Influence of Cu on the Passivation Behavior of Fe-20Cr-xCu (x = 0, 2, 4 wt%) Alloys in Sulfuric Acid Solution

CORROSION ◽  
10.5006/0673 ◽  
2013 ◽  
Vol 69 (6) ◽  
pp. 560-567 ◽  
Author(s):  
KkochNim Oh ◽  
Ihsan-ul-Haq Toor ◽  
SooHoon Ahn ◽  
HyukSang Kwon
Keyword(s):  
Sulfuric Acid ◽  
Oxidation Reaction ◽  
Saturated Calomel Electrode ◽  
H2so4 Solution ◽  
Passive Current Density ◽  
Applied Potential ◽  
Passive Region ◽  
Cu Content ◽  
Passive Current ◽  
Preferential Dissolution

Effects of Cu on the polarization behavior of Fe-20Cr-xCu (x = 0, 2, 4 wt%) were examined in deaerated 0.1 M sulfuric acid (H2SO4) solution. In the active region, corrosion resistance of the alloys is improved with Cu content as a result of the enrichment of Cu on the surface of the alloys that occurs by the preferential dissolution of Fe. In the passive region, the effects of Cu on the passivation behavior of the alloys was dependent on the applied potential. At potentials active to −100 mV vs. saturated calomel electrode (SCE), the passivity of the alloys is improved with Cu content, which is confirmed by the increase in passivation rate with a decrease in oxidation tendency. In contrast, above −100 mVSCE, where the oxidation reaction of Cu+ to Cu2+ occurs, the passivity of the alloys was degraded significantly with Cu content, as confirmed by the increase in passive current density as well as the significant decrease in passivation rate. The deleterious effects of Cu on the passivation behavior of Fe-20Cr-xCu (x = 0, 2, 4 wt%) decreased at potentials noble to 500 mVSCE, primarily as a result of the significant decrease in Cu content in passive film and hence of the decrease in the oxidation reaction of Cu+ to Cu2+.

CORROSION AND WEAR PROPERTIES OF ELECTRODEPOSITED TERTIARY NANOCOMPOSITE Zn–Ni (ALUMINA–YITTRIA–GERAPHENE) COATING

2016 ◽  
Vol 24 (05) ◽  
pp. 1750066 ◽  
Author(s):  
HAMED RAHMANI ◽  
MAHMOOD ALIOFKHAZRAEI ◽  
ABDOSSALAM KARIMZADEH
Keyword(s):  
Duty Cycle ◽  
Zinc Sulphate ◽  
Pulse Current ◽  
Corrosion And Wear ◽  
Pulsed Current ◽  
Passive Current Density ◽  
Wear Properties ◽  
Nickel Zinc ◽  
Pulsed Electrodeposition ◽  
Passive Current

Nanocomposite Ni–Zn coatings containing 80 wt.% Al2O3, 5 wt.% Y2O3 and 15 wt.% graphene were fabricated by pulsed electrodeposition method in nickel–zinc sulphate-based electrolyte and effects of pulse current parameters on nickel and other element contents, microstructure, resistance to corrosion and tribological properties of the coatings were investigated. The pulsed current with duty cycle from 10% to 50% was applied to different samples and frequency changed gradually from 500 to 4000[Formula: see text]Hz in five steps during coating process. Increasing the duty cycle led to decrease of absorbed nanoparticles in the surface of the coatings from 4.4 vol% to 3.58 vol% The sample coated with 10% duty cycle had utmost alumina content in the coating surface, 3.5 vol% in first layer up to 4.4 vol% in fifth layer. The sample coated with 30% duty cycle had higher corrosion resistance with passive current density of 2.5[Formula: see text]mA/cm2. Furthermore, the results showed that by increasing the duty cycle, wear rate had been increased up to 1.3[Formula: see text][Formula: see text][Formula: see text]10[Formula: see text][Formula: see text]mm2/N[Formula: see text]m.

Effect of Halide Additions on Anodic Behavior of Nickel in Sulfuric Acid Solutions

CORROSION ◽  
1967 ◽  
Vol 23 (4) ◽  
pp. 109-114 ◽  
Author(s):  
JOHN POSTLETHWAITE ◽  
LEONARD B. FREESE
Keyword(s):  
Sulfuric Acid ◽  
Corrosion Potential ◽  
Negative Slope ◽  
Potential Range ◽  
Anodic Behavior ◽  
Passive Region ◽  
Hydrogen Electrode ◽  
Passive Transition ◽  
Passivation Potential ◽  
Sulfuric Acid Solutions

Abstract A potentiokinetic study, dE/dt = 950 mV/hr, has been made of the effects of sodium chloride, bromide and iodide additions, in the range 0.001 to 0.1 M, on the anodic behavior of pure nickel in deaerated N/10 sulfuric acid. Each experiment comprised a forward and reverse sweep in the potential range (relative to the standard hydrogen electrode) −0.5 to +1.2 V. Halide additions affected the anodic behavior of the nickel in both active and passive regions. All halides studied lowered the corrosion potential, raised the primary passivation potential and increased the critical passivation current density. Additions of 0.01 M and greater resulted in elimination of the normal passive region. Reactivation was much greater on reverse sweeps with chloride additions than in either plain acid or with other halides. Negative slope marking the active-passive transition on forward sweep sometimes was eliminated but was evident always on the reverse sweep showing that even when attacks in active and passive regions merge there is a change of electrode process at the normal active passive transition.

An Integrated Sonication Technique for Electrodeposition of Platinum and Ruthenium on Carbon Nanotubes for Methanol Oxidation

2012 ◽  
Vol 9 (4) ◽  
Author(s):  
Tsung-Kuang Yeh ◽  
Yu-Ming Chang ◽  
Chuen-Horng Tsai ◽  
Ming-Chi Tsai ◽  
Mei-Ya Wang
Keyword(s):  
Carbon Nanotubes ◽  
Sulfuric Acid ◽  
Methanol Oxidation ◽  
Cyclic Voltammogram ◽  
Electrochemical Characteristics ◽  
H2so4 Solution ◽  
Peak Current Density ◽  
Surface Distribution ◽  
Ru Nanoparticles ◽  
Sonication Technique

An electrodeposition technique that could significantly improve the deposition of platinum-ruthenium (Pt-Ru) nanoparticles onto carbon nanotubes (CNTs) directly grown on carbon cloths was adopted in this study. Integrated sonication (IS) was activated during the electrodeposition process conducted in a sulfuric acid (H2SO4) solution containing Pt and Ru precursor chemicals of hexachloroplatinic acid and ruthenium trichloride, respectively, and ethylene glycol (EG) as a dispersing agent. In comparison with our earlier work, this new technique would further reduce the size of Pt-Ru particles from 4-6 nm to 2-3 nm and lead to a more even and higher surface distribution of these nanoparticles on the CNTs. In addition, the loadings of Pt and Ru on the CNTs were both markedly increased. Electrochemical characteristics of methanol oxidation on specimens bearing these catalysts (Pt-Ru/CNTs) were investigated via cyclic voltammetry analysis in mixed 1 M methanol and 0.5 M sulfuric acid solutions. It was found that the peak current density of methanol oxidation obtained from the cyclic voltammogram on the new Pt-Ru/CNTs specimen was nearly three times of that on the specimen prepared with EG in the absence of IS. The outcome signified better catalyst morphology and distribution and a significantly improved methanol oxidation efficiency of the new specimen prepared in the mixed EG and H2SO4 solution by electrodeposition in the presence of IS.

Chemiluminescence behavior based on oxidation reaction of rhodamine B with cerium(IV) in sulfuric acid medium

2003 ◽  
Vol 489 (2) ◽  
pp. 173-181 ◽  
Author(s):  
Yongjun Ma ◽  
Xiaoyong Jin ◽  
Min Zhou ◽  
Ziyu Zhang ◽  
Xiulan Teng ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Medium ◽  
Rhodamine B ◽  
Oxidation Reaction ◽  
Sulfuric Acid Medium ◽  
Behavior Based

Methodologies for Predicting the Performance of Ni-Cr-Mo Alloys Proposed for High Level Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
D. S. Dunn ◽  
G. A. Cragnolino ◽  
N. Sridhar
Keyword(s):  
Nuclear Waste ◽  
Current Density ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Aqueous Corrosion ◽  
Wide Range ◽  
Anionic Species ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Passive Current

AbstractFor the geologic disposal of the high level nuclear waste (HLW), aqueous corrosion is considered to be the most important factor in the long-term performance of containers, which are the main components of the engineered barrier subsystem. Container life, in turn, is important to the overall performance of the repository system. The proposed container designs and materials have evolved to include multiple barriers and highly corrosion resistant Ni-Cr-Mo alloys, such as Alloys 625 and C-22. Calculations of container life require knowledge of the initiation time and growth rate of localized corrosion. In the absence of localized corrosion, the rate of general or uniform dissolution, given by the passive current density of these materials, is needed. The onset of localized corrosion may be predicted by using the repassivation and corrosion potentials of the candidate container materials in the range of expected repository environments. In initial corrosion tests, chloride was identified as the most detrimental anionic species to the performance of Ni-Cr-Mo alloys. Repassivation potential measurements for Alloys 825, 625, and C-22, conducted over a wide range of chloride concentrations and temperatures, are reported. In addition, steady state passive current density, which will determine the container lifetime in the absence of localized corrosion, was measured for Alloy C-22 under various environmental conditions.

Effect of pyrite on the electrochemical behavior of chalcopyrite at different potentials in pH 1.8 H2SO4

2019 ◽  
Vol 43 (11-12) ◽  
pp. 493-502
Author(s):  
Qingyou Liu ◽  
Shuai Wang ◽  
Miao Chen ◽  
Yi Yang
Keyword(s):  
Electrochemical Impedance ◽  
Saturated Calomel Electrode ◽  
Surface Characteristics ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Electrochemical Dissolution ◽  
Passive Region ◽  
Transfer Resistance ◽  
Electrochemical Behaviors ◽  
Passive Resistance

Chalcopyrite is the most abundant, but also one of the most refractory, copper sources. One way to enhance chalcopyrite’s electrochemical dissolution is by mixing it with pyrite. To understand how and to what extent pyrite affects chalcopyrite’s electrochemical dissolution at different potentials, the electrochemical behaviors of chalcopyrite, pyrite, and chalcopyrite–pyrite couples in pH 1.8 H2SO4 were studied by potentiodynamic and electrochemical impedance spectroscopy. Potentiodynamic curves showed their different electrochemical reaction states and electrode surface characteristics. From open-circuit potential to 470 mV (vs saturated calomel electrode), chalcopyrite–pyrite was passivated with Cu1− xFe1− yS2 [Formula: see text]; from 470 to 580 mV, trans-passive dissolution occurred, and in the passive region, Cu1− xFe1− yS2 transformed into Cu1− x− zS2; from 580 to 700 mV was an active region; and a pseudo-passive region was formed with CuS when the potential was above 700 mV. The smaller charge transfer resistance and passive resistance, as well as the smaller inductive relaxation, revealed how and to what extent the coupled pyrite accelerated the electrochemical dissolution of chalcopyrite.

Effect of Sulfuric Acid Concentration on Chalcopyrite Concentrate Chemical Leaching

2009 ◽  
Vol 71-73 ◽  
pp. 353-356
Author(s):  
Seong Jin Joe ◽  
Tadashi Chida ◽  
Masatoshi Sakoda ◽  
Hidekatsu Nakamura ◽  
Muneyuki Tamura ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Concentration ◽  
Sulfuric Acid Concentration ◽  
Copper Extraction ◽  
H2so4 Solution ◽  
Chemical Leaching ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Chalcopyrite Concentrate ◽  
Leaching Reaction

This study reports the effect of sulfuric acid concentration on chalcopyrite chemical leaching in very simple H2SO4 solution systems ranging from 23g/L to 30g/L, with 2.5% chalcopyrite concentrate at 30°C. Copper extraction from chalcopyrite increases with an increase in sulfuric acid concentration, e.g. 86%, 90% and 92% after 96 days at 23g/L, 25/L and 27g/L H2SO4 solution respectively. Sulfur element formed on the surface of chalcopyrite was very porous as the result of an electron probe microanalyzer (EPMA). Copper extraction, however, leveled out at 35% after 20 days when the sulfuric acid concentration was higher than 28g/L on 25g/L of chalcopyrite concentrate. Sulfur element was detected by X-ray analysis as only a leaching reaction product. The passivation may be caused by thick elemental surface formed on the surface of chalcopyrite.

An Electrostatically Self-Assembled Thin Film Made of Zn-Substituted Tungstoborate and Rhodamine B with Photoelectrochemical Properties

2016 ◽  
Vol 16 (4) ◽  
pp. 3674-3678 ◽  
Author(s):  
Xu Mao ◽  
Jia-Ning Zhang ◽  
Li-Hua Gao ◽  
Yu Su ◽  
Peng-Xia Chen ◽  
...  
Keyword(s):  
Thin Film ◽  
Rhodamine B ◽  
Indium Tin Oxide ◽  
Saturated Calomel Electrode ◽  
Photocurrent Density ◽  
Layer By Layer ◽  
Applied Potential ◽  
Ito Glass ◽  
Keggin Polyoxometalate ◽  
Self Assembled

An electrostatically self-assembled multilayer thin film consisting of alternating layers of Keggin polyoxometalate of Zn-substituted tungstoborate (BW11Zn) and Rhodamine B (RhB) has successfully been prepared on a quartz and indium-tin oxide (ITO) glass substrate. The ultraviolet-visible (UV-vis) absorption spectra demonstrated that the electrostatically self-assembled film of (BW11Zn/RhB)n was uniformly deposited layer by layer, and the RhB molecules in the film formed the J-aggregation. The photoelectrochemical investigations showed that the films generated stable cathodic photocurrents that originated from RhB, and the maximal cathodic photocurrent density generated by an eight-layer film was 4.9 μA/cm2 while the film was irradiated with 100 mW/cm2 polychromatic light of 730 nm > λ > 325 nm at an applied potential of 0 V versus a saturated calomel electrode.

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