Composition of powders produced by electrospark dispersion of metal granules in water

The results of experimental studies of metal powders composition produced by electrospark dispersion according to the scheme "metal electrodes - metal granule loading - distilled water" are given in the paper. With a help of X-ray diffraction analysis and other methods, it was found that chemical and phase composition of dispersion products is determined by affinity of metal to oxygen

Thermocatalytic conversion of petroleum paraffin in the presence of tungsten carbide powders

Russia occupies the third place in the world in terms of stocks of heavy oil raw materials. The development of deposits of light and medium oils makes it inevitable to involve heavy, as well as residual, petroleum raw materials in processing to meet the growing demand for petroleum products. Increase of the depth of oil processing possible in various ways, one of which is the use of new efficient catalysts, resistant to corrosion, poisoning and coking. Tungsten carbide, meeting these requirements, is a promising starting compound for the production of cracking catalysts for heavy oil feedstocks. The influence of tungsten carbide and its calcination temperature on the composition and yield of oil paraffin cracking products on the resulting catalysts was studied to investigate its catalytic activity, the optimum treatment temperature of tungsten carbide was determined. The high catalytic activity of a WC sample calcined at 420°C is shown. Using the physicochemical methods of investigation, the properties of tungsten carbide samples, as well as the composition and properties of the paraffin cracking products in the presence of the catalysts obtained, were studied

Investigation of oxidation process of mechanically activated ultrafine iron powders

The oxidation of mechanically activated ultrafine iron powders was studied using X-ray powder diffraction and thermogravimetric analyzes. The powders with average particles size of 100 nm were made by the electric explosion of wire, and were subjected to mechanical activation in planetary ball mill for 15 and 40 minutes. It was shown that a certain amount of FeO phase is formed during mechanical activation of ultrafine iron powders. According to thermogravimetric analysis, the oxidation process of non-milled ultrafine iron powders is a complex process and occurs in three stages. The preliminary mechanical activation of powders considerably changes the nature of the iron powders oxidation, leads to increasing in the temperature of oxidation onset and shifts the reaction to higher temperatures. For the milled powders, the oxidation is more simple process and occurs in a single step

ИЗУЧЕНИЕ СВОЙСТВ ТОНКОДИСПЕРСНЫХ ЧАСТИЦ, ПОЛУЧЕННЫХ ПРИ ДИСПЕРГИРОВАНИИ ТВЕРДОГО СПЛАВА ВК6 ЭЛЕКТРОИМПУЛЬСНЫМ МЕТОДОМ

 Properties of WC–6Co hard alloy powders obtained by the method of spark plasma dispersion (SPD) are presemed. Powders of WC–6Co hard alloy were produced using spark erosion in distilled water. The properties of powders, such as specific surface area, morphology, structure and size distribution, were studied. Investigation of the powder properties was made using the methods of scanning electron microscopy, X-ray phase analysis and disk centrifugal sedimentation particle size analysis. The principal possibility of SPD method to produce highly active additives, suitable to use during creation of tools and hardening of wear-resistant coatings from hard alloy waste is shown. В работе представлены результаты электроискрового диспергирования (ЭИД) стружки из сплава ВК6 в воде. Приведены величины удельной поверхности, морфологии, структуры и распределения частиц в порошках по размерам. Для исследования свойств использовали дисковый центробежный седиментационный анализатор размера частиц, методы растровой электронной микроскопии и рентгенофазового анализа. Показана принципиальная возможность применения ЭИД для изготовления тонкодисперсных порошков из отходов твердого сплава, пригодных для повторного использования в качестве высокоактивных добавок при создании инструмента и получении износостойких упрочняющих покрытий.

Preliminary results from the CMD-2 detector

A new general-purpose detector CMD-2 (calorimetric magnetic detector has started experiments at the upgraded e{sup {plus}}e{sup {minus}} collider VEPP-2M (collider for electron-positron beams) at Novosibirsk. During early runs an integrated luminosity of about 400 inverse nanobarns has been collected in the center of mass energy range 400{endash}1030 MeV

Determination of uranium concentration and burn-up of irradiated reactor fuel in contaminated areas in Belarus using uranium isotopic ratios in soil samples

An analytical method is described for the estimation of uranium concentrations, of U-235/U-238 and U-236/U-238 isotope ratios and burn-up of irradiated reactor uranium in contaminated soil samples by inductively coupled plasma mass spectrometry. Experimental results obtained at 12 sampling sites situated on northern and western radioactive fallout tails 4 to 53 km distant from Chernobyl nuclear power plant (NPP) are presented. Concentrations of irradiated uranium in the upper 0-10cm soil layers at the investigated sampling sites varied from 2.1 x 10(-9) g/g to 2.0 x 10(-6) /g depending mainly on the distance from Chernobyl NPP. A slight variation of the degree of burn-up of spent reactor uranium was revealed by analyzing U-235/U-238 U and U-236/U-211 isotope ratios and the average value amounted to 9.4 +/- 0.3 MWd/(kg, U)

Composition of powders produced by electrospark dispersion of metal granules in water

The results of experimental studies of metal powders composition produced by electrospark dispersion according to the scheme "metal electrodes - metal granule loading - distilled water" are given in the paper. With a help of X-ray diffraction analysis and other methods, it was found that chemical and phase composition of dispersion products is determined by affinity of metal to oxygen