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.

Study of Effect of Ce-Rich Mixed Rare Earth on Corrosivity of New 5XXX Series Aluminium Alloys

2011 ◽  
Vol 314-316 ◽  
pp. 1449-1455 ◽  
Author(s):  
Hua Shen ◽  
He Liang ◽  
Wei Dong Yang ◽  
Bing Xiang Liu ◽  
Tian Shu Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Aluminium Alloys ◽  
Anodic Polarization ◽  
Corrosion Current ◽  
Polarization Curves ◽  
Nyquist Diagram ◽  
Rare Earth Content

In this paper, AL-Mg-Mn-RE series alloys are becamed object of study.They are prouced with pure alumimum, pure Mg,electrolytic Mn and mix rich Ce rare earth. The effect of rare earth content on the resistance of the Al-Mg-Mn-RE series alloys are investigated by using Anodic polarization curves, electrochemical impendance spectroscopy. The results showed that their corrosivity is influenced by RE content in aluminum alloys.NO.3.3 impedance of Al-Mg-Mn-RE alloys is larger in the Nyquist diagram and its corrosion current of alloy decreases obviously. Then corrosivity of alloy is the best and the RE content is 0.3%,When the RE content is higher or lower than it that corrosivity isn’t improved but descended.

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.

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 Galvanic Corrosion between Depleted Uranium and 40Cr Steel

2012 ◽  
Vol 531-532 ◽  
pp. 220-225
Author(s):  
Zhen Pu ◽  
Qing Fu Wang ◽  
Mao Bin Shuai ◽  
Ding Mu Lang
Keyword(s):  
Current Density ◽  
Linear Polarization ◽  
Galvanic Corrosion ◽  
Corrosion Current ◽  
Open Circuit ◽  
Depleted Uranium ◽  
Accelerated Corrosion ◽  
Linear Polarization Resistance ◽  
Corrosion Behaviors ◽  
40Cr Steel

Individual corrosion and galvanic corrosion behaviors of depleted uranium (DU) and 40Cr steel were investigated by electrochemical analyzing technologies in 3.5w.t%NaCl solution, including open circuit potential(OCP) test, linear polarization(LP) test, potentiodynamic polarizaition(PD) test, galvanic corrosion potential and corrosion current density test. The results reveal that the OCP of DU and 40Cr steel are around -790mV and -660mV, respectively. 40Cr has a higher linear polarization resistance than DU in galvanic corrosion. The dynamic processes of galvanic corrosion goes through an conversion in the whole test period. DU acts as anode with an accelerated corrosion rate, while the 40Cr steel behaves as cathode during the process of galvanic corrosion for DU/40Cr couple. The galvanic potential and current density of the DU/40Cr couple are -780mV and 17.5μA/cm-2, respectively.

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

Coating Thickness of Reinforced Concrete Affecting to Cathodic Polarization and Cyclic Voltammogram of Reinforced Steel

2016 ◽  
Vol 723 ◽  
pp. 741-747
Author(s):  
Kyung Man Moon ◽  
Sung Yul Lee ◽  
Jae Hyun Jeong ◽  
Myeong Hoon Lee
Keyword(s):  
Current Density ◽  
Coating Thickness ◽  
Corrosion Current Density ◽  
Cathodic Polarization ◽  
Sea Water ◽  
Corrosion Current ◽  
Corrosion Products ◽  
Cyclic Voltammogram ◽  
Steel Bar ◽  
Reinforced Steel

The reinforced concretes are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Therefore, the reinforced steel bar embedded in the concrete is increasingly corroded in various environments mentioned above, and this corrosion problem is thought to be very important in terms of the safety and economic points of view. In this study, a multiple mortar test specimen(W/C:0.5) with variation of coating thickness was prepared and immerged in flowing seawater for five years. And, the effects of coating thickness affecting to cathodic polarization and cyclic voltammogram were investigated using electrochemical methods. The thinner coating thickness, both invasion and diffusion of dissolved oxygen, water and chloride ion on the surface of reinforced steel bar is more easily compared to the thicker coating thickness. Thus, at the beginning of immersion, the rate of corrosion in the case of the thinner coating thickness is higher than that of the thicker coating thickness. However, it is considered that corrosion products deposited on the surface due to higher corrosion rate played the role as a resistance polarization, and increased the diffusion layer, as a result, decreased the corrosion current density compared to the thicker coating thickness. Consequently, the relationship between corrosion current density and the coating thickness were not well in good agreement with each other due to the corrosion products after being immersed for 5 years. Therefore, in order to more optimum evaluate for corrosion possibility of the reinforced steel embedded in the concrete, not only corrosion potential but also other parameters such as coating thickness, W/C ratio, and other corrosion environment should be investigated in the case of immersed in seawater for long years.

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

Anodic Polarization Characteristics Of Gold and Silver In Chloride and Sulfate Media

CORROSION ◽  
1963 ◽  
Vol 19 (4) ◽  
pp. 115t-119t ◽  
Author(s):  
F. P. A. ROBINSON ◽  
F. A. FROST
Keyword(s):  
Anodic Polarization ◽  
Current System ◽  
Anodic Polarization Curve ◽  
Chloride Ions ◽  
Passive State ◽  
Anode Reaction ◽  
Polarization Characteristics ◽  
Impressed Current ◽  
The Stability ◽  
A Current

Abstract The anodic polarization characteristics of gold and silver in chloride and sulfate media have been studied, employing potentiostatic techniques. It was found that gold produces an active-passive S-shaped curve, the form of which is not seriously affected by the presence of oxygen in the electrolyte. The stability of the passive state was greater in the sulfate than in the chloride media. Silver does not give a typical anodic polarization curve in NaCl solution, because formation of an AgCl film is the primary anode reaction. This film thickens and exfoliates at a current density of 2 a/sq ft. For this reason, silver could not be used as an inexpendable anode in an impressed current system containing chloride ions.

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