scholarly journals ELECTROCHEMICAL SYNTHESIS OF TUNGSTEN OXIDE BRONZE POWDERS

2020 ◽  
pp. 738-745
Author(s):  
Борис Магометович Хуболов
Keyword(s):  
Grain Size ◽  
Chemical Analysis ◽  
Alkali Metal ◽  
Tungsten Oxide ◽  
Electrochemical Synthesis ◽  
Cathode Current Density ◽  
Melt Temperature ◽  
Oxide Bronze ◽  
Oxide Bronzes ◽  
Cathode Current

Химическим анализом установлено, что при электрохимическом восстановлении в расплавах MWO -WO (M - Li, Na, K, Cs,Tl) образуются оксидные вольфрамовые бронзы различного состава и структуры. Изучена зависимость изменения равновесных потенциалов катодных продуктов от температуры и состава расплава. Установлено, что с увеличением содержания щелочного металла в вольфраматных расплавах число зародышей кристаллов уменьшается. Снижение температуры расплава и увеличение катодной плотности тока также приводит к уменьшению размеров зерен катодных осадков, что позволяет получать порошки оксидных вольфрамовых бронз контролируемой дисперсности. Методами рентгеноэлектронной спектроскопии и каналирования были исследованы структура конденсированных в среднем вакууме тонких пленок, а также монокристаллы натрийвольфрамовых бронз электрохимически циклированных в анодном и катодном режимах для получения информации о толщине окрашивающего слоя. Chemical analysis established that during electrochemical reduction in MWO - WO (M - Li, Na, K, Cs,Tl) melts, tungsten oxide bronzes of various compositions and structures are formed. The dependence of the change in the equilibrium potentials of cathode products on the temperature and composition of the melt has been studied. It was found that with an increase in the content of alkali metal in tungsten melts, the number of crystal nuclei decreases. A decrease in the melt temperature and an increase in the cathode current density also lead to a decrease in the grain size of the cathode deposits, which makes it possible to obtain powders of tungsten oxide bronzes of controlled dispersion.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Bituminous Insulations Durability of Underground Metallic Pipelines I Field investigations

2017 ◽  
Vol 68 (3) ◽  
pp. 581-585 ◽  
Author(s):  
Gabriela Oprina ◽  
Ladislau Radermacher ◽  
Daniel Lingvay ◽  
Dorian Marin ◽  
Andreea Voina ◽  
...  
Keyword(s):  
Cathode Current Density ◽  
Induced Voltage ◽  
Cathodic Current ◽  
Field Investigations ◽  
Operation Period ◽  
Cathode Current ◽  
Protection Potential ◽  
Cathodic Protection System ◽  
Corrosion State ◽  
Good Agreement

The corrosion state of an underground metallic pipeline of �161 mm and 565 m length was assessed by specific electrical and electrochemical measurements. The investigated pipe, buried in 1997, was protected against corrosion by successive layers of bituminous material with a total thickness of 1 to 1.2 mm. The pipeline crosses three electrified railway lines (50 Hz - 28 kV), and then its route is approximately parallel to these lines; thus, the induced AC voltages between line and ground were calculated obtaining values between 4.05 and 7.1 Vrms, in good agreement with the values measured in the accessible points. The measurements regarding the insulation capacity against corrosion of the bituminous insulation, performed at one month and after 19 years of burial, showed an increase of the average cathode current density needed for obtaining the protection potential in the range �1.00 � �1.28 VCu/CuSO4 of approx. three times (from 6.65 up to 19.96 mA/m2), in good agreement with the evolution of the insulation resistance measured between the steel pipe (having a contact area with the ground of 270.5 m2) and a ground socket of 4 W, which decreased from 995 to 315 kW. Following the analysis and processing of the field collected data, it is considered that, by implementing a cheap cathodic protection system (without cathodic current power supply), based on the rectification of the AC induced voltage, the safe operation period of the investigated pipeline may be extended by at least 50 years.

RESTORATION OF MACHINE PARTS WITH GALVANIZED ZINC COATINGS

2020 ◽  
Vol 4 (141) ◽  
pp. 140-147
Author(s):  
MIKHAIL VIKHAREV ◽  
◽  
VLADIMIR YUDIN ◽  
VESELOVSKIY NIKOLAY ◽  
◽  
...  
Keyword(s):  
Current Density ◽  
Cathode Surface ◽  
Zinc Coating ◽  
Cathode Current Density ◽  
Research Purpose ◽  
Cathode Layer ◽  
Properties Of Coatings ◽  
Chemical Polarization ◽  
Cathode Current ◽  
Zinc Coatings

The article shows the role of electroplating in the restoration of parts, indicates the advantages of restoring parts with electroplating over other methods, and gives the characteristics and properties of coatings obtained by electroplating. (Research purpose) The research purpose is in increasing the speed of application of zinc electroplating when restoring parts. (Materials and methods) The cathode current density has a decisive influence on the coating speed. The main reason for limiting the cathode current density during galvanizing from sulfuric acid electrolytes is the chemical polarization of the cathode. The article presents a study on the designed installation for the application of galvanic coatings. When applying coatings to the internal surfaces of parts, there was used a device with activating elements having an electromechanical rotation drive. This device prevents depletion of the near-cathode layer of the electrolyte and reduces the chemical polarization of the cathode. Elements made of moisture-resistant skin were used as activators. (Results and discussion) The article presents the results of experiments as a dependence of the coating speed on the speed of the activator relative to the restoring surface. It also presents the relationship between the size of the abrasive grains of the activating elements, the force of their pressing against the cathode surface, the speed of movement of the activator and the speed of applying the zinc coating, as well as its quality. By activating the cathode surface, it was possible to raise the operating current density to 100-150 amperes per square decimeter. The speed of application of zinc coatings is 16-25 micrometers per minute. (Conclusions) In the course of research, authors determined the conditions of electrolysis during galvanizing, which provide a significant increase in the cathode current density and the rate of application of these coatings during the restoration of parts.

scholarly journals Cathodic protection of structures in seawater using solar panels

2019 ◽  
Vol 121 ◽  
pp. 02004
Author(s):  
Boris Borisovich Chernov ◽  
Van Mung Vu ◽  
Anac Maskharovich Nugmanov ◽  
Lyudmila Yuryevna Firsova
Keyword(s):  
Cathodic Protection ◽  
Sea Water ◽  
Cathode Current Density ◽  
Complete Agreement ◽  
Low Alloy Steels ◽  
Solar Panels ◽  
Protective Properties ◽  
Theoretical Concepts ◽  
Alloy Steels ◽  
Cathode Current

It is well known that the cathodic protection of structures in seawater is accompanied by the formation of calcareous deposits on them. In current study, we consider the physicochemical modelling of the formation of the deposit composition against cathode current density in seawater. The reliability of the model representations is confirmed by direct experiments. The work also studied the protective properties of the deposits with a different composition for low-alloy steels in natural sea water. It has been shown that the deposits of pure Mg(OH)2 and the deposits of CaCO3 + Mg(OH)2 had better protective ability against corrosion than the deposits of pure CaCO3. However, the deposits of Mg(OH)2 dissolved faster than the deposits of CaCO3 and CaCO3 + Mg(OH)2. Theoretical concepts and experiments on the laws governing the formation of the deposits and their protective properties are in complete agreement with each other. This allows to use the obtained patterns in the cathodic protection of structures in sea water using solar panels, forming standard deviations with predetermined protective properties in the daytime.

Ionization parameters of some nitro compounds on the surface of alkali metal oxide bronze

2004 ◽  
Vol 30 (9) ◽  
pp. 717-718 ◽  
Author(s):  
V. I. Kapustin ◽  
V. S. Petrov ◽  
A. A. Chernousov
Keyword(s):  
Alkali Metal ◽  
Metal Oxide ◽  
Nitro Compounds ◽  
Alkali Metal Oxide ◽  
Oxide Bronze

scholarly journals SEDIMENTOLOGIA DE LAGUNAS COSTERAS: CIENAGA GRANDE DE SANTA MARTA Y CIENAGA DE PAJARALES

2016 ◽  
Vol 25 ◽  
Author(s):  
Gladys Bernal ◽  
Julliet Betancur
Keyword(s):  
Grain Size ◽  
Organic Matter ◽  
Chemical Analysis ◽  
X Ray Diffraction ◽  
Caribbean Coast ◽  
X Ray ◽  
Deltaic Plain ◽  
Magdalena River

Ciénaga Grande de Santa Marta and Ciénaga de Pajarales are the two main lagoons of the marginal lagunar system at the deltaic floodplain of Magdalena river, Caribbean coast of Colombia. A systematic surficial sampling was carried out in such lagoons and Salamanca coast. A sporadic sampling was done in other places of the deltaic plain. This paper presents results about grain size, mineralogy, organic matter contents, CaCOa contents, X ray diffraction and chemical analysis of salts for sediments. Sedimentologic charts, distribution schemes and provenience notes are presented.

Alkali Metal Titanium Oxide Bronzes

Nature ◽  
1961 ◽  
Vol 192 (4802) ◽  
pp. 551-552 ◽  
Author(s):  
A. D. WADSLEY ◽  
STEN ANDERSSON
Keyword(s):  
Alkali Metal ◽  
Titanium Oxide ◽  
Oxide Bronzes ◽  
Metal Titanium

scholarly journals Quantitative approach to realization of ultrasonic grain refinement of Al-7Si-2Cu-1Mg alloy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Soo-Bae Kim ◽  
Young-Hee Cho ◽  
Min-Su Jo ◽  
Jae-Gil Jung ◽  
Young-Kook Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Refinement ◽  
Particle Diameter ◽  
Nucleation Site ◽  
Melt Temperature ◽  
Transmission Electron ◽  
Refinement Mechanism ◽  
Ultrasonic Melt Treatment ◽  
The Relationship

AbstractUltrasonic melt treatment (UST) was applied to Al-7Si-2Cu-1Mg melt at various temperatures of 620, 650, 700 and 785 °C. MgAl2O4 particles which were often found to be densely populated along oxide films, became effectively dispersed and well-wetted by UST. Transmission electron microscopy work combined with crystallography analysis clearly indicates that MgAl2O4 particles can act as α-Al nucleation site with the aid of UST. However, with UST, grain refinement occurred only at temperature of 620 °C and the grain size increased from 97 to 351 μm with increase of melt temperature to 785 °C for UST. In quantitative analysis of grain size and MgAl2O4 particle diameter, it was found that ultrasonic de-agglomeration decreased mean particle size of the MgAl2O4 particles, significantly reducing size from 1.2 to 0.4 μm when temperature increased from 620 to 785 °C. Such a size reduction with increased number of MgAl2O4 particles does not always guarantee grain refinement. Thus, in this work, detailed condition for achieving grain refinement by UST is discussed based on quantitative measurement. Furthermore, we tried to suggest the most valid grain refinement mechanism among the known mechanisms by investigation of the relationship between grain size and particle size with variation of melt temperature.

scholarly journals Effect of Melt Temperature on the Effectiveness of the Grain Refining in Al-Si Castings

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
A. M. Samuel ◽  
S. S. Mohamed ◽  
H. W. Doty ◽  
S. Valtierra ◽  
F. H. Samuel
Keyword(s):  
Grain Size ◽  
Dendritic Structure ◽  
Grain Refining ◽  
Liquid Temperature ◽  
Grain Refiner ◽  
Dendrite Morphology ◽  
Melt Temperature ◽  
Strong Affinity ◽  
Rounded Form ◽  
Molten Liquid

The results inferred from the present work show that Al3Ti phase has a strong affinity to react with silicon (Si) in the molten alloy leading to formation of (Al,Si)3Ti phase instead. This reaction is independent of the grain refiner type. The molten liquid temperature would change its morphology from platelets at 750°C into dendritic structure at 950°C. It has also been observed that (Al,Si)3Ti phase platelets precipitate within the α-aluminum dendrites, whereas TiB2 or AlB2 particles are released into the surrounding interdendritic regions. Introduction of the grain refiner, regardless its type, would cause change in the α-aluminum dendrite morphology from an elongated to a more rounded form. The results also reveal that addition of 100 ppm B will reduce the initial grain size by ∼85% which is more than the effect of addition of 0.2%Ti in the form of Al-10%Ti (about 65%). Elimination of undercooling is important to obtain the maximum grain refining effect.

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