Yesen Zhu, Taoyong Hu, Yujie Li, Junhua Hao, Bin Han and Quan Yuan
The aim of this paper is to construct a device that simulated the seawater splash zone, dynamic waterline zone (splash zone) and full immersion zone. Localized corrosion of 2A12…
Abstract
Purpose
The aim of this paper is to construct a device that simulated the seawater splash zone, dynamic waterline zone (splash zone) and full immersion zone. Localized corrosion of 2A12 aluminum alloy long-scale specimen was studied.
Design/methodology/approach
Corrosion morphologies before and after the corrosion product removal were used to identify corrosion intensity at full seawater immersion zone, dynamic waterline zone (splash zone) and atmospheric zone. The average depth and diameter of corrosion pits in the three zones were evaluated by three-dimensional optical microscopy. The impact of wetting time of the atmospheric zone on the localized corrosion was investigated.
Findings
Corrosion pits were observed on the surface on day 4 for the wetted atmospheric zone (Case 1), and on the surface on day 8 for the alternant wet/dry atmospheric zone (Case 2). The corrosion product layer on the surface for Case 1 was partially broken down while the layer on the surface for Case 2 was intact. Average pitting depth and pitting diameters for Case 1 were more serious than that for Case 2.
Originality/value
The above findings revealed that the humidity of the atmospheric zone had great impact on the localized corrosion of aluminum alloy at the seawater splash zone.
Details
Keywords
Yesen Zhu, Cheng-Qing Gu, Jinliang Wang, Xiaohui Xi and Zhenbo Qin
The purpose of this paper is to study the effect of chromium content on the microstructure and corrosion resistance of Ni-Cr coating.
Abstract
Purpose
The purpose of this paper is to study the effect of chromium content on the microstructure and corrosion resistance of Ni-Cr coating.
Design/methodology/approach
Ni-Cr coating was prepared by pulse current electrodeposition with trivalent chromium. On the basis of studying effect of electroplating parameters on composition and morphology, Ni-Cr alloy coatings with various chromium contents were obtained. The microstructure was characterized by scanning electron microscopy, X-ray diffractometer and transmission electron microscopy. Corrosion behavior was studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques.
Findings
Electrodeposited chromium was solidly dissolved in nickel and refined the grain of the coating. With the increase of Cr content, the corrosion resistance of Ni-Cr coating was enhanced, which is due to the formation of continuous nickel hydroxide and compact chromium oxide passive films.
Originality/value
Ni-Cr alloy coating without penetration crack was prepared in trivalent chromium electrolyte, and the mechanism of its excellent corrosion resistance was proposed.
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Keywords
Yesen Zhu, Zhe Liu, Zhenbo Qin, Mengyang Hou, Taoyong Hu and Quan Yuan
The purpose of this paper is to study the cavitation erosion stages of AA5083 by electrochemical noise (EN).
Abstract
Purpose
The purpose of this paper is to study the cavitation erosion stages of AA5083 by electrochemical noise (EN).
Design/methodology/approach
EN technology including noise resistance and fast Fourier transform were used to characterize the electrochemical process during the cavitation erosion process.
Findings
AA5083 suffers from uniform corrosion during the cavitation erosion process. The whole cavitation erosion process can be divided into three stages: incubation stage, acceleration stage and steady-state stage. EN signals showed obvious differences in different stages of cavitation erosion.
Originality/value
EN technique is a suitable method that can be used to study cavitation erosion mechanism and identify cavitation erosion stages.