Study on mechanism underlying the acceleration of pitting corrosion of B30 copper-nickel alloy by sulfate-reducing bacteria in seawater

Jian Wang; Huan Li; Min Du; Mingxian Sun; Li Ma

doi:10.1016/j.scitotenv.2024.172645

Study on mechanism underlying the acceleration of pitting corrosion of B30 copper-nickel alloy by sulfate-reducing bacteria in seawater

Sci Total Environ. 2024 Jun 10:928:172645. doi: 10.1016/j.scitotenv.2024.172645. Epub 2024 Apr 20.

Authors

Jian Wang¹, Huan Li¹, Min Du², Mingxian Sun³, Li Ma³

Affiliations

¹ The Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China.
² The Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China. Electronic address: ssdm99@ouc.edu.cn.
³ State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research Institute (LSMRI), Qingdao, China.

PMID: 38643520
DOI: 10.1016/j.scitotenv.2024.172645

Abstract

In this paper, the relationship between the pitting corrosion formation of B30 copper-nickel (CuNi) alloy and the metabolism of sulfate-reducing bacteria (SRB) was investigated. Combined with the influence of temperature during the actual operation of the cooling systems, the evolution law of the alloy passivation film was analyzed, and the mechanism of SRB promoting the accelerated development of B30 CuNi alloy pitting corrosion was revealed. The results show that SRB significantly promoted the pitting formation and development of B30 CuNi alloy. The maximum pitting depth was 3.9 μm in the sterile system and 15.3 μm with SRB, which was 3.9 times higher than that of sterile system. The loose porous Cu₂S film formed by SRB metabolites and copper matrix was easily penetrated by corrosive anions, which promoted copper dissolution and led to pit nucleation. The sulfide adsorbed on the surface prevented or delayed the passivation of B30 CuNi alloy by blocking the adsorption site of O atom, and the corrosion nuclei continued to grow. The non-uniformity caused by the film peeling accelerated the longitudinal development of pitting corrosion, and the expansion and coalescence of adjacent pits caused the transverse development of pitting corrosion. Temperature had a certain influence on the SRB and the formation of B30 CuNi alloy passivation film. The passivation film was formed rapidly at 50 °C with poor quality and the passivation property of Cu₂O film was weakened. With the increase of temperature, the pitting potential of sterile system negative shifted from 0.447 to 0.360 V (vs. SCE), while SRB system from 0.340 to 0.198 V (vs. SCE), and the pitting resistance decreased. The passivation film with defects and the Cu₂S reduced the barrier efficiency of the film and accelerated the pitting corrosion of B30 CuNi alloy.

Keywords: Acceleration; B30 copper–nickel alloy; Metabolite; Pitting corrosion; Sulfate-reducing bacteria; Temperature.