scholarly journals Mechanism of Dy3+ and Nd3+ Ions Electrochemical Coreduction with Ni2+, Co2+, and Fe3+ Ions in Chloride Melts

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7440
Author(s):  
Khasbi Kushkhov ◽  
Zhubagi Ali ◽  
Astemir Khotov ◽  
Anna Kholkina
Keyword(s):  
Intermetallic Compounds ◽  
Cathode Current Density ◽  
Kinetic Regime ◽  
X Ray Diffraction ◽  
Significant Difference ◽  
Cathode Current ◽  
Current Densities ◽  
Electrolysis Potential ◽  
Potentiostatic Regime

The present paper is devoted to the study of the processes of the mechanism of electrochemical coreduction of Dy3+ and Nd3+ ions with Ni2+, Co2+, and Fe3+ ions in the equimolar NaCl-KCl melt at 973 K and characterization of the synthesized samples. The performed voltammetry analysis of the electrochemical coreduction processes elucidated a significant difference in the values of the extraction potentials of the studied metals. This melt testifies that intermetallic compounds of Dy and Nd with Ni, Co, and Fe may be synthesized in the kinetic regime. The intermetallic phases of Dy and Nd with Ni, Co, and Fe are found to be formed along with the phases of metallic Ni, Co, and Fe either during electrolysis at the cathode current densities exceeding the limiting diffusion current of Ni2+, Co2+, and Fe3+ ions or in the potentiostatic regime at the potentials of the corresponding voltammetry curves. Therefore, the following interrelated key parameters affecting the electrochemical synthesis of Dy and Nd intermetallic compounds with Ni, Co, and Fe were determined: (i) composition of the electrolyte, i.e., concentrations of FeCl3, CoCl2, NiCl2, DyCl3, and NdCl3; (ii) cathode current density or electrolysis potential and (iii) electrolysis time. The obtained samples were characterized by micro-X-ray diffraction analysis, cyclic voltammetry, and scanning electron microscopy methods.

The Rotating Cylinder Electrode (RCE) and its Application to the Electrodeposition of Metals

2005 ◽  
Vol 58 (4) ◽  
pp. 246 ◽  
Author(s):  
C. T. John Low ◽  
Carlos Ponce de Leon ◽  
Frank C. Walsh
Keyword(s):  
Rotating Cylinder ◽  
Cathode Current Density ◽  
Vitreous Carbon ◽  
Experimental Investigations ◽  
Rotating Cylinder Electrode ◽  
Expanded Metal ◽  
Cathode Current ◽  
Uniform Current ◽  
Current Densities ◽  
Electrodeposition Of Metals

The application of rotating cylinder electrodes (RCEs) to electrodeposition has progressed significantly over the last decade. New tools for theoretical and experimental investigations have been developed in academia and in industry, with some RCE devices being commercially developed. This paper reviews the continued application of RCEs to quantitative electrodeposition studies of single metals, alloys, and composite, multilayered, and nanostructured electrodeposits with a constant or controlled range of current densities along the RCE under turbulent flow conditions. Rotating cylinder electrode electrochemical reactors, enhanced mass transport, rotating cylinder Hull cell, and uniform and non-uniform current and potential distributions are considered. The applications of ultrasound, porous reticulated vitreous carbon cathodes, expanded metal/baffles, and jet flow around the RCE are also included. The effects of electrolyte flow and cathode current density on electrodeposition have been rationalized. Directions for future RCE studies are proposed.

Microstructure and Growth Mechanism of Glucose-Carburized Nickel Substrates

2013 ◽  
Vol 716 ◽  
pp. 153-158
Author(s):  
E.M. Pechlivani ◽  
G. Stergioudis ◽  
E. Pavlidou ◽  
S. Skolianos ◽  
D. Tsipas
Keyword(s):  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Temperature Treatment ◽  
Effect Of Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treatment Conditions ◽  
Nickel Substrates ◽  
Current Densities

In this research, efforts were made to study the modification of microstructure of pure Ni matrices. Modification was attempted using glucose as carburizing medium under a control of heat treatment conditions. Nickel plates were carburized under vacuum conditions at 380°C and 650°C for 3 hours. In order to determine the parameters of the carburizing, thermal properties of glucose along with the thermochemical behavior were examined by Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). The characterization of the microstructure of the carburized specimens was investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). For analyzing the effect of temperature treatment on corrosion resistance, electrochemical corrosion tests were conducted. It was observed that the polarization curves for carburized samples at 380°C were shifted to lower corrosion current densities. Consequently, lower corrosion rates were achieved for these samples preventing the formation of extensive corrosion over their surfaces comparing with carburized Nickel substrates at 650°C.

scholarly journals Influence of Current Density on the Microstructure of Carbon-Based Cathode Materials during Aluminum Electrolysis

2020 ◽  
Vol 10 (7) ◽  
pp. 2228
Author(s):  
Wei Wang ◽  
Kai Sun
Keyword(s):  
Current Density ◽  
Aluminum Electrolysis ◽  
Cathode Current Density ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Aluminum Reduction ◽  
Electrostatic Charging ◽  
Cathode Current ◽  
Current Densities ◽  
Sodium Expansion

Sodium expansion plays an important role in cathode deterioration during aluminum electrolysis. In this work, the sodium expansion of semigraphitic cathode material has been measured at various cathodic current densities using a modified Rapoport apparatus. We have studied the microstructural changes of carbon cathodes after aluminum electrolysis using high-resolution transmission electron microscopy (HRTEM). Because of an increasing trend toward higher amperage in retrofitted aluminum reduction cells, an investigation is conducted both at a representative cathode current density (0.45 A/cm2) and at a high cathodic current density (0.7 A/cm2). The results indicate that the microstructures of carbon cathodes can be modified by Joule heating and electrostatic charging with higher current densities during aluminum electrolysis. With the penetration of the sodium and melt, zigzag and armchair edges, disordered carbon, and exfoliation of the surface layers may appear in the interior of the carbon cathode. The penetration of the sodium and melt causes remarkable stresses and strains in the carbon cathodes, that gradually result in performance degradation. This shows that increasing the amperage in aluminum reduction cells may exacerbate the material deterioration of the cathodes.

Microstructure Characterization of Multilayered TiSiN/CrN Thin Films

2008 ◽  
Vol 8 (5) ◽  
pp. 2688-2692 ◽  
Author(s):  
Sheng-Min Yang ◽  
Yin-Yu Chang ◽  
Dong-Yih Lin ◽  
Da-Yung Wang ◽  
Weite Wu
Keyword(s):  
Lamellar Structure ◽  
Deposition Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cathodic Arc Deposition ◽  
Cathode Current ◽  
Cathodic Arc ◽  
Crn Coatings ◽  
Arc Deposition

Monolayered TiSiN and multilayered TiSiN/CrN coatings were synthesized by a cathodic arc deposition process. The chromium and Ti/Si (80/20 at.%) alloy targets were adopted as the cathode materials, altering the ratio of cathode current (I[TiSi]/I[Cr]) to obtain various multilayer periodic thicknesses of multilayered TiSiN/CrN coatings. X-ray diffraction and TEM analyses showed that all the deposited monolayered TiSiN and multilayered TiSiN/CrN films possessed the B1-NaCl structure. In this study, it was shown that the multilayer periods (Λ) of the TiSiN/CrN deposited at I[TiSi]/I[Cr] cathode current ratios of 1.8, 1.0, and 0.55 were 8.3 nm, 6.2 nm, and 4.2 nm, respectively, with multilayer periodic thicknesses decreasing with smaller I[TiSi]/I[Cr] cathode current ratios. An amorphous phase was found at the boundaries of the TiN/CrN column grains. In addition, the multilayered TiSiN/CrN coatings displayed a lamellar structure that was well-defined and nonplanar between each TiN and CrN layer.

Preparation of Ti2CuAl5 by Reactive Sintering

1988 ◽  
Vol 133 ◽  
Author(s):  
Arnulf J Maeland ◽  
Dave Narasimhan
Keyword(s):  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Low Temperatures ◽  
Nickel Aluminides ◽  
Reactive Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Process ◽  
Microhardness And Microstructure

ABSTRACTThe exothermic formation of intermetallic compounds from the constituent powders through reactive sintering at relatively low temperatures is a promising new process being explored for the preparation of nickel aluminides. The process is useful for synthesis of other intermetallics as well.We describe here the preparation of Ti2CuAl5 using the technique of reactive sintering. This intermetallic compound has a L12 structure which is also the structure of the very interesting Ni3Al intermetallic. Characterization of the Ti2CuAl5 phase is done by x-ray diffraction, microhardness, and microstructure.

scholarly journals Flexural Strength and Crack Propagation of Porous Clay- Precipitated Calcium Carbonates

2017 ◽  
Author(s):  
NUR ALIA BINTI ROSLIN AZMY
Keyword(s):  
Flexural Strength ◽  
Raw Materials ◽  
Porous Ceramic ◽  
X Ray Diffraction ◽  
Red Clay ◽  
Mineralogical Characterization ◽  
Calcium Carbonates ◽  
Replication Method ◽  
Significant Difference

Porous clay-precipitated calcium carbonates were prepared via polymeric sponge replication method using precipitated calcium carbonates (PCC) and red clay as raw materials. Different compositions of precipitated calcium carbonates (PCC) which is 10 wt.% and 15 wt.% with 24 hours and 48 hours milling time were sintered at 1250°C for 2 hours respectively which influenced the flexural strength and morphology of the porous ceramic. The highest flexural strength (1.843 MPa) were obtained by 10 wt.% [CaCO3]PCC milled at 24 hours related to the lowest percentage of porosity (81.00%). Mineralogical characterization of porous ceramic were determined via X-ray diffraction (XRD) shows the presence of crystalline phases such as anorthite (2CaAl2Si2O8), gehlenite (Ca2Al2SiO7) and esseneite (CaFeAlSiO6) after sintering process. The morphological analysis via stereomicroscope shows that the porosity and struts were found due to presence of precipitated calcium carbonates that act as pore forming agent. The colour of porous ceramic between 10 wt.% [CaCO3]PCC and 15 wt.% [CaCO3]PCC shows significant difference due to iron oxide contained in the red clay which contributes to the colour of the samples. Crack propagates in the intergranular type of fracture mode due to resulted porous ceramic is a brittle material.

scholarly journals Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic

2016 ◽  
Vol 27 (4) ◽  
pp. 468-475 ◽  
Author(s):  
Gabriela Scatimburgo Polli ◽  
Gabriel Rodrigues Hatanaka ◽  
Filipe de Oliveira Abi-Rached ◽  
Lígia Antunes Pereira Pinelli ◽  
Márcio de Sousa Góes ◽  
...  
Keyword(s):  
Fatigue Limit ◽  
Surface Characterization ◽  
Monoclinic Phase ◽  
The Other ◽  
X Ray Diffraction ◽  
Staircase Method ◽  
X Ray ◽  
Significant Difference ◽  
Fracture Area

Abstract This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

Characterization of Ti Alloys Bombarded by keV Deuterium Ions

1992 ◽  
Vol 268 ◽  
Author(s):  
G.P. Chambers ◽  
G. K. Hubler ◽  
J.A. Sprague ◽  
K.S. Grabowski
Keyword(s):  
Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ti Alloys ◽  
Transmission Electron ◽  
Before And After ◽  
Current Densities ◽  
Deuterium Gas ◽  
Secondary Ion

ABSTRACTThin Ti films have been bombarded at room temperature with 350–500 eV deuterium ions at current densities up to 0.5 mA/cm2. Analysis using scanning electron microscopy, x-ray diffraction, transmission electron microscopy, and secondary ion mass spectroscopy were carried out before and after bombardment. It was determined that deuterium diffuses rapidly throughout the Ti film, that the films were in a state of high compressive stress, and that the TiD2 phase was formed. No evidence of deuterium gas bubbles was found.

scholarly journals Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

2011 ◽  
Vol 8 (4) ◽  
pp. 1925-1929 ◽  
Author(s):  
V. S. Protsenko ◽  
V. O Gordiienko ◽  
F. I. Danilov ◽  
S. C. Kwon
Keyword(s):  
Formic Acid ◽  
Current Density ◽  
Nanocrystalline Structure ◽  
Cathode Current Density ◽  
Trivalent Chromium ◽  
Complexing Agents ◽  
Hard Chromium ◽  
Cathode Current

A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

Microstructural Evolution and Corrosion Behavior of Carburized α-Fe Plates by Glucose

2013 ◽  
Vol 203-204 ◽  
pp. 94-98
Author(s):  
Eleftheria Maria Pechlivani ◽  
Fani Stergioudi ◽  
Christos Vogiatzis ◽  
Stefanos Skolianos ◽  
Danuta Stróż
Keyword(s):  
Room Temperature ◽  
Experimental Characterization ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
X Ray ◽  
Electrochemical Tests ◽  
Corrosion Rates ◽  
Current Densities ◽  
Scanning Electron

The aim of this paper is to obtain an experimental characterization of glucose-carburized substrates of α-Fe. The carburization process was achieved under vacuum condition using glucose as a carburizing medium. The process was carried out at several temperatures keeping the duration constant at 2h. The samples were treated at 400°C, 650°C and 900°C. The microstructure of the as produced coatings was observed by Scanning Electron Microscopy (SEM) and the formed phases were analyzed by X-Ray Diffraction (XRD). To investigate the corrosion properties of the carburized iron specimens, electrochemical tests were conducted. The samples were exposed to a solution of 3.5% wt. NaCl electrolyte, under quiescent conditions at room temperature and open to the air. The corroded samples were observed with use of Optical Microscopy in order to evaluate the corrosion effect on their surfaces. Carburization of iron samples at temperatures up to 650°C resulted in a shift of the polarization curves to lower current densities. Smaller corrosion rates were measured indicating higher corrosion resistance for these specimens.

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