Effect of Different Ca Content on Microstructure and Electrochemical Performance of As-Cast AZ31 Magnesium Alloy Sacrificial Anodes

2013 ◽  
Vol 431 ◽  
pp. 42-47
Author(s):  
Hong Wei Cui ◽  
Ting Bin Li ◽  
Xiao Hong Du ◽  
Hong Wei Ding ◽  
Guang Hui Min
Keyword(s):  
Electrochemical Performance ◽  
Grain Refinement ◽  
Open Circuit Potential ◽  
Volume Fraction ◽  
Open Circuit ◽  
Sacrificial Anodes ◽  
Effective Current ◽  
Marketing Application ◽  
Ca Addition ◽  
Second Phases

The effect of ca on the as-cast microstructure and electrochemical performance of AZ31 anode was investigated. The results show that addition of Ca to AZ31 anodes can result in not only grain refinement, but also a change in both morphology and volume fraction of the second phases. And grain refinement by Ca addition can be explained by the GRF mechanism. 0.4%Ca addition to as-cast AZ31 anode can increase the effective current capacity and current efficiency, and meet the requirements of magnesium sacrificial anode, but open circuit potential is lower than the nation standards. AZ31-0.4Ca anode will have a broad marketing application prospect.

scholarly journals Effects of Repetitive Upsetting Extrusion on the Microstructure and Texture of GWZK124 Alloy under Different Starting Temperatures

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2437
Author(s):  
Guanshi Zhang ◽  
Zhimin Zhang ◽  
Yingze Meng ◽  
Zhaoming Yan ◽  
Xin Che ◽  
...  
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Volume Fraction ◽  
Bimodal Microstructure ◽  
Continuous Dynamic Recrystallization ◽  
Average Grain Size ◽  
Second Phases ◽  
Continuous Dynamic ◽  
Weak Texture

The effects of repetitive upsetting extrusion under different starting temperatures on the microstructure and texture of GWZK124 alloy were investigated. The results clearly showed that the particles and second phases induced dynamic recrystallization (DRX), which can be explained by the particle-stimulated nucleation (PSN) mechanism. It was shown that grain refinement during repetitive upsetting extrusion (RUE) is dominated by a complicated combination of continuous dynamic recrystallization and discontinuous dynamic recrystallization. The RUEed alloys under different starting temperatures exhibited a bimodal microstructure comprising fine DRXed grains with weak texture and coarse deformed grains with strong texture. The DRXed grains could weaken the texture. As the RUE starting temperature decreased, the average grain size increased and the volume fraction of DRXed grains decreased.

Study on the Electrochemical Behavior of Al-6Zn-0.02In-1Mg-0.03Ti Sacrificial Anodes for Long-Term Corrosion Protection in the Ocean

CORROSION ◽  
10.5006/3404 ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 366-372 ◽  
Author(s):  
Mingkun Yang ◽  
Yan Liu ◽  
Zeyao Shi ◽  
Xiaodan Lv ◽  
Bin Liu ◽  
...  
Keyword(s):  
Mass Loss ◽  
Corrosion Product ◽  
Cathodic Protection ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Output Current ◽  
Alloy Anode ◽  
Sacrificial Anodes

After 10 y of service in the ocean, the long-term performance of Al-6Zn-0.02In-1Mg-0.03Ti aluminum alloy sacrificial anodes for steel piles was characterized by mass loss in addition to optical and electron microscopy analysis. The electrochemical behavior was conducted by open-circuit potential with potentiodynamic and potentiostatic polarizations. The results showed that cathodic protection potential was in the range of −0.960 VCSE to −1.103 VCSE. The corrosion type and consumption rate of the alloy anode were related to the output current. In harsh corrosion environments, the alloy anode showed uniform corrosion and lost more mass due to voltage output, therefore more current is needed to fulfill cathodic protection. Otherwise, localized corrosion and less mass loss were observed. The alloy anodes were covered by marine creatures and corrosion product. The corrosion product contained amorphous Al(OH)3 and MgAl2(CO3)(OH)·xH2O which became more crystalline from outside to inside of the alloy anode. A translucent corrosion product was found on the alloy anode surface which contained amorphous Al(OH)3·xH2O with S, along with AlxCly(OH)z·mH2O. The electrochemical performance of the alloy anode was strongly reduced by the coverage of corrosion product. Consequently, the open-circuit potential of the alloy anode increased and the output current decreased. The effect of corrosion product thicknesses on the anodic activation is not remarkable.

Comparative Electrochemical Performance Characteristics of Aluminium-Air Cell Employing Seawater and NaCl Electrolytes

2013 ◽  
Vol 701 ◽  
pp. 314-318 ◽  
Author(s):  
Maziati Akmal ◽  
Raihan Othman ◽  
Mohd Hanafi Ani
Keyword(s):  
Electrochemical Performance ◽  
Discharge Capacity ◽  
Open Circuit Potential ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Conductivity Data ◽  
Water Binding ◽  
Binding Effect ◽  
Electrolyte Conductivity ◽  
Exposed Cell

The electrochemical performance of Al-air cell employing seawater and NaCl electrolyte of various concentrations has been investigated. The open circuit voltage and discharge capacity of the cell correlate well with the electrolyte conductivity data. Using 4 M NaCl electrolyte which possesses the highest conductivity, the Al-air cell registers an open circuit potential (OCV) of 1.1 V and demonstrates discharge capacity of 250 mAh, rated at 1 mA. Upon employing seawater, the OCV reduced to 0.68 V and discharge capacity decreased to 150 mAh. However, utilizing an exposed cell configuration which mitigates the hydroxide gel water binding effect, the Al-air seawater cell performance is greatly enhanced until almost compatible to Al-air cell employing 4 M NaCl.

Enhanced electrochemical performance of Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In fabricated from commercially pure aluminum for use as the anode of alkaline batteries

RSC Advances ◽  
2016 ◽  
Vol 6 (33) ◽  
pp. 28055-28062 ◽  
Author(s):  
Hamed Moghanni-Bavil-Olyaei ◽  
Jalal Arjomandi
Keyword(s):  
Electrochemical Performance ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Pure Aluminum ◽  
Time Measurement ◽  
Open Circuit ◽  
Alkaline Batteries ◽  
Commercially Pure ◽  
Galvanostatic Discharge ◽  
Enhanced Electrochemical Performance

The electrochemical performance of Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In (wt%) from commercially pure aluminum has been determined using open circuit potential–time measurement, galvanostatic discharge, potentiodynamic polarization and electrochemical impedance spectroscopy.

Grain Refinement in Titanium-Erbium Alloys

1974 ◽  
Vol 32 ◽  
pp. 522-523
Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Grain Refinement ◽  
Grain Growth ◽  
Volume Fraction ◽  
Pure Titanium ◽  
Systematic Investigation ◽  
Second Phase ◽  
Titanium Matrix ◽  
Average Size

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.

Adsorption and Oxidation of Thiosulfate on the Platinum Electrode in a Slightly Alkaline Medium

2000 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Tomáš Loučka
Keyword(s):  
Alkaline Medium ◽  
Oxidation Reaction ◽  
Open Circuit Potential ◽  
Platinum Electrode ◽  
Adsorbed Layer ◽  
Open Circuit ◽  
Adsorbed Hydrogen ◽  
Oxidation Number ◽  
Hydrogen Electrode ◽  
Layer Region

The aim of this research was to study the oxidation and reduction of the adsorbed thiosulfate on the platinum electrode in a slightly alkaline medium. The adsorption was performed at the open circuit conditions. The reduction of the adsorbed layer in the hydrogen region is slower in a slightly alkaline medium than in acid. The mechanism of reduction and oxidation of adsorbed molecules is probably the same. The nonstationary currents measured in presence of thiosulfates showed that the change in the oxidation number does not take place during the adsorption in the double layer region. In the hydrogen region, thiosulfate replaces the adsorbed hydrogen while beeing reduced. Nonstationary currents at higher concentrations of thiosulfate indicate the presence of more layers on the electrode. Upon reaching higher concentrations of thiosulfate the oxidation reaction takes place between thiosulfate in solution and adsorbed product of its reduction. The open circuit potential of the platinum electrode measured in a thiosulfate solution was 0.780 and 0.783 V against the hydrogen electrode in the same solution.

scholarly journals Effects of Alloying Elements on the Corrosion Behavior of Sputter–deposited Zr–(12–21)Cr–W Alloys in 0.5 M NaCl Solution

1970 ◽  
Vol 25 ◽  
pp. 75-82
Author(s):  
Basu Ram Aryal ◽  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Test ◽  
Open Circuit Potential ◽  
Chemical Society ◽  
Open Circuit ◽  
Sputter Deposition ◽  
Nacl Solution ◽  
Corrosion Rates ◽  
Sputter Deposited ◽  
Stable Passivity ◽  
Zirconium Metal

The synergistic effect of the simultaneous additions of tungsten and zirconium in thesputter-deposited amorphous or nanocrystalline Zr-(12-21)Cr-W alloys is studied in 0.5 MNaCl solution open to air at 25°C using corrosion tests and open circuit potentialmeasurements. Corrosion rates of the sputter-deposited Zr-(12-21)Cr-W alloys containing10-80 at % tungsten (that is, 0.95-1.85 x 10-2 mm.y-1) are more than one order of magnitudelower than that of the sputter-deposited tungsten and even lower than those of zirconium aswell as chromium in 0.5 M NaCl solution. The addition of 8-73 at % zirconium content inthe sputter-deposited binary W-(12-21)Cr alloys seems to be more effective to improve thecorrosion-resistant properties of the sputter-deposited ternary Zr-Cr-W alloys containing12-21 at % chromium in 0.5 M NaCl solution. The sputter-deposited Zr-(17-21)Cr-W alloyscontaining an adequate amounts of zirconium metal showed the more stable passivity andshowed higher corrosion resistance than those of alloy-constituting elements in 0.5 M NaClsolution open to air at 25°C.Keywords: Zr-(12-21)Cr-W alloys, sputter deposition, corrosion test, open circuit potential,0.5 M NaCl.DOI:  10.3126/jncs.v25i0.3305Journal of Nepal Chemical Society Volume 25, 2010 pp 75-82

scholarly journals Mechanical properties, deformation and fracture mechanisms of bimodal Cu under tensile test

2021 ◽  
Vol 60 (1) ◽  
pp. 15-24
Author(s):  
Silu Liu ◽  
Yonghao Zhao
Keyword(s):  
Yield Strength ◽  
Grain Refinement ◽  
Volume Fraction ◽  
Shear Fracture ◽  
High Strength ◽  
Tensile Specimen ◽  
Deformation Mechanisms ◽  
Fracture Mechanisms ◽  
Fracture Angle ◽  
Area Reduction

Abstract Metals with a bimodal grain size distribution have been found to have both high strength and good ductility. However, the coordinated deformation mechanisms underneath the ultrafine-grains (UFGs) and coarse grains (CGs) still remain undiscovered yet. In present work, a bimodal Cu with 80% volume fraction of recrystallized micro-grains was prepared by the annealing of equal-channel angular pressing (ECAP) processed ultrafine grained Cu at 473 K for 40 min. The bimodal Cu has an optimal strength-ductility combination (yield strength of 220 MPa and ductility of 34%), a larger shear fracture angle of 83∘ and a larger area reduction of 78% compared with the as-ECAPed UFG Cu (yield strength of 410 MPa, ductility of 16%, shear fracture angle of 70∘, area reduction of 69%). Grain refinement of recrystallized micro-grains and detwinning of annealing growth twins were observed in the fractured bimodal Cu tensile specimen. The underlying deformation mechanisms for grain refinement and detwinning were analyzed and discussed.

scholarly journals Miniaturization effect of electroosmotic self-propulsive microswimmer powered by biofuel cell

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Toshiro Yamanaka ◽  
Fumihito Arai
Keyword(s):  
Theoretical Model ◽  
Femtosecond Laser ◽  
Polymer Composites ◽  
Open Circuit Potential ◽  
Vascular System ◽  
Conductive Polymer ◽  
Open Circuit ◽  
Biofuel Cell ◽  
Remarkable Feature ◽  
Conductive Polymer Composites

AbstractFor future medical microrobotics, we have proposed the concept of the electroosmotic self-propulsive microswimmer powered by biofuel cell. According to the derived theoretical model, its self-propulsion velocity is inversely proportional to the length of the microswimmer, while it is proportional to the open circuit potential generated by the biofuel cell which does not depend on its size. Therefore, under conditions where those mechanisms work, it can be expected that the smaller its microswimmer size, the faster its self-propulsion velocity. Because of its remarkable feature, this concept is considered to be suitable as propulsion mechanisms for future medical microrobots to move inside the human body through the vascular system, including capillaries. We have already proved the mechanisms by observing the several 10 μm/s velocity of 100 μm prototypes fabricated by the optical photolithography using several photomasks and alignment steps. However, the standard photolithography was not suitable for further miniaturization of prototypes due to its insufficient resolution. In this research, we adopted femtosecond-laser 3D microlithography for multi-materials composing of the conductive polymer composites and nonconductive polymer composite and succeeded in fabricating 10 μm prototypes. Then we demonstrated more than 100 μm/s velocity of the prototype experimentally and proved its validity of the smaller and faster feature.

scholarly journals Activated Carbon Open Circuit Potential Shifts in Aqueous Solutions

2019 ◽  
Vol 11 (20) ◽  
pp. 19-28 ◽  
Author(s):  
Mikhail M. Goldin ◽  
Gary J. Blanchard ◽  
Alexander G. Volkov ◽  
Mogely S. Khubutiya ◽  
Vladimir A. Kolesnikov ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Aqueous Solutions ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Potential Shifts
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