scholarly journals Development of Electrochemical Surface Treatment to Visualize Critical Corrosion-Inducing Inclusions of Zr in Chloride Environments

2021 ◽  
Author(s):  
Tomoyo MANAKA ◽  
Yusuke TSUTSUMI ◽  
Peng CHEN ◽  
Maki ASHIDA ◽  
Hideki Katayama ◽  
...  
Keyword(s):  
Surface Treatment ◽  
Cathodic Polarization ◽  
Initiation Site ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Corrosion Initiation ◽  
Surrounding Matrix ◽  
Corrosion Pit ◽  
Electrochemical Surface Treatment ◽  
Zr Alloy

Abstract An electrochemical surface treatment was developed to visualize the corrosion-inducing inclusions of Zr in chloride environments. Pure Zr and Zr alloy (Zr-0.5O-0.5C) were evaluated in this study. The electrochemical surface treatment consisted of repeated galvanostatic anodic polarization and potentiostatic cathodic polarization. After the electrochemical surface treatment, only one brittle and non-conductive shell of Zr oxide was observed at the corrosion initiation site on the tested surface. The corrosion-inducing inclusions were found inside the corrosion pit under the optimum polarization conditions. At the corrosion initiation site on pure Zr, the area inside the corrosion pit contained larger amounts of O, C, and Si than the surrounding matrix. In the case of the Zr-0.5O-0.5C alloy, relatively larger inclusions were observed after the treatment. Extremely large amounts of Si, together with O and C, were present in the inclusions. The inclusions that induced localized corrosion on the pure Zr and Zr-0.5O-0.5C specimens were found to be precipitated, involving the specific aggregation of Si. The surface treatment developed in this study is expected to be utilized as a powerful tool to elucidate the localized corrosion mechanism of Zr in chloride environments.

Development of Electrochemical Surface Treatment for Improvement of Localized Corrosion Resistance of Zirconium in Chloride Environment

2020 ◽  
Vol 69 (11) ◽  
pp. 307-314
Author(s):  
Tomoyo Manaka ◽  
Yusuke Tsutsumi ◽  
Maki Ashida ◽  
Peng Chen ◽  
Hideki Katayama ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Surface Treatment ◽  
Localized Corrosion ◽  
Chloride Environment ◽  
Electrochemical Surface Treatment

Porosity Quatification of Cast Aluminium Alloys on Machined Surfaces Using Metallography and Eddy-Currents

2015 ◽  
Vol 647 ◽  
pp. 188-194
Author(s):  
Břetislav Skrbek
Keyword(s):  
Surface Treatment ◽  
Aluminium Alloys ◽  
Eddy Currents ◽  
Initiation Site ◽  
Cast Aluminium ◽  
Strength And Ductility ◽  
Machined Surfaces

The porosity is unwanted phenomenon mostly that is tried to eliminate. The pores are initiation site of fatigue fractions usually, they worse strength and ductility of materials, quality of machined surfaces and their following surface treatment.

Ranking of metallic and non-metallic coatings in the electrochemical surface treatment sector

2021 ◽  
pp. 54-58
Author(s):  
E. G. Vinokurov ◽  
T. F. Burukhina ◽  
I. S. Kuroshev
Keyword(s):  
Surface Treatment ◽  
Correlation Coefficient ◽  
The United States ◽  
Critical Value ◽  
Electrochemical Methods ◽  
Metallic Coatings ◽  
Metal Coatings ◽  
Technical Research ◽  
Priority Areas ◽  
Electrochemical Surface Treatment

The distribution of coatings by the frequency of their application during surface treatment by electrochemical methods is considered. This is important not only for understanding the structure of the electrochemical surface treatment sector, but also for identifying priority areas of scientific and technical research. Nonparametric statistical methods show the uniformity of samples and reveal the relationship between the number of enterprises that sell a certain type of coating, i.e. the frequency of applying a certain type of coating in different countries (USA, Japan, Italy, France, Germany, Great Britain, Spain, Canada, Mexico, Russia, South Africa). The results of testing the hypothesis of a close relationship between the ranks of coatings showed that a significant correlation was found between the distribution of coatings by the frequency of their application (implementation) among all countries. For example, when comparing the United States and Canada, the rank correlation coefficient is 0.62 (the lowest value obtained), which is greater than the calculated critical value of 0.56; when comparing Italy and Spain, the correlation coefficient takes the highest value of 0.97, which is greater than the critical value of 0.19. The results obtained allowed us to use this data to compile a generalized rating of the frequency of use of all coatings based on data from different countries. Based on the analysis, metal coatings can be arranged in a row according to the descending frequency of their application: Cr > Ni > Zn > Cu > Cd. The results of the ranking of coatings showed that the most commonly used electrochemical methods for surface treatment are metal coatings with chromium and nickel, and among the inorganic non – metallic coatings-oxide and then phosphate, which allows us to highlight the research devoted to the application of these coatings as priority areas of scientific and technical research.

scholarly journals Corrosion of Carbon Steel in Artificial Geothermal Brine: Influence of Carbon Dioxide at 70 °C and 150 °C

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3801 ◽  
Author(s):  
Gabriela Aristia ◽  
Le Quynh Hoa ◽  
Ralph Bäßler
Keyword(s):  
Carbon Dioxide ◽  
Carbon Steel ◽  
Temperature Effect ◽  
Electrochemical Impedance ◽  
Corrosion Products ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Sem Images ◽  
Geothermal Brine ◽  
Corrosive Effect

This study focuses on the corrosion mechanism of carbon steel exposed to an artificial geothermal brine influenced by carbon dioxide (CO2) gas. The tested brine simulates a geothermal source in Sibayak, Indonesia, containing 1500 mg/L of Cl−, 20 mg/L of SO42−, and 15 mg/L of HCO3− with pH 4. To reveal the temperature effect on the corrosion behavior of carbon steel, exposure and electrochemical tests were carried out at 70 °C and 150 °C. Surface analysis of corroded specimens showed localized corrosion at both temperatures, despite the formation of corrosion products on the surface. After 7 days at 150 °C, SEM images showed the formation of an adherent, dense, and crystalline FeCO3 layer. Whereas at 70 °C, the corrosion products consisted of chukanovite (Fe2(OH)2CO3) and siderite (FeCO3), which are less dense and less protective than that at 150 °C. Control experiments under Ar-environment were used to investigate the corrosive effect of CO2. Free corrosion potential (Ecorr) and electrochemical impedance spectroscopy (EIS) confirm that at both temperatures, the corrosive effect of CO2 was more significant compared to that measured in the Ar-containing solution. In terms of temperature effect, carbon steel remained active at 70 °C, while at 150 °C, it became passive due to the FeCO3 formation. These results suggest that carbon steel is more susceptible to corrosion at the near ground surface of a geothermal well, whereas at a deeper well with a higher temperature, there is a possible risk of scaling (FeCO3 layer). A longer exposure test at 150 °C with a stagnant solution for 28 days, however, showed the unstable FeCO3 layer and therefore a deeper localized corrosion compared to that of seven-day exposed specimens.

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