scholarly journals Electrolyte Composition for Distinguishing Corrosion Mechanisms in Steel Alloy Screening

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Ingmar Bösing ◽  
Jorg Thöming ◽  
Michael Baune
Keyword(s):  
Pitting Corrosion ◽  
Material Characterization ◽  
Corrosion Potential ◽  
Electrolyte Composition ◽  
Cyclic Voltammograms ◽  
Metal Structures ◽  
Cause Of Failure ◽  
Similar Materials ◽  
Corrosion Mechanisms ◽  
Passive Area

The formation and breakdown of passive layers due to pitting corrosion are a major cause of failure of metal structures. The investigation of passivation and pitting corrosion requires two different electrochemical measurements and is therefore a time consuming process. To reduce time in material characterization and to study the interactions of both mechanisms, here, a combined experiment addressing both phenomena is introduced. In the presented electrolyte the different corrosion mechanisms are distinguished and investigated by cyclic voltammograms and polarization scans. The measurements show a passive area, metastable pit growth, and pitting corrosion as well as repassivation. The pitting corrosion is separated from additional dissolution processes and the standard deviation of the corrosion potential is smaller than in other electrolytes. Both passivation and pitting corrosion can be observed in one measurement without additional corrosion attacks. The deviation between different measurements of the same steel is small; this is helpful for the screening of similar materials.

Experimental Study of Propagation Stage of Pitting Corrosion of 20Cr13 Steel

2008 ◽  
Vol 38 ◽  
pp. 238-247
Author(s):  
A.D. Davydov ◽  
V.S. Shaldaev
Keyword(s):  
Pitting Corrosion ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Ph Value ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Pitting Potential ◽  
Free Corrosion Potential ◽  
External Power Source ◽  
Corrosion Of Steel

The initiation and development of pitting corrosion of steel 20Cr13 in the NaCl solutions with various concentrations, temperatures, and pH values are studied under the potentiostatic conditions and at the free-corrosion potential. The pitting and repassivation potentials are determined using the method of cycling voltammetry. In spite of the fact that thus determined pitting potential is more positive than the corrosion potential (the open-circuit potential Eo.c.), the long-term experiments, which were performed at the free-corrosion potential, showed that pitting corrosion takes place without imposing a potential using an external power source. It is concluded that the probability of pitting corrosion of steel should be determined by comparing the corrosion potential (the open-circuit potential) with the repassivation potential Erp. Steel 20Cr13 is prone to the pitting corrosion, because Erp is more negative than Eo.c.. In the potentiostatic experiments, the variation of the depth and diameter of pits and their number with the time and the effect of temperature and electrode rotation on the pit propagation are studied. The results, which were obtained at the free-corrosion potential, are much less reproducible. In this case, in contrast to the potentiostatic conditions, the pit depth increased only slightly and the pit width increased to a larger extent. The effect of concentration, pH value, and temperature of NaCl solutions on the pit propagation is considered. It is concluded that the data on the development of pitting corrosion under the potentiostatic conditions can be hardly extended to the conditions of free corrosion potential.

THE INHIBITION EFFECT OF ZINC AND SILICATE IONS ON PITTING CORROSION INDUCED BY CERIUM(III) IONS OF CARBON STEEL IN SODIUM CHLORIDE SOLUTION

2020 ◽  
pp. 2050038
Author(s):  
QIONGWEI LI
Keyword(s):  
Sodium Chloride ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
In Situ Observation ◽  
Inhibition Effect ◽  
Synergistic Inhibition

Pitting corrosion of carbon steel in sodium chloride solution induced by Ce[Formula: see text] and the synergistic inhibition effects of Ce[Formula: see text] and Zn[Formula: see text]/SiO[Formula: see text] were investigated using in-situ observation and electrochemical methods. The results showed that the presence of Ce[Formula: see text] could result in severe pitting corrosion and a positive shift in the corrosion potential. It was found that individual Ce[Formula: see text], Zn[Formula: see text], or SiO[Formula: see text] had low inhibition efficiencies, whereas the combination of Ce[Formula: see text] and Zn[Formula: see text] or SiO[Formula: see text] proved to be highly effective in inhibiting the development of pits in two different ways and in enhancing the corrosion resistance. The pitting corrosion and inhibition mechanisms were discussed based on the results.

scholarly journals Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Injoon Son ◽  
Hiroaki Nakano ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Pure Aluminum ◽  
Electrochemical Techniques ◽  
Oxide Films ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance ◽  
Al Oxide

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3of Na2SO4and 8.46 mol·dm−3of NaCl (300 ppm Cl−) and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films.

scholarly journals The Confocal Scanning Laser Microscopic Study of the Pitting Corrosion on Sputter-Deposited W-Ti Alloys in 1 M NaOH Solution

1970 ◽  
Vol 26 (1) ◽  
pp. 17-26
Author(s):  
Jagadeesh Bhattarai
Keyword(s):  
Passive Film ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Open Circuit ◽  
Scanning Laser ◽  
Ti Alloys ◽  
Naoh Solution ◽  
Confocal Scanning ◽  
Confocal Scanning Laser ◽  
Sputter Deposited

The pitting corrosion of the passive films formed on the surface of sputter-deposited W-30Ti and W-53Ti alloys after immersion for 24 hours in alkaline 1 M NaOH soution at 25°C was studied by using the surface sensitive technique of the confocal scanning laser microscopic (CSLM) technique including corrosion tests and electrochemical measurements. The higher corrosion rate of the W-30Ti alloy (i.e., about 3x 10-2 mm/y) than those of the W-53Ti and W-90Ti alloys (i.e., about 4-5 x 10-3 mm/y) was mostly due to the deep type of pitting corrosion observed on the surface of the passive film formed on the W-30Ti alloy in 1 M NaOH solution. The shallow type of pits was developed on the surface of the passive film formed on the W-53Ti alloy, whereas no pitting corrosion on the titanium-rich W-90Ti alloy.Keywords: Pitting corrosion; Open circuit corrosion potential; Corrosion test; CSLM studyTribhuvan University Journal Vol. XXVI, No. 1, 2009 Page: 17-26

Effect of Inclusion on Pitting Corrosion of X80 Pipeline Steel

2015 ◽  
Vol 1120-1121 ◽  
pp. 999-1002 ◽  
Author(s):  
Feng Jun Lang ◽  
Xian Qiu Huang ◽  
Tao Pang ◽  
Ying Ma ◽  
Peng Cheng ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Pipeline Steel ◽  
Chloride Ion ◽  
Steel Sample ◽  
Ion Concentration ◽  
Electrochemical Test ◽  
X80 Pipeline Steel ◽  
Atomic Force

The influence of inclusion on pitting corrosion of X80 pipeline steel was investigated by using electrochemical test and atomic force microscope. The results indicated that corrosion potential of X80 pipeline steel sample with higher grade inclusion was lower, and decreased significantly with chloride ion concentration increasing. Inclusion was not conducive to corrosion resistance of X80 pipeline steel. The way of X80 pipeline steel pitting corrosion was that pit formed at the inclusion dissolution, and grew to pitting. There were less corrosion products near the pit hole, forming a cathode ring.

Piping Anti–Corrosion Coating Life Assessment

2014 ◽  
Author(s):  
Bahman Modiri ◽  
Mohammad Pourgol Mohammad ◽  
Mojtaba Yazdani ◽  
Farzad Nasirpouri ◽  
Farzin Salehpour
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Pitting Corrosion ◽  
Probabilistic Analysis ◽  
Reliability Index ◽  
Life Assessment ◽  
Uniform Corrosion ◽  
Analysis Framework ◽  
Internal Corrosion ◽  
Corrosion Mechanisms

The pitting corrosion is influential mechanism in determining life of pipes and coatings. Many researches have been conducted on pitting corrosion in the pipelines, resulting in development of some corrosion models. For internal corrosion, there is one main mechanism and it is the uniform corrosion, because dynamic corrosion occurs inside the pipe. However outside the pipe, two corrosion mechanisms are considered for gas pipelines: i) uniform corrosion and ii) pitting corrosion. Effect of uniform corrosion is less than the pitting corrosion, so just pitting corrosion is investigated. Calculating the depth of corroded area is the most important part in this research. This parameter is calculated with two deferent equations for pitting and uniform corrosion. Monte Carlo simulation is used for sampling and calculation of the reliability index. This index is utilized for estimating of reliability. The extended probabilistic analysis framework is applied to a typical gas pipeline.

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