Texture Evolution along the Layer Thickness in a Fe-3%Si Steel under Electropulsing Treatment

2011 ◽  
Vol 702-703 ◽  
pp. 943-946 ◽  
Author(s):  
Xin Li Wang ◽  
Hong Ming Zhao ◽  
Wen Bin Dai ◽  
Xiang Zhao
Keyword(s):  
Layer Thickness ◽  
Current Density ◽  
High Current Density ◽  
Texture Evolution ◽  
Specimen Thickness ◽  
Evolution Analysis ◽  
Orientation Density ◽  
Current Densities ◽  
The Difference ◽  
Electropulsing Treatment

Effects of electric current densities on recrystallization texture evolution in cold-rolled Fe-3%Si steel were investigated by using a high current density electropulsing treatment. Results showed that the orientation density of α fiber and  fiber varied with the specimen thickness during current passing. However, with the current density increasing, the difference from layer thickness almost vanished. In addition, Goss component texture was the final sharper one but no relation with the specimen thickness at 9.96kAmm-2. By the texture evolution analysis, it was found that the preferred nucleation always occurred in the surface layer due to the high storied energy coursed by previous cold rolling. Combined with the corresponding microstructures, it could be found that though there was an apparent texture evolution along specimen thickness, the microstructure had no change with thickness. In addition, due to the application of electropulsing, the recrystallization nucleation was greatly increased.

Polyaniline: Influence of Polymerization Current Density

1994 ◽  
Vol 369 ◽  
Author(s):  
Steen Skaarup ◽  
L.M.W.K. Gunaratne ◽  
Keld West ◽  
Birgit Zachau-Christiansen
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
High Current Density ◽  
Electrochemical Polymerization ◽  
Regular Structure ◽  
Spectral Lines ◽  
Complex Nature ◽  
Cyclic Voltammograms ◽  
Layer By Layer ◽  
Current Densities

AbstractPolyaniline has been synthesized in propylene carbonate by galvanostatic electrochemical polymerization at current densities between 16 and 1000 μA/cm2. Earlier results for polypyrrole have shown that low and high current density films have different properties: The films synthesized at low current density have a higher conjugation length and a more regular structure. The corresponding effect in PANI has been investigated by cyclic voltammetry and UV/visible spectroscopy. Simultaneous measurement of cyclic voltammograms and the absorbtion of selected spectral lines is used because of the complex nature of the PANI system which involves several redox systems as well as forms differing in the degree of protonation and morphology.The main result is that the method of galvanostatic synthesis at low current densities (-16 μA/cm2) produces polyaniline polymers of different, more conjugated and more regular structure than those prepared at higher current densities. The standard method of in situ layer-by-layer polymerization of conducting polymers during cyclic voltammetry often results in uncontrolled and unmeasured current densities of 0.5-2 mA/cm2 which produces a film that probably has a less regular structure containing more deviations from ideality.

scholarly journals Unexpected Genomic Features of High Current Density-Producing Geobacter sulfurreducens strain YM18

2021 ◽  
Author(s):  
Takashi Fujikawa ◽  
Yoshitoshi Ogura ◽  
Koki Ishigami ◽  
Yoshihiro Kawano ◽  
Miyuki Nagamine ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Current Density ◽  
Iron Reduction ◽  
High Current Density ◽  
Model Organism ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
High Current ◽  
Current Production ◽  
Current Densities

Abstract Geobacter sulfurreducens produces high current densities and it has been used as a model organism for extracellular electron transfer studies. Nine G. sulfurreducens strains were isolated from biofilms formed on an anode poised at –0.2 V (vs. SHE) in a bioelectrochemical system in which river sediment was used as an inoculum. The maximum current density of an isolate, strain YM18 (9.29 A/m2), was higher than that of the strains PCA (5.72 A/m2), the type strain of G. sulfurreducens, and comparable to strain KN400 (8.38 A/m2), which is another high current producing strain of G. sulfurreducens. Genomic comparison of strains PCA, KN400, and YM18 revealed that omcB, xapD, spc, and ompJ, which are known to be important genes for iron reduction and current production in PCA, were not present in YM18. In the PCA and KN400 genomes, two and one region (s) encoding CRISPR/Cas systems were identified, respectively, but they were missing in the YM18 genome. These results indicate that there is genetic variation in the key components involved in extracellular electron transfer among G. sulfurreducens strains.

scholarly journals Impact of microarc carburizing and boriding of steel on diffusion layer structure

2021 ◽  
Vol 63 (11-12) ◽  
pp. 929-934
Author(s):  
Yu. M. Dombrovskii ◽  
M. S. Stepanov
Keyword(s):  
Layer Thickness ◽  
Diffusion Layer ◽  
Current Density ◽  
Steel Surface ◽  
Layer Structure ◽  
Heating Temperature ◽  
High Current Density ◽  
Original Structure ◽  
Heterogeneous Structure ◽  
Coal Particles

Intensification of carburizing and boriding of steel parts is achieved by microarc surface alloying. For carburizing, the parts are immersed in coal powder followed by electric current passing. For boriding, a coating with diffusant is used. Acceleration of diffusion is achieved by action of microarc discharges on the steel surface. The aim of this work was to study the effect of diffusion parameters on thickness, structure, and phase composition of coatings. The samples were made of 20 steel. Surface current density was 0.45 – 0.53 A/cm2. Duration of the process was 2 – 8 min. At the beginning of heating, temperature of the samples increases, and then stabilizes at 930 – 1250 °C due to cessation of micro-formation during combustion of coal particles. After carburizing, a eutectoid mixture is formed on the surface, then, the zone with ferrite-perlite structure is located, which transfers into the original structure. The maximum layer thickness (60 – 390 microns) is reached after 6 – 7 min of heating and then does not increase due to a decrease in the carbon potential during combustion of coal particles. Similar relationship is obtained when boriding: the maximum layer thickness (60 – 340 microns) is reached after 6 – 7 min and then does not increase due to depletion of diffusant source in the coating. At current density of 0.45 A/cm2, the layer consists of a base (a dispersed ferrite-carbide mixture) containing fine inclusions of iron borides and boron carbide. At current densities of 0.49 and 0.53 A/cm2, the layer has heterogeneous structure, with areas of high-hard boride eutectic located at the base. At high current density, diffusion of carbon and boron along the grain boundaries forms Fe – C – B triple eutectic. At lower current density, surface temperature is lower than eutectic formation temperature, so heterogeneous coating structure is not formed. The work results make it possible to choose modes of microarc heating to obtain the required parameters of diffusion layer.

Selective Conversion of Carbon Dioxide to Formate with High Current Densities

2021 ◽  
pp. 2150001
Author(s):  
Xiulin Yang ◽  
Defei Liu ◽  
Shenghong Zhong ◽  
Xiaofeng Zhou ◽  
Kuo-Wei Huang ◽  
...  
Keyword(s):  
Current Density ◽  
Hollow Fiber ◽  
Active Sites ◽  
Large Scale ◽  
High Current Density ◽  
High Current ◽  
Faradaic Efficiency ◽  
Practical Applications ◽  
Selective Conversion ◽  
Current Densities

Selective conversion of CO2 to formate with high current densities is highly desirable but still challenging. Copper hollow fibers with interconnected pore structures were fabricated via a facile method and used as a stand-alone cathode for highly efficient electrochemical reduction of CO2 to formate. Our studies revealed that delivering the reactant CO2 gas to the inner space of the hollow fiber could build up a higher CO2 partial pressure in the pores and presumably reduce the concentration of H[Formula: see text] from the electrolyte to effectively suppress the major competing reaction, hydrogen evolution reaction (HER), from 46.9% faradaic efficiency (FE) to 15.0%. A high selectivity for CO2 reduction to formate with a maximum FE of 77.1% was achieved with a high current density of 34.7[Formula: see text]mA cm[Formula: see text], which is one of the highest FEs on Cu-based materials. Mechanistic studies suggest that the abundant active sites along with the unique crystal facets induced by the high pressure of CO2 at the pore surface in the “gas in” mode are attributed to the superior electroactivity and selectivity for the CO2 reduction to formate. The Cu hollow fiber electrodes exhibit an outstanding long-term stability at high current density, showing great potential for large-scale practical applications.

scholarly journals The spectrum of carbon arcs in air at high current densities

1927 ◽  
Vol 117 (776) ◽  
pp. 164-182 ◽  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Short Note ◽  
Direct Vision ◽  
Ground Glass ◽  
Total Radiation ◽  
High Current ◽  
Carbon Arc ◽  
Current Densities ◽  
Made In

Although the spectrum of the ordinary carbon arc has been studied in great detail during the last 70 years, there seems to have been no similar study of the “High Current Density” arc which was introduced by Beck in 1914. Spectrophotometrical measurements have been made in connection with the development of this type of arc for searchlights, and photographs of the spectra obtained from the total radiation from the arc have been published. The only account, however, of the spectrum from individual parts of the arc appears in a short note by Bell and Bassett. They examined an image of the arc on a ground glass screen with a direct vision spectroscope and reported that in the arc stream 15 lines appeared when the current exceeded 100 amperes. They attributed 7 of these to helium and 2 to hydrogen.

Formation of nanophases in a Cu–Zn alloy under high current density electropulsing

2000 ◽  
Vol 15 (10) ◽  
pp. 2065-2068 ◽  
Author(s):  
W. Zhang ◽  
M. L. Sui ◽  
K. Y. Hu ◽  
D. X. Li ◽  
X. N. Guo ◽  
...  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
High Energy ◽  
Coarse Grained ◽  
High Current ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Before And After ◽  
Electropulsing Treatment ◽  
Zn Alloy

The microstructure of samples before and after a high current density electropulsing treatment was characterized by using high-resolution transmission electron microscopy. It has been found that in the coarse-grained Cu–Zn alloy subjected to the electropulsing treatment, two nanophases were formed, α–Cu(Zn) and β′–(CuZn), the average grain size of which is about 11 nm. A possible mechanism for the formation of nanophases was proposed. The experimental results indicated that electropulsing, as an instantaneous high-energy input, plays an important role in the nonequilibrium microstructural changes in materials and serves as a potential processing approach to synthesize nanostructured materials.

Texture and Microstructural Evolution under Electric Current Pulses in a Fe-3%Si Steel

2011 ◽  
Vol 197-198 ◽  
pp. 1104-1108 ◽  
Author(s):  
Xin Li Wang ◽  
Hong Ming Zhao ◽  
Wen Bin Dai ◽  
Xiang Zhao
Keyword(s):  
Electric Current ◽  
Microstructural Evolution ◽  
Current Density ◽  
High Current Density ◽  
Current Direction ◽  
Direction Parallel ◽  
Current Pulses ◽  
Electric Current Pulses ◽  
Current Densities ◽  
Cold Rolled

The evolution of the recrystallization texture under high current density electric current pulses (ECP) was investigated in a cold-rolled Fe-3%Si steel sheet. Results showed that the preferred nucleation always occurred in the direction parallel to the current direction at the primary stage of recrytallization. With the increment of the current density, the effect of current direction on texture and microstructural evolution was decreased. Due to the different texture component along the layer depth under different current densities, it was also found that the recrystallization nucleation was much easier to occur from the top surface.

Layer-structured FeCo bihydroxide as an ultra-stable bifunctional electrocatalyst for water splitting at high current densities

2021 ◽  
Author(s):  
Chaoyang Sun ◽  
Hui Wang ◽  
Shan Ji ◽  
Xuyun Wang ◽  
Vladimir Linkov ◽  
...  
Keyword(s):  
Water Splitting ◽  
Current Density ◽  
High Stability ◽  
High Current Density ◽  
High Current ◽  
Bifunctional Electrocatalyst ◽  
Current Densities ◽  
Double Hydroxide

A layered FeCo double hydroxide bifunctional water cracking electrocatalyst with ultra-high stability at high current density was developed.

Formation of a Nanostructure in a Low-carbon Steel Under High Current Density Electropulsing

2002 ◽  
Vol 17 (5) ◽  
pp. 921-924 ◽  
Author(s):  
Yizhou Zhou ◽  
Wei Zhang ◽  
Manling Sui ◽  
Douxing Li ◽  
Guanhu He ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Current Density ◽  
High Current Density ◽  
Low Carbon Steel ◽  
Coarse Grained ◽  
High Current ◽  
Low Carbon ◽  
Crystalline Materials ◽  
Transmission Electron ◽  
Electropulsing Treatment

The microstructure of a low-carbon steel after high current density electropulsing treatment was characterized by high-resolution transmission electron microscopy. It was found that nanostructured γ-Fe could be formed in the coarse-grained steel after the electropulsing treatment. The mechanism of the formation of a nanostructure was discussed. It was thought that change of the thermodynamic barrier during phase transformation under electropulsing was a factor that cannot be neglected. It was reasonable to anticipate that a new method might be developed to produce nanostructured materials directly from the conventional coarse-grained crystalline materials by applying high current density electropulsing.

Effects of Electropulsing Treatment on the Precipitation Behaviour of Grain Boundary Carbides in GH3044 Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 464-467 ◽  
Author(s):  
Yang Liu ◽  
Lei Wang ◽  
Yu Chen Wang ◽  
Hong Yan Liu ◽  
Xue Jiao Chen ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Current Density ◽  
Pulse Width ◽  
High Current Density ◽  
Aging Treatment ◽  
Volume Percentage ◽  
Precipitation Behaviour ◽  
M23c6 Type ◽  
Type Carbide ◽  
Electropulsing Treatment

The effects of electropulsing treatment on the precipitation behaviour of grain boundary carbides in GH3044 alloy were investigated. The results showed that the initial temperature of precipitation of M23C6 type carbides on grain boundary could be decreased by electropulsing treatment under the condition of high current density of 10.0kA/mm2 with a frequency of 5Hz and pulse width of 15s. The volume percentage of M23C6 type carbide was greatly increased to 274.60% comparing with that of the aging treatment at the same temperature. However, the precipitation of M23C6 type carbide was inhibited by electropulsing treatment under the condition of high frequency of 45Hz with the current density of 2kA/mm2 and pulse width of 15s. The volume percentage of M23C6 type carbide was decreased to 18.81% comparing with that of the aging treatment at the same temperature. It has been found that the diffusion of solute atom in the alloy can be promoted by the electric effect with the electropulsing. As a result, the thermodynamic condition and kinetics of the precipitation of M23C6 type carbide were changed, and both the initial and peak temperatures of precipitation were decreased.

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