scholarly journals Electrochemical characteristics in the range of general dissolution on anodic polarization curve of aluminum

2003 ◽  
Vol 53 (8) ◽  
pp. 331-336 ◽  
Author(s):  
Osami SERI ◽  
Keiji NANAE
Keyword(s):  
Polarization Curve ◽  
Anodic Polarization ◽  
Anodic Polarization Curve ◽  
Electrochemical Characteristics

Effect of Nitrite Ions on Polarization Behavior of Steel Immersed in Simulated Concrete Pore Environments

2013 ◽  
Vol 368-370 ◽  
pp. 919-924
Author(s):  
Zhong Lu Cao ◽  
Makoto Hibino ◽  
Hiroki Goda
Keyword(s):  
Polarization Curve ◽  
Current Density ◽  
Linear Polarization ◽  
Anodic Polarization ◽  
Cathodic Polarization ◽  
Corrosion Current ◽  
Anodic Polarization Curve ◽  
Polarization Curves ◽  
Passive State ◽  
Nitrite Concentration

The influence of nitrite concentration on the linear polarization curves of steel, Tafel slope and Stern-Geary constant B have been investigated in three different pH environments simulating the highly alkaline environment, carbonated environment and neutral environment that really existed on the surface of steel in concrete. The results indicate that when the steel is in passive state, the presence of nitrite has little influence on anodic/cathodic polarization curves and Stern-Geary constant B; but when the steel is corroded, the presence of nitrite not only reduces the current density of anodic polarization curve but also decreases the value of Stern-Geary constant B. If this influence is not considered in practical corrosion measurement, the corrosion current will be overestimated.

Electrochemical Behaviour of Cobalt in NaOH Solutions

1994 ◽  
Vol 59 (11) ◽  
pp. 2383-2389 ◽  
Author(s):  
Sayed S. Abd El Rehim ◽  
Ahmed A. El Basosi ◽  
Salah M. El Zein ◽  
Magda M. Osman
Keyword(s):  
Cyclic Voltammetry ◽  
Passive Film ◽  
Polarization Curve ◽  
Anodic Polarization ◽  
Electrochemical Behaviour ◽  
Anodic Polarization Curve ◽  
Potential Region ◽  
Voltammetric Techniques ◽  
Scan Rate ◽  
Reverse Scan

The electrochemical behaviour of cobalt in 0.001 - 1 M NaOH was investigated by voltammetric techniques coupled with ESCA examination. The anodic polarization curve exhibits a well defined peak which corresponds to the formation of Co(OH)2 or CoO. Further peaks in the transpassive potential region correspond to the electrooxidation of Co(II) species to Co3O4 and CoOOH, respectively. The heights of the anodic peaks increase with the increase of NaOH concentration, temperature and scan rate. In cyclic voltammetry, the reverse scan consistently shows three cathodic peaks which are ascribed to the reduction of CoOOH, Co3O4 and CoO oxides, respectively. ESCA examination confirmed the presence of these oxides in the passive film.

scholarly journals Effects of Bicarbonate Ion and Silica on Anodic Polarization Curve of Carbon Steel

2004 ◽  
Vol 53 (9) ◽  
pp. 434-439 ◽  
Author(s):  
Masayuki Itagaki ◽  
Yoshinobu Yamada ◽  
Kunihiro Watanabe ◽  
Takahiro Nukaga ◽  
Fumio Umemura
Keyword(s):  
Carbon Steel ◽  
Polarization Curve ◽  
Anodic Polarization ◽  
Anodic Polarization Curve

Effects of Foreign Metals on Corrosion of Titanium In Boiling 2M Hydrochloric Acid

CORROSION ◽  
1959 ◽  
Vol 15 (11) ◽  
pp. 26-30 ◽  
Author(s):  
ROGER BUCK ◽  
BILLY W. SLOOPE ◽  
HENRY LEIDHEISER
Keyword(s):  
Hydrochloric Acid ◽  
Corrosion Rate ◽  
Polarization Curve ◽  
Nickel Alloys ◽  
Anodic Polarization ◽  
Saturated Calomel Electrode ◽  
Anodic Polarization Curve ◽  
Cobalt Nickel ◽  
Metallic Cations ◽  
Made In

Abstract The rate of corrosion of titanium was determined in boiling 2M HC1 when contacted to aluminum, cadmium, tin, zirconium, lead, bismuth, mercury, silver, copper, antimony, vanadium, 70:30, 50:50 and 30:70 copper-nickel alloys, iron, palladium, cobalt, nickel, gold, rhodium, platinum and iridium. Less extensive corrosion measurements of the same type were also made in 0.6 and 2M H2SO4. The potentials of the couple and of the two members of the couple were determined in boiling 2M HC1 for 20 of the systems studied. A plot of the corrosion rate vs the couple potential yielded a polarization curve which was similar to the anodic polarization curve for titanium with an impressed voltage. The curve exhibited a maximum in corrosion rate at a couple potential of —0.49-volt vs the saturated calomel electrode. The potential of titanium in boiling 2 M HC1 was also determined as a function of concentration of the following metallic cations in the acid: copper, silver, antimony, nickel, gold, palladium, rhodium, platinum and iridium. The influence of the cations on the corrosion rate was explained in relation to the polarization curve. 6.3.15

scholarly journals Electrode processes during electrodeposition, electropolishing and oxidation of niobium

2021 ◽  
Vol 12 (2-2021) ◽  
pp. 192-196
Author(s):  
M. A. Okunev ◽  
◽  
S. A. Kuznetsov ◽  
Keyword(s):  
Cyclic Voltammetry ◽  
Formation Mechanism ◽  
Polarization Curve ◽  
Anodic Polarization ◽  
Film Formation ◽  
Anodic Polarization Curve ◽  
Niobium Pentoxide ◽  
Potential Range ◽  
Electrode Processes ◽  
Film Formation Mechanism

The electrode processes occurring during the electrodeposition, electropolishing and oxidation of niobium are considered. The discharge of Nb(IV) complexes during Nb electrodeposition was studied by cyclic voltammetry. The anodic polarization curve on niobium in a mixture of acids H2SO4:HF (9:1) was obtained by chronopotentiometry method, the potential range at which the highest quality and speed of electropolishing is achieved was found. The film formation mechanism of niobium pentoxide Nb2O5 on niobium was studied by cyclic voltammetry.

Sulfates in the Passive Iron Layer

CORROSION ◽  
1964 ◽  
Vol 20 (9) ◽  
pp. 275t-281t ◽  
Author(s):  
O. L. RIGGS
Keyword(s):  
Steady State ◽  
Polarization Curve ◽  
Anodic Polarization ◽  
Saturated Calomel Electrode ◽  
Anodic Polarization Curve ◽  
Iron Layer ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Polarization Data ◽  
X Ray

Abstract Anodic polarization data were obtained on iron in 20 N H2SO4 at 25 C (77 F). Along the polarization curve, the potential was held constant at 20 mv increments and the current was recorded at the end of 60 minutes. Minimum currents, the average of four experiments, were noted at 260, 520, 810, 1060, 1320 and 1600 mv noble potential with reference to the saturated calomel electrode (S.C.E.). The various chemical compositions were identified with reproducible X-ray diffraction data. A technique involving an ethyl alcohol rinse permitted the X-ray study of the passive surface. The passive iron layer was identified as FeSO4.H2O, Fe2(SO4)3 H2O,FeSO4.4H2O and as FeSO4.7H2O at 260, 520, 810 and 1320 mv noble to S.C.E., respectively. The structures were reported to be responsible for the steady-state minimum currents. The X-ray diffraction values of the specimens held at 1060 and 1600 mv (S.C.E.) were not identified. The anodic polarization curve was discussed in terms of specific electrochemical events.

Passing Aged Years to Polarization Characteristics of the Steel Bar Embedded in Mortar Specimen (W/C:0.4)

2013 ◽  
Vol 821-822 ◽  
pp. 1227-1231
Author(s):  
Sung Yul Lee ◽  
Jong Pil Won ◽  
Dong Hyun Park ◽  
Jae Hyun Jeong ◽  
Kyung Man Moon
Keyword(s):  
Polarization Curve ◽  
Anodic Polarization ◽  
Corrosion Potential ◽  
Anodic Polarization Curve ◽  
Industrial Society ◽  
Positive Direction ◽  
Potential Measurement ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Cover Thickness

The structures of reinforced concrete has been extensively increased with rapid development of industrial society. Furthermore, these reinforced concretes are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Thus, the corrosion problem of a steel bar embedded in the concrete is very important in terms of the safety and economic points of view. In this study, a multiple mortar test specimen (W/C:0.4) that had six types of cover thickness was prepared and immerged in flowing seawater for five years. And the effects of cover thickness and immersion years on the corrosion properties of the steel bars were investigated using electrochemical methods such as measuring corrosion potential, anodic polarization curve, and impedance. At the beginning of immersion (0 year), corrosion potentials exhibited increasingly nobler value with increasing the cover thickness. However, after being immersed for 5 years, the corrosion potentials conversely shifted in the positive direction with decreasing the cover thickness. As a result, the relationships between corrosion potential and cover thickness were not in good agreement with each other after 5 years. In addition, after 5 years, the thinner cover thickness, the higher value of impedance at 0.01Hz. It is considered that corrosive products deposited on the surface of the steel bar embedded in mortar specimen in the case of thinner cover thickness played the role as a resistance polarization which resulted in decreasing the corrosion current density. Consequently, it seemed to be somewhat problem that evaluation on the corrosion property in reinforced steel would be estimated by only the corrosion potential measurement. Therefore, it is suggested that we should take into account various parameters such as cover thickness, corrosion potential, and immersed years etc. for its accurate assessment. Keywords : Cover thickness, Corrosion potential, Anodic polarization curve, Impedance, Resistance polarization

Effects of Current Density on the Formation of Anodic Oxide Films on AZ91

2006 ◽  
Vol 510-511 ◽  
pp. 166-169
Author(s):  
Seong Jong Kim ◽  
Jeong Il Kim
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Anodic Polarization ◽  
Oxide Films ◽  
Anodic Oxide ◽  
Anodic Polarization Curve ◽  
Al Alloy ◽  
Anodic Oxide Films ◽  
Active Metal ◽  
Naoh Solution

Magnesium must be surface treated to prevent corrosion, since it is a very active metal electrochemically. On anodizing, a compact film several tens of micrometers thick forms on magnesium, which imparts good corrosion resistance. The Mg-Al alloy (AZ91) was anodized in 1 M NaOH solution. The surface morphology of the anodized films was observed using scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), and electrochemical methods. The effects of current density on the formation of anodic oxide films for a Mg-Al alloy in 1 M NaOH were investigated. In the anodic polarization curve, the reference corrosion potentials were far greater at 4-9 mA/cm2 than at 1 mA/cm2. The film that formed at 1 mA/cm2 was thin, suggesting that parts of the film had been dissolved or destroyed during the anodic polarization test. Corrosion resistance differed owing to concentric differences in current flow. Thick anodic oxide films were formed at higher applied currents.

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