scholarly journals Study on Electrochemical Behavior of 20# Carbon Steel with Disbonded Coating by Scanning Kelvin Probe and Local Electrochemical Impedance Spectroscopy

2020 ◽  
pp. 4988-5001
Author(s):  
Changyou Wang ◽  
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Carbon Steel ◽  
Impedance Spectroscopy ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Local Electrochemical Impedance Spectroscopy ◽  
Disbonded Coating

scholarly journals Electrochemical Behavior of Conventional and Rheo-High-Pressure Die Cast Low Silicon Aluminum Alloys in NaCl Solutions

CORROSION ◽  
10.5006/3254 ◽  
2019 ◽  
Vol 75 (11) ◽  
pp. 1339-1353
Author(s):  
Maryam Eslami ◽  
Flavio Deflorian ◽  
Caterina Zanella
Keyword(s):  
High Pressure ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Behavior ◽  
Anodic Polarization ◽  
Electrochemical Impedance ◽  
Casting Process ◽  
Corrosion Mechanism ◽  
Die Cast ◽  
Polarization Test

The electrochemical behavior of a low silicon aluminum alloy cast by the conventional and rheo-high-pressure die cast processes is evaluated using polarization test and electrochemical impedance spectroscopy in 0.01 M, 0.05 M, 0.1 M, and 0.6 M sodium chloride solutions. Compared to the conventional high-pressure die cast process, rheocasting introduces some alterations in the microstructure including the presence of aluminum grains with different sizes, formed at different solidification stages. According to the results of the anodic polarization test, conventional cast and rheocast samples show similar breakdown potentials. However, the rheocast samples present enhanced oxygen reduction kinetics compared to the conventional cast sample. Based on scanning electron microscopy examinations, localized microgalvanic corrosion is the main corrosion mechanism for both alloys and it initiates at the interface of aluminum with iron-rich intermetallic particles which are located inside the eutectic regions. The corrosion further develops into the eutectic area. Although the rate of the cathodic reaction can be influenced by the semisolid microstructure, according to the results of anodic polarization and electrochemical impedance spectroscopy tests, the corrosion behavior is not meaningfully affected by the casting process.

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