scholarly journals Experimental research of shipbuilding steels at cathodic polarization

2020 ◽  
Author(s):  
А.В. Родькина ◽  
О.А. Иванова ◽  
В.А. Крамарь ◽  
В.Р. Душко
Keyword(s):  
Oxide Film ◽  
Cathodic Protection ◽  
Steel Surface ◽  
Cathodic Polarization ◽  
Mechanical Damage ◽  
Applied Current ◽  
Electrostatic Adsorption ◽  
Rebinder Effect ◽  
Anions And Cations ◽  
Marine Vessels

С целью определения корректных значений защитного потенциала, указываемых в системах катодной защиты морских судов и сооружений наложенным током для предотвращения локальных коррозионно-механических разрушений разработана методика определения потенциала корпусных сталей в отсутствии поверхностной пленки при катодной поляризации. Полученные значения потенциала могут быть рекомендованы для использования как защитного в системах катодной защиты, обеспечивая потенциал незаряженной поверхности стали, в том числе и на поверхности без оксидной пленки. В результате происходит подавление процесса адсорбции анионов и катионов; предотвращение процесса растрескивания стали; стабилизация процесса катодной поляризации при потенциале незаряженной поверхности, когда на поверхности стали заторможена электростатическая адсорбция и не наблюдается эффект Ребиндера. In order to determine the correct values of the protective potential indicated in the cathodic protection of marine vessels and structures by applied current to prevent local corrosion and mechanical damage, a method has been developed for determining the potential of hull steels during cathodic polarization on a surface without an oxide film. The obtained potential values can be recommended for use as protective in cathodic protection, providing the potential of an uncharged steel surface, including on a surface without an oxide film. As a result, the process of anions and cations adsorption is suppressed; prevention of steel cracking; stabilization of the cathodic polarization process at the potential of an uncharged surface, when electrostatic adsorption is inhibited on the steel surface and the Rebinder effect is not observed.

Effects of Cathodic Protection on Cracking of High-Strength Pipeline Steels

2010 ◽  
Author(s):  
M. Elboujdaini ◽  
R. W. Revie ◽  
M. Attard
Keyword(s):  
Hydrogen Embrittlement ◽  
Cathodic Protection ◽  
Cathodic Polarization ◽  
Water Solution ◽  
Reference Electrode ◽  
High Strength ◽  
Point Of View ◽  
Pipeline Steels ◽  
Different Levels ◽  
Reduction Index

A comparison was made between four strength levels of pipeline steels (X-70, X80, X-100 and the X-120) from the point of view of their susceptibility to hydrogen embrittlement under cathodic protection. The main aim was to determine whether the development of higher strength materials led to greater susceptibility to hydrogen embrittlement. This was achieved by straining at 2×10−6 s−1 after cathodic charging in a simulated dilute groundwater solution (NS4) containing 5% CO2/95% N2 (pH approximately 6.7). The results showed quantitatively the loss of ductility after charging, and the loss of ductility increases with strength level of the steel. All four steels exhibited a loss of ductility at overprotected charging potential and an increasing amount of brittleness on the fracture surface. Ductility in solution was measured under four different levels of cathodic protection, ranging from no cathodic protection to 500 mV of overprotection with respect to the usually accepted criterion of −850 mV vs. Cu/CuSO4 reference electrode. Experiments were carried out by straining during cathodic polarization in a simulated dilute ground water solution (NS-4 solution). Strain rates used were 2×10−6 s−1. After failure, the fracture surfaces were characterized by examination using scanning electron microscopy (SEM). Under cathodic protection, all four steels showed loss of ductility and features of brittle fracture. The loss of ductility under cathodic polarization was larger the greater the strength of the steel and the more active (i.e., more negative) the applied potential. The Ductility Reduction Index (DRI) was defined to quantify the reduction in ductility.

Polarization Studies of Aluminum Alloys In Water at 200 C and 300 C

CORROSION ◽  
1963 ◽  
Vol 19 (4) ◽  
pp. 146t-155t ◽  
Author(s):  
J. H. GREENBLATT ◽  
A. F. McMILLAN
Keyword(s):  
Anodic Polarization ◽  
Cathodic Polarization ◽  
Oxidation Potential ◽  
Electronic Conduction ◽  
Film Resistance ◽  
Applied Current ◽  
Weight Gain Data ◽  
Current Densities ◽  
Polarization Studies ◽  
Impressed Current

Abstract Specimens of commercial 2S aluminum and two special alloys containing iron and nickel were polarized anodically and cathodically at a number of different current densities at 200 C and 300 C. Weight gains were obtained and the potentials relative to the stainless steel autoclave were measured by an interrupter method. The weight gain data indicated that the polarizing current is being carried by electronic conduction. The potential-time curves for anodic polarization indicate differences between 2S aluminum and the alloys in that greater polarization is obtained with the latter. These curves also indicate that the impressed current decreases the film resistance. In all cases the potential reached a plateau value with time and this time was shorter for the alloys. The potential-time curves for cathodic polarization also show plateau values but the rise to a plateau value is in the opposite sense to the applied current. With increasing cathodic polarization the plateau values occur at more negative values of the potential. This latter trend is in the same direction as the applied polarizing current. This apparently is explained in terms of the build-up of the aluminum oxidation potential which acts in a sense opposite to the applied current. Again the time to reach plateau values was shorter for the alloys. Voltage current curves were also obtained on specimens left overnight (approximately 17 hours) at two different anodic polarizing currents. These curves indicated differences between 2S aluminum and the alloys; these differences are discussed in terms of the semi-conducting properties of the oxide film. The observations made on the differences in the properties of the oxide films on the materials examined as revealed by potential and polarization curves are discussed as to their significance in determining corrosion resistance.

The influence of liquid Pb–Bi on the anti-corrosion behavior of Fe3O4: a first-principles study

2016 ◽  
Vol 18 (11) ◽  
pp. 7789-7796 ◽  
Author(s):  
Dongdong Li ◽  
Bingyan Qu ◽  
H. Y. He ◽  
Y. G. Zhang ◽  
Yichun Xu ◽  
...  
Keyword(s):  
Oxide Film ◽  
Corrosion Behavior ◽  
First Principles ◽  
Steel Surface ◽  
First Principles Calculations ◽  
First Principles Study

In this work, the influence of Pb and Bi atoms on the anti-corrosion behavior of the oxide film (Fe3O4) formed on steel surface is investigated based on first-principles calculations.

Characterization of steel surface under cathodic protection in seawater

2013 ◽  
Vol 60 (3) ◽  
pp. 160-167 ◽  
Author(s):  
Mariela Rendón Belmonte ◽  
José Trinidad Pérez Quiroz ◽  
Benjamín Valdez Salas ◽  
Miguel Martínez Madrid ◽  
Andrés Torres Acosta ◽  
...  
Keyword(s):  
Cathodic Protection ◽  
Steel Surface

Cathodic Protection of Iron In the Temperature Range 25 C-92 C★

CORROSION ◽  
1958 ◽  
Vol 14 (4) ◽  
pp. 54-56 ◽  
Author(s):  
G. R. HOEY ◽  
M. COHEN
Keyword(s):  
Current Density ◽  
Cathodic Protection ◽  
Cathodic Polarization ◽  
Open Circuit ◽  
Cathodic Current Density ◽  
Oxygen Solubility ◽  
Nacl Solution ◽  
Cathodic Current ◽  
Temperature Range ◽  
Higher Temperature

Abstract The cathodic protection of iron was studied in the temperature range 25 C to 92 C. The limiting protective current density and the open circuit cathodic current density for iron in dilute NaCl solution goes through a temperature maximum at roughly 75 C. This is explained in terms of the effect of decreasing oxygen solubility at the higher temperature on the local cathodic reaction, 2H+ + O2 + 4e = 20H- Iron corrodes under cathodic control at room temperature, whereas at the higher temperatures there is a mixed cathodic-anodic control. Cathodic polarization curves for iron in dilute NaCl solution were obtained in the temperature range 25 C to 92 C. Unsteady potentials were observed in the vicinity of the limiting protective current, whereas at higher and lower currents, steady potentials were observed. The current density at which the potential of the iron reaches —0.5 volt on the hydrogen scale gives satisfactory protection. The nature of the corrosion products of iron is unaffected by temperature in the range studied. 5.2.2

scholarly journals On the Mechanism of Cathodic Protection and Its Implications on Criteria Including AC and DC Interference Conditions

CORROSION ◽  
10.5006/3379 ◽  
2020 ◽  
Vol 76 (5) ◽  
pp. 451-463 ◽  
Author(s):  
Markus Büchler
Keyword(s):  
Present State ◽  
Cathodic Protection ◽  
Steel Surface ◽  
Ph Value ◽  
Underlying Mechanism ◽  
Recent Developments

In recent years, a wide agreement with respect to the processes associated with cathodic protection (CP) has been reached within the CP industry. The increase of the pH value at the steel surface and the generation of passivating conditions as a result of the CP current are widely accepted as the relevant underlying mechanism. Based on this understanding it was possible to identify the relevant processes with respect to AC and DC interference and explain the empirical observations. This led to the development of ISO 18086 and has significantly influenced the work on ISO/DIS 21857. This paper summarizes present state of knowledge, the more recent developments, and their implications with respect to the CP criteria. It summarizes the relevant aspects in association with interference conditions and highlights possible future approaches with respect to the assessment of the effectiveness of CP.

Current Requirement for Cathodic Protection Of Oil Well Casing★

CORROSION ◽  
1957 ◽  
Vol 13 (11) ◽  
pp. 89-96 ◽  
Author(s):  
E. W. HAYCOCK
Keyword(s):  
Cathodic Protection ◽  
Laboratory Experiments ◽  
Scientific Basis ◽  
Oil Well ◽  
Complete Protection ◽  
Applied Current ◽  
Galvanic Cells ◽  
Current Requirement ◽  
Economic Balance ◽  
Current Potential

Abstract Methods at present used to indicate the minimum applied current required to give complete cathodic protection are discussed and evaluated in terms of their scientific basis and their applicability to the protection of oil well casing. Laboratory experiments are described involving the application of cathodic protection currents to a series assembly of galvanic cells. The results of these experiments lead to a modification of the log current—potential criterion of complete protection widely used at the present time. The experiments also indicate the amount of corrosion repressed as a function of the applied protection current, information which is of considerable value when an economic balance is involved. 5.2.4

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