Efficiency of Grinding and Mechanical Activation of Solids in Planetary Ball Mills

We develop the algorithm of the procedure for determin-ing the efficiency of operation of planetary mills which is based on the analysis of the movement of the entire load(balls and material) in drums, with the calculation of energy and frequency characteristics of the interaction between milling bodies and material under treatment. We describe the procedure of determination of the efficient power input consumed for driving the ball load of a plane-tary mill and thus for performing the work of grinding and mechanical activation of the material, and some practical examples of industrial applications of planetary-type mills

Mechanochemical Synthesis of Intermetallic Compounds in the System Gallium – Ruthenium

Received: 28.12.2020. Revised: 05.02.2021. Accepted: 05.02.2021. Available online: 08.02.2021.This article belongs to the PCEE-2020 Special Issue.The interaction of a solid inert metal Ru with liquid active metal Ga during mechanical activation in a high-energy planetary ball mill was studied using the X-ray diffraction and the high resolution scanning electron microscopy with energy dispersive X-ray microanalyses. This paper considers mechanical activation effects on formation of intermetallic compounds GaxRuy and their solubility in concentrated acids. Gallium is a surface-active substance with respect to Ruthenium. Under intensive mechanical treatment, liquid Gallium penetrates into grain boundaries of polycrystalline Ruthenium particles and sharply reduces their strength. Because of severe mechanical deformation, an intensive increase of contact surface between solid and liquid metals observed, which a place of rapid formation of intermetallic compounds. This processing leads to high reactive products of mechanical activation of Ga + Ru. Their interaction with a mixed concentrated hydrochloric and nitric acid allows Ruthenium (~37%) to pass into an acidic solution, forming complex compounds of the HxRuCly type (H2RuCl6).The research was carried out within the state assignment to ISSCM SB RAS (project No. 0237-2021-0002)

КОНВЕРСИОННАЯ ХИМИОТЕРАПИЯ В ЛЕЧЕНИИ МЕСТНОРАСПРОСТРАНЕННОГО РАКА ПРЯМОЙ КИШКИ

We present a case report of locally advanced colorectal cancer that responded successfully to conservation chemotherapy allowing R resection to be performed.   Morphological characteristics prior to and after chemotherapy have been described in detail. This case report demonstrates the feasibility of performing radical treatment for patients with locally advanced rectal cancer using neoadjuvant chemotherapy.Представлено клиническое наблюдение успешного применения конверсионной химиотерапии у пациента с местнораспространенным колоректальным раком, которая позволила выполнить оперативное вмешательство R0 у пациента, отнесенного ранее к группе нерезектабельных. Подробно представлены диагностический комплекс и особенности морфологической диагностики до и после химиотерапии. Данное наблюдение демонстрирует возможность проведения радикального лечения больных с местнораспространенным раком прямой кишки с применением неоадъювантной химиотерапии

Механически стимулированные реакции в системах металл–оксид (карбид)

The processes of mechanochemical reduction of oxides of iron, nickel, and copper with aluminum with a stoichio metric ratio of components and in mixtures with a two-, three-, and four-fold excess of the aluminum content over the stoichiometric, as well as in the presence of an excess of oxide-forming metal and solid solutions of aluminum in iron and copper, were studied by the Mössbauer and IR spectroscopy, X-ray diffraction analysis, including the use of synchrotron radiation, and electron microscopy. The conditions for formation of metals modified with aluminum oxide (iron, nickel, copper) and their monoaluminides are determined. High aluminum content aluminides are formed at a three-fold excess of aluminum, and at a four-fold excess, a mechanochemical reduction of oxides does not occur. The preferred method for modifying metals with alumina is the mechanochemical reduction of oxides with a solid solution of aluminum in the oxideforming metal. Mechanochemical interaction in the high-energy Hf–C system in the presence of 20, 30, and 50 wt. % copper leads to the formation of hafnium carbide; and with an increase in the copper content, the crystallite size decreases.Методами мессбауэровской и ИК-спектроскопии, рентгеноструктурного анализа, в том числе с использованием синхротронного излучения, и электронной микроскопии изучены процессы механохимического восстановления оксидов железа, никеля и меди алюминием при стехиометрическом соотношении компонентов и в смесях с двух-, трех- и четырехкратным превышением содержания алюминия над стехиометрическим, а также в присутствии избытка оксидобразующего металла и твердых растворов алюминия в железе и меди. Определены условия, при которых могут быть получены металлы (железо, никель, медь) и их моноалюминиды, модифицированные оксидом алюминия. При трехкратном избытке алюминия формируются алюминиды с большим содержанием алюминия. При четырехкратном увеличении содержания алюминия механохимическое восстановление оксидов не происходит. Предпочтительным способом модифицирования металлов оксидом алюминия является механохимическое восстановление оксидов твердым раствором алюминия в металле, образующем оксид. Методами рентгеновской дифракции и электронной микроскопии изучено механохимическое взаимодействие в высокоэнергетической системе Hf–C в присутствии 20, 30 и 50 мас. % меди. Показано, что с увеличением содержания меди в системе Hf–C–Cu уменьшается размер кристаллитов образующегося карбида гафния

Механохимическое модифицирование оловянных бронз интерметаллидом Cu9 Al4

The influence of the conditions of mechanical activation of a mixture of Cu–12 wt. % Sn with different content of the modifier Cu9 Al4 on the structural-phase composition and morphology of the formed composites was studied by the methods of X-ray diffraction analysis, optical and electron microscopy. With the mechanochemical introduction of 10 wt. % of the modifying additive into the matrix of mechanosynthesized tin bronze, the product mainly forms a ternary solid solution of aluminum and tin in copper, Al0.05Cu0.9Sn0.05. In the case of 20 wt. % of the modifying additive, the product contains a solid solution of tin in copper Cu0.9Sn0.1 and an intermetallic compound Cu9 Al4. Studies of the mechanical and tribotechnical characteristics of the material obtained by sintering under pressure showed that the intensity of wear of bronze of the mechanochemically synthesized powder Cu–12 wt. % Sn is slightly less than that of industrial bronze BrTPh10-1, the friction coefficient f decreases by a factor of 1.4, and the range of its values is quite wide f = 0.7–0.9. Modification of mechanically synthesized Cu–12 wt. % Sn bronze with the Cu9 Al4 intermetallic compound makes it possible to reduce wear by a factor of 1.4–1.8 and significantly reduces the friction coefficient (by a factor of 2). A stable value of f = 0.5 is achieved for the MA composition Cu–12 wt. % Sn + 20 wt. % Cu9 Al4. The introduction of an intermetallic compound increases the microhardness of the alloys by a factor of 1.6–2.0 (up to Hμ = 2730 MPa) relative to the bronze alloy BrTPh10-1and mechanically synthesized bronze.Методами рентгеноструктурного анализа, оптической и электронной микроскопии изучено влияние условий механической активации смеси Cu–12 мас. % Sn с различным содержанием модификатора Cu9 Al4 на структурно-фазовый состав и морфологию формируемых композитов. При механохимическом введении 10 мас. %-ной модифицирующей добавки в матрицу механосинтезированной оловянной бронзы в продукте формируется в основном тройной твердый раствор алюминия и олова в меди, Al0,05Cu0,9Sn0,05. В случае 20 мас. %-ной модифицирующей добавки в продукте присутствуют твердый раствор олова в меди Cu0,9Sn0,1 и интерметаллид Cu9 Al4. Исследования механических и триботехнических характеристик материала, получаемого методом спекания под давлением, показали, что интенсивность изнашивания механохимически синтезированного порошка Cu–12 мас. % Sn незначительно меньше, чем у промышленной бронзы БрОФ 10-1, коэффициент трения f снижается в 1,4 раза, а диапазон разброса его значений достаточно широк f = 0,7–0,9. Модифицирование механосинтезированной бронзы Cu–12 мас. % Sn интерметаллидом Cu9 Al4 позволяет снизить изнашиваемость в 1,4–1,8 раза и значительно снизить коэффициент трения (в 2 раза). Cтабильное значение f = 0,5 достигается для механической активации состава Cu–12 мас. % Sn + + 20 мас. % Cu9 Al4. Введение интерметаллида повышает микротвердость сплавов в 1,6–2,0 раза (до Hμ = 2730 МПа) относительно сплава бронзы БрОФ 10-1 и механосинтезированной бронзы

Chemistry for Sustainable Development 14 (2006) 345353 Nature of a Mechanically Stimulated Phase Change in Zirconia

Abstract Reasons for phase change in zirconia upon its intensive mechanical treatment in mills have been discussed. It has been demonstrated that when used steel balls and barrels, oxidation of wear products and their mechanochemical interaction with ZrO 2 occurs along with a decrease in the size of particles and crystallites. It has been found that implantation of cations of an extrinsic metal in the crystal lattice is favourable to the stabilization of a more symmetric modification and to an increase in the critical size of crystallites, above which the monoclinic modification becomes stable. A conclusion has been made that an increase in the contribution of superficial energy to the Gibbs energy plays domin ating part in the phase change on initial stages of mechanical treatment, while the thermodyn amic stability in the further process is controlled preferentially by a stabilising impact of impurity cations. Under conditions that prevent from pollution of ZrO 2 by metal, a dyn amic equilibrium is established between the forward change to tetragon al modification and the reverse, to monoclinic

Chemistry for Sustainable Development 20 (2012) 351359 Modelling of X-ray Diffraction Patterns from Nanostructured Perovskites Sr(Fe,Co)Î 3 δ δ δ δ δ

Abstract (2.5 < (3 δ) < 2.7) are considered. Diffraction patterns of a number of samples differing in cation composition and degree of nonstoichiometry exhibit intensive reflections that are characteristic of the perovskite structural type with weak wider superstructural peaks. It is demonstrated by means of computer modelling of X-ray scattering on the crystals with different defects that such a diffraction pattern can correspond to three models of ordering of the oxygen vacancies: the formation of a homogeneous structure with the ordered state of oxygen vacancies (structural elements of the low-symmetry phase) and the formation of n anoheterogeneous systems (brownmillerite ABO 2.5 + perovskite ABO 3 ) of two types. In the first case, the components of the system have lamellar shape and interchange in one direction (a unidimension al disorder). In the second case we speak of the structure of brownmillerite domains turned with respect to each other at an angle of 90°, with different methods of redistribution of the perovskite component at interfaces or in the form of separate domains. It is demonstrated with the help of two-dimensional diffraction of X-rays that this texture is observed not only at the nano-level but also for the samples with microdomains

Chemistry for Sustainable Development 19 (2011) 447455 Mechanochemical Interaction of Silicon Dioxide with Organic Acids

Abstract The interaction of amorphous silicon oxide (aerosil) with organic acids during mechanical activation in high-energy ball mill was studied by means of IR spectroscopy. It was demonstrated that monomer molecules of mono-, polyhydric and aromatic acids get bound with aerosil through the molecules of adsorbed water: aerosiladsorbed wateracid. Water molecules form rather strong hydrogen bonds with the basic surface centres in aerosil and with hydroxyls of carboxylic groups in monomer molecules of acids. Both basic and acidic surface centres of the carrier take part in the mechanochemical interaction with aerosil