Cailiao Baohu (Jul 2022)

Study on Corrosion Characteristics of New Mg - Al Alloy Sacrificial Anode under DC Interference

  • WANG Ai - ling, DANG Mei - ju, LIU Yu - hui, YU Dong - liang, TANG Lei, CUI Gan, LIU Jian - guo, LI Zi - li

DOI
https://doi.org/10.16577/j.issn.1001-1560.2022.0191
Journal volume & issue
Vol. 55, no. 7
pp. 110 – 118

Abstract

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Considering that the pipelines in the southwest mountainous area are faced with an enviornment having the characteristics of large soil resistivity and DC stray current interference, a new type of magnesium aluminum alloy sacrificial anode, in which the aluminum content was up to 5%, was designed. As the sacrificial anode current efficiency was susceptible to Cl- concentration, in order to characterize the applicability of the sacrificial anode in complex soil environments, the corrosion characteristics of the new magnesium aluminum alloy sacrificial anode under different DC potentials and chloride ion concentrations were analyzed by an indoor electrochemical test method. Results showed that with the increase of DC potenital (0～5 V), the positive deviation of the open circuit potential of sacrificial anode increased, indicating that the DC potential promoted the corrosion reaction rate of sacrificial anode and reduced its service life. However, compared with the corrosion rates in the cases of 1 V and 5 V DC potential, the corrosion rate was smaller under the condition of 3 V DC potential. This was attributed to the coverage of sacrificial anode by the corrosion product formed on its surface. With the increase of Cl- concentration (0～0.5 mol/L), the offset degree of open - circuit potential of sacrificial anode increased obviously, and the influence of the Cl- on the performance of sacrificial anode grew with the increase of its concentration. Compared with the current efficiency of the traditional magnesium anode, the current efficiency of the new Mg - Al anode was increased by 40% in high chlorine - containing environment with a DC interference, as the Mg - Al galvanic cell formed in the anode greatly promoted the anode reaction process.

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