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

The Effect of Cover Thickness to Corrosion Characteristics of Reinforced Steel Bar Emedded in Mortar Specimen (W/C:0.6) Aged 5 Years in Seawater

2013 ◽  
Vol 785-786 ◽  
pp. 1176-1180 ◽  
Author(s):  
Sung Yul Lee ◽  
Jong Pil Won ◽  
Dong Hyun Park ◽  
Myeong Hoon Lee ◽  
Kyung Man Moon
Keyword(s):  
Corrosion Resistance ◽  
Polarization Resistance ◽  
Corrosion Potential ◽  
Polarization Curves ◽  
Cyclic Voltammograms ◽  
Economic Point ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Reinforced Steel ◽  
Cover Thickness

Reinforced concrete structures have been increasingly widely used through numerous industrial fields. These structures are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain, and the seashore. Thus, corrosion problems of the steel bars embedded in concrete are very important from a safety and economic point of view. In this study, the effects of cover thickness on the corrosion properties of reinforced steel bar embedded in mortar specimen (W/C:0.6) were investigated using electrochemical methods such as corrosion potentials, polarization curves, cyclic voltammograms, galvanostat and potentiostat. Corrosion potentials shifted to the noble direction, and the value of AC impedance also exhibited a higher value with increasing cover thickness, furthermore, polarization resistance also increased with increasing cover thickness. This is probably that the thinner cover thickness, seawater solution is easy to arrive at embedded steel compared to other thicker cover thickness, so, its steel bar may be easily corroded due to chloride ion, which is resulted in shifting corrosion potential to negative direction, decreasing polarization resistance. Consequently, it is considered that the relation between corrosion resistance of reinforced steel and cover thickness is nearly matched with each other. However, its corrosion resistance estimated by measurement of corrosion potential was not well in agreement with value obtained by polarization curves.

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

Evaluation of the corrosion potential in armed concrete as a function of armature covering

2021 ◽  
Author(s):  
Lázaro Rodrigues Penna ◽  
Maria Luísa Freitas dos Santos Honório ◽  
João Victor Laurindo Siqueira ◽  
Diogo Pereira dos Santos Kropf
Keyword(s):  
Corrosion Potential ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Potential Range ◽  
Hardened Concrete ◽  
Corrosion Monitoring ◽  
Potential Measurement ◽  
External Agents ◽  
Cover Thickness ◽  
Corrosion Of Steel

In concrete structures, it is not uncommon to observe the presence of pathological problems that can often be associated with high temperature range, inadequate execution of works, inefficient projects, materials without quality control, unprepared labor, harmful external agents, among others. Among the pathological manifestations of hardened concrete is the corrosion of steel reinforcement, directly influencing the durability and strength of concrete structures. The object of this research is to analyze the influence of concrete cover thickness and chloride contamination on the potential readings of reinforcement corrosion. Since the cover thickness has a direct influence on the potential readings in chloride contaminated concrete. The corrosion potential measurement method will be used as an electrochemical tool to assist in the corrosion monitoring of reinforced concrete structures. As a standard for the evaluation results, the corrosion potential range recommended by ASTM C 876: 2015 and its relationship with the possibility of corrosion is normally used. With the results obtained during the application of this method, it is possible to identify regions where the reinforcement presents corrosion and how the process of steel depassivation is distributed in the region under study. Therefore, it is expected to verify the influence that the concrete cover has on chloride contamination and also influence the values of the corrosion potential.

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.

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