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This paper aims to investigate the galvanic corrosion of titanium/L 316 stainless steel, by electrochemical noise (EN), electrochemical impedance spectroscopy (EIS), and anode/cathode area ratio effect on the galvanic behavior of the couple.

The EN measurement was employed to examine effects of anode to cathode area ratio on the galvanic corrosion behavior between stainless steel L 316 and titanium in artificial seawater. Current noise and potential noise were monitored simultaneously using a three‐electrode configuration under open‐circuit condition. The noise resistance was evaluated as the ratio of the standard deviation of the potential to that of the current noise after removing the DC component. The time‐series noise patterns were transformed into frequency domain by fast Fourier transformation and then their power spectrum densities (PSDs) at specified frequency were determined and compared with the EIS and polarization results.

The EN, EIS and polarization results were in agreement. Galvanic corrosion density increase and galvanic potential moved slowly to negative direction with decrease in anode/cathode area ratio. The results showed that the slope of PSD of the current (i.e the “roll off”) was rising slowly where the anode/cathode area ratio was declined. The relationship between polarization resistance (Rp) and noise resistance (Rn) was investigated. Rt was determined by EIS for samples, and its value compared with Rp and Rn. The result indicates that galvanic corrosion has an inversely relation with anode/cathode area ratio that exposed to aggressive environment.

This paper presents the application of noise analysis to demonstrate galvanic corrosion and the effect of area ratio anode/cathode on current density and galvanic potential.

The purpose of this study is to provide a theoretical basis for the study of the galvanic corrosion mechanism of copper coupled silver-coating under a thin electrolyte layer in electronic systems.

Electrochemical measurements and surface characterizations.

The results indicate that the potential difference between copper and silver electrodes first quickly increases, and then reaches a relatively stable and large value with the extension of the immersion time. With the significant increase in the cathode/anode area ratio in electronic systems, the area ratio effect obviously accelerates the corrosion of copper due to the remarkable promotion of the cathode process. For a large cathode/anode area ratio, the galvanic current density always maintains a large value and exhibits an increasing trend with the extension of the immersion time, which is attributed that the area ratio effect reduces the protection of corrosion products. For the same area of cathode and anode, the galvanic current density always maintains a small value with the extension of the immersion time due to a low galvanic effect and protective corrosion products.

This work provides some information for the establishment of reliably protective measures for electronic systems in service.

This work not only provides some information for the establishment of reliably protective measures for electronic systems in service, but also provides a theoretical basis for the selection of metal materials in microelectronic systems.

This work provides not only a theoretical basis for the study of the galvanic corrosion mechanism of Cu/Ag under a thin electrolyte layer, but also provides some information for the establishment of reliably protective measures for electronic systems in service.

The purpose of this paper is to focus on the galvanic corrosion behaviors of the low-carbon ferritic stainless steel electrical resistance welding (ERW) joint in the simulated seawater.

The electrochemical methods such as electrochemical noise, galvanic current and TOEFL polarization curve tests were used to study the galvanic corrosion behaviors of ERW joints of low-carbon ferritic stainless steel in simulated seawater. On this basis, a reliable accelerated corrosion method was developed.

The corrosion type of the base metal and joint is the typical local corrosion. The order of corrosion resistance from strong to weak is: weld zone > base metal > low-temperature heat-affected zone (HAZ) > high-temperature HAZ. The results of constant current-constant potential accelerated corrosion test show that after constant current-constant potential accelerated corrosion, the joints present a typical groove corrosion pattern. The groove initiating area is located in the HAZ, and the corrosion degree in the weld zone is relatively light, which is consistent with the electrochemical test results.

This paper has clarified the galvanic corrosion behaviors of low-carbon ferritic stainless steel ERW joints. Moreover, a reliable accelerated corrosion method for the low-carbon ferritic stainless steel ERW joint has been developed.

The purpose of this paper is to illustrate the complex nature of galvanic corrosion and how it is affected by various key factors related to material characteristics and material processing parameters. In particular, this study aims to explore the effect of pH and temperature on the integrity of a system galvanically protected through the use of zinc anodes.

This study involved electrochemical testing at 24, 35 and 50°C in acidic and neutral solutions. As the environmental temperature and pH change the corrosion potential, galvanic potential and galvanic current may alter. This could influence the expected life of an anode used to protect processing equipment. Accordingly, the experimental design methodology involved collection of corrosion potential, galvanic current and galvanic potential data for zinc and zinc coupled to steel. This information was then used to calculate the life of zinc anodes at different temperatures and pH.

Results indicate that changes in pH and temperature can influence the potential of zinc, the galvanic current in a steel couple and the galvanic potential of zinc joined to steel. Calculations based on the accumulation of these data have revealed that at constant pH as the temperature was decreased, the driving potential of the zinc increased. Through further analysis, it was found that as a consequence of changes in driving potential the integrity of a structure may be put at risk due to fluctuations in pH and temperature.

Practically the research can help predict whether the integrity of a structure protected by zinc sacrificial anodes is at risk depending upon changes in pH and temperature.

Previous work was related mainly to galvanic corrosion at one particular pH and temperature. In this investigation, a range of pH and temperature values was used for the application of zinc anodes. The paper will be of value to engineers involved in the design of cathodic protection systems for oil field equipment, where changes in the acidity of the environment may occur due to differing levels of CO₂ and H₂S entering a structure.

This paper aims to report an experimental investigation of the galvanic corrosion that occurs between the base metal and the welds in X52 carbon steel petroleum pipelines when exposed in carbon dioxide (CO₂)-containing saltwater at pH 4 at room temperature. The pipeline was fabricated by electric resistance welding (ERW).

The experimental setup was a closed glass cell equipped with a silver/silver chloride (Ag/AgCl) reference electrode, two working electrodes (the weld metal and the parent steel specimens) and a gas bubbler. The corrosion potential and polarization resistance of the base metal and the weld were determined using electrochemical testing methods: potentiodynamic polarization scans and linear polarization resistance measurement. The galvanic currents of the base metal when coupled to the weld metal were measured using zero resistance ammetry.

The weld metal was the anode of the couple for a very short time at the beginning of the experiment and then became the cathode until the end of the experiment. This indicates that electric resistance welded X52 steel pipe is a promising material to be operated in CO₂-containing saltwater at pH 4 and 25°C because the weld area is cathodic to the parent metal, the value of the galvanic current is very low (in the order of nanoamps) and the area of the anode (i.e. the parent metal) is significantly larger than that of the cathode (weld metal).

Further experimental research could be performed to investigate the galvanic corrosion behavior between the parent metal and the weld area of X52 carbon steel petroleum pipelines in CO₂-containing saltwater at different pH values, temperature and velocity.

Electric resistance welded X52 steel pipe is a promising material for use with CO₂-containing saltwater environments at pH 4 and 25°C.

The new information presented in the paper is the galvanic corrosion behavior between the parent metal and the ERW weld metal of X52 carbon steel in CO₂-containing solutions. The paper should be useful to researchers working in the field of oil industry corrosion.

In this study, corrosion behavior of X53CrMnNiN219 austenitic stainless steel (SS) and X45CrSi93 martensitic SS, as well as the galvanic corrosion produced by coupling of these dissimilar alloys, are evaluated in a 3.5 Wt.% NaCl solution at temperature 25°C ± 1°C.

The corrosion parameters were estimated through a series of electrochemical tests, including Tafel polarization, electrochemical impedance spectroscopy (EIS), and zero-resistance ammeter (ZRA) technique.

The results of polarization measurements indicate that the value of corrosion current in the galvanic pair is slightly higher than that of both the austenitic and martensitic SS during the initial time of immersion in the chloride solution, which is an indication of compatibility of members in the couple. The galvanic current density measured by ZRA technique shows negative values throughout the test; accordingly, the martensitic SS acts as anode of the pair and corrodes preferentially. Localization index values are limited to the mixed corrosion process, showing relative susceptibility of the martensitic alloy to the uniform and localized corrosion (pitting) due to chloride ions.

The originality is the evaluation of galvanic corrosion susceptibility of X53CrMnNiN219 and X45CrSi93 SSs in chloride solution by the various electrochemical methods consisting of Tafel polarization, EIS, and (ZRA) technique. To our knowledge, no work has been reported on this issue for these chemical compositions under this condition up to now.

The aim of this investigation was to compare the performance of three typical oil field carbon dioxide corrosion inhibitors in controlling preferential weld corrosion (PWC) of X65 pipeline steel in artificial seawater (3.5 weight per cent) saturated with carbon dioxide at one bar pressure.

A novel rotating cylinder electrode (RCE) apparatus was used to evaluate the effect of flow on the inhibition for the weld metal (WM), heat-affected zone (HAZ) and parent material. To fulfill this objective, the galvanic currents flowing between the weld regions were recorded using parallel zero-resistance ammeters, and the self-corrosion rates of the couples were obtained by linear polarization resistance measurements.

The results showed that when 30 ppm of green oil field inhibitors were present in the service environment, a current reversal took place, resulting in accelerated weld corrosion. At high shear stress, the currents increased and further reversals occurred. The inhibitors were more effective in controlling the self-corrosion rates of the parent material than of the WM and HAZ material. It was concluded that PWC was caused by unstable conditions in which the inhibitor film was selectively disrupted from the WM and HAZ, but remained effective on the parent material.

Electrochemical corrosion rate measurements were carried out using an RCE produced from the different regions of the weld. An advantage of using the RCE is that the hydrodynamic conditions are very well defined, and it is feasible to translate the conditions that are known to exist in a production pipeline to those used in laboratory tests.

The purpose of this paper is to study the corrosion of the coupling of two different types of stainless steel, austenitic and ferritic, used in the fabrication of water reservoirs in the solar energy industry.

Potentiodynamic polarization and gravimetric immersion tests were used to evaluate corrosion of the coupling of two different types of stainless steel, austenitic and ferritic.

The galvanic corrosion was not significant in the case of the coupling of AISI 304 and 444 steels. The difference of the open circuit potentials obtained for the AISI 304 and AISI 444 steels was 28 mV for the polished samples. The galvanic current density (i_g) was 55 nA/cm². The corrosion observed in the stainless steel couple was in the weld area.

The methodology used is adequate to evaluate generalized galvanic corrosion. The problem of the corrosion in the coupling of the stainless steels is a problem of localized corrosion and the observed 28 mV potential difference was lower than the dispersion of results usually obtained from readings of corrosion potentials in electrochemical cells.

The use of two different types of steel in contact with each other may lead to galvanic corrosion, and the welding of steel pieces may lead to several corrosion problems. Since the boiler may be used in different countries, subject to a great diversity of water quality, corrosion may be a significant problem.

Literature data of the AISI 444 steel corrosion behaviour are still scarce. The coupling of two different stainless steels (AISI 304 and 444) in the water reservoir manufacturing was a necessary requirement of the solar energy industry. The manufacturers of boilers must evaluate and quantify the corrosion processes, which occur in the equipment used in the solar energy industry. As the solar energy industry has matured in the last ten years, the corrosion of this equipment may be a significant problem in due course.

To provide a summary of research work carried out mainly in the authors' group for evaluating various protective coatings including rustproofing oils, and also for studying corrosion inhibitors using the wire beam electrode (WBE) method.

A range of published papers published during the past 15 years was summarised and reviewed. Recent research work in the authors' group was also included, which involved the combined use of the WBE with electrochemical noise analysis and the scanning reference electrode technique.

The WBE method has been developed into a very useful tool of evaluating the performance of coatings and inhibitors. In particular, The WBE is uniquely applicable for determining the performance of coatings and inhibitors to control localised corrosion.

Focusing mainly on recent research.

A useful source of information for researchers and graduate students working in the areas of organic coating and inhibitor research.

The first summary or review on this research topic.

To study the corrosion behavior of pipeline steel in coastal areas, a tidal seawater macro-cell corrosion device was built using a cycle soaking tank and a macro-cell corrosion facility to simulate the corrosion behavior of pipeline steel in a simulated coastal environment (dry and wet alternations during seawater-soil corrosion macro-cell processes).

The corrosion behaviors were studied via the weight loss method, electrochemical methods and morphological observations on corrosion.

The results show that during the initial stage of tidal seawater/soil macro-cell corrosion process of the X65 steel, the working electrode on the seawater side is the anode of the macro-battery. As corrosion progresses, the anode and the cathode of the macro-battery become inverted. As the area ratio and the dry – wet ratio increase, the time of anode and cathode inversion shortens. Galvanic current density decreases as the dry – wet ratio increases and increases as the area ratio increases. The corrosion process of macro-cell is affected by the reversal of anode and cathode. After the reversal of anode and cathode, the corrosion rate is mainly controlled by dry – wet alternating corrosion.

The corrosion behavior of a pipeline steel in a coastal environment was studied using a tidal seawater macro-cell corrosion device. The synergism effect between the tidal seawater and seawater-soil macro-cell on corrosion behavior was clarified.