminum powders has been established. The diffusion sintering behavior was concluded. The material properties and structure were defined

Low temperature sintering of corundum powders

Relevance of the research is caused by the necessity of profound processing of raw mineral and perfection of technology of obtaining alumoxide ceramic. The main aim of the research is to develop the activation methods of ceramic sintering based on corundum Al2O3 by mechanic treatment of powders in a planetary mill, additions of Al, Al2O3 nanopowder and TiO2 submicrom powder in a mixture, application of spark plasma sintering method. The methods: sieve analysis of a large-scale powder dispersion using the analyzer A20, x-ray phase analysis of the studied samples, hydrostatic weighting for determining a conditional density of the sintered samples, measuring microhardness of the sintered samples using microhardness tester PMT-3, measuring HRA hardness by the Rockwell hardness tester. The results. Addition of Al2O3 nanopowder in GK-5 corundum contributed to increase of sintering ceramic density and microhardness. Such activation effect is explained by the increase of interparticle contact area, which is related to Al2O3 nanopowder addition. Sintering activation is caused by high structural activity and surface energy of Al2O3 nanopowder, which are determined by crystal structure deficiency and particle small size. The most significant rise in density was observed for ceramic, containing 5…20 wt. % of Al2O3 nanowpoder. Additional activation of Al2O3 nanopowder sintering when adding aluminum nanopowder: its porosity decreased, was proved by the experiment. Sintering activation by adding Al nonopowder is explained by aluminum oxidation and phase transformation (Hedvall effect). TiO2 nanopowder additive in Al2O3 powder had the maximum activation effect: the density of sintering ceramic, containing 1,5 wt. % TiO2, achieved 3,48 g/cm3

Energy storage in aluminum nanopowder in stress-strain state of crystal lattice

When transforming metals into nanodispersed state nanopowders acquire new properties, including the storage of energy by nonopowders. The increasing interest to aluminum powders and nanopowders is caused by their application as a high-energy additive in rocket fuels and pyrotechnic mixtures. Thus, the investigation of energy storage in Al nanopowder is of great importance. Besides, it is not easy to determine the amount of stored energy in Al nanopowder. The authors have used the aluminum nanopowder obtained by electrical explosion of aluminum wire in argon, using UDP-4D installation developed in Tomsk Polytechnic University. The main aim of the study is to asses experimentally the value of energy, stored in the form of stress-strain state of the crystal lattice of Al nanopowder and to compare the obtained value to a general value of stored energy. The methods used in the study are the X-Ray diffraction, differential thermal analysis. It was ascertained that the crystal lattice is in stressed state in air-passivated electroexplosive aluminum nanopowder. The modified Lorenz function was used as a profile function; crystalline microdistortions, calculated by the approximation technique, amount to 8,66 x 10[-4]. The value of energy, stored in the stress-strain state of the crystal lattice of electroexplosive aluminum nanopowder, is 0,385 J/g, while the value of stored energy, determined by means of differential thermal analysis, is 348 J/g. Thus, the most feasible mechanism of storing significant energy in aluminum nanopowder is the formation of more energy-saturated structures in solid (the formation of a double electric layer with pseudocapacity during passivation)

Energy storage in aluminum nanopowder in stress-strain state of crystal lattice

При переводе металлов в нанодисперсное состояние наблюдается появление новых свойств нанопорошков, в том числе запасание нанопорошками энергии. Возрастающий интерес к порошкам и нанопорошкам алюминия обусловлен их использованием в качестве высокоэнергетических добавок в ракетные топлива и пиротехнические смеси. Актуальность исследования связана с необходимостью установления механизмов запасания энергии нанопорошком алюминия. Вместе с тем существенной проблемой является определение величины запасенной энергии в нанопорошке Al. В работе использовали пассивированный малыми добавками воздуха нанопорошок алюминия, полученный методом электрического взрыва алюминиевы проводников в среде аргона с помощью установки УДП-4Г, разработанной в Томском политехническом университете. Цель работы: экспериментально установить величину энергии, запасаемой в форме напряженно-деформированного состояния кристаллической решётки нанопорошка алюминия и сравнить с общей величиной запасенной энергии. Методы исследования: дифракционные рентгеноструктурные исследования, дифференциальный термический анализ. Результаты. Установлено, что в пассивированном воздухом электровзрывном нанопорошке алюминия кристаллическая решётка находится в напряженном состоянии. Модифицированная функция Лоренца была выбрана в качестве аппроксимирующей, микроискажения кристаллитов, рассчитанные методом аппроксимаций, составляют 8,66 х 10[-4 ]. Величина энергии, запасаемой в напряженно-деформированном состоянии кристаллической решётки электровзрывного нанопорошка алюминия, - 0,385 Дж/г, в то время как определенная с помощью дифференциального термического анализа запасенная энергия составляет 348 Дж/г. Таким образом, вероятным механизмом запасания значительной энергии нанопорошком алюминия является формирование более энергонасыщенных структур в твердом теле (в том числе, за счёт формирования на поверхности нанопорошка алюминия при пассивировании двойного электрического слоя, обладающего псевдоемкостью).When transforming metals into nanodispersed state nanopowders acquire new properties, including the storage of energy by nonopowders. The increasing interest to aluminum powders and nanopowders is caused by their application as a high-energy additive in rocket fuels and pyrotechnic mixtures. Thus, the investigation of energy storage in Al nanopowder is of great importance. Besides, it is not easy to determine the amount of stored energy in Al nanopowder. The authors have used the aluminum nanopowder obtained by electrical explosion of aluminum wire in argon, using UDP-4D installation developed in Tomsk Polytechnic University. The main aim of the study is to asses experimentally the value of energy, stored in the form of stress-strain state of the crystal lattice of Al nanopowder and to compare the obtained value to a general value of stored energy. The methods used in the study are the X-Ray diffraction, differential thermal analysis. It was ascertained that the crystal lattice is in stressed state in air-passivated electroexplosive aluminum nanopowder. The modified Lorenz function was used as a profile function; crystalline microdistortions, calculated by the approximation technique, amount to 8,66 x 10[-4]. The value of energy, stored in the stress-strain state of the crystal lattice of electroexplosive aluminum nanopowder, is 0,385 J/g, while the value of stored energy, determined by means of differential thermal analysis, is 348 J/g. Thus, the most feasible mechanism of storing significant energy in aluminum nanopowder is the formation of more energy-saturated structures in solid (the formation of a double electric layer with pseudocapacity during passivation)