Corrosion of an AZ31B Magnesium Alloy by Sulfate-Reducing Prokaryotes in a Mudflat Environment

Abstract

To study the abnormal failure of magnesium anodes for buried pipelines in marine engineering in the unique environment of mudflats, a strain of a sulfate–reducing prokaryote (SRP) was isolated from pipe–laying soil, and identified as Desulfovibrio sp. HQM3. Weight–loss test, electrochemical measurements, SEM, EDS, XRD, and CLSM techniques were used to study the effect of corrosion on the AZ31B magnesium alloy. Under the influence of SRP, the magnesium alloy corroded severely at rates up to 1.31 mm/year in the mudflat environment. SRP accelerated corrosion by 0.3mm/year. Pitting occurred on the samples in both abiotic and biotic systems. The pitting depth reached 163.47 μm in the biotic system after 14 days. The main composition of a petal–like corrosion product was Mg(OH)2. The results show that a mudflat environment can lead to an accelerated corrosion of magnesium alloys.

Corrosion Behavior of AZ31B Magnesium Alloy Anode by Sulfate-Reducing Prokaryotes in the Tidal Flat Mud with Different Water Contents

“…We present the conditions, parameters and results of the study of corrosion of different materials by soil water content in Table 8 [29,[51][52][53][54]: It can be found that different researchers have slightly different results on the relationship between water content and corrosion rate.…”

“…HQM3. It was isolated from the tidal flat sediments near the pipeline on the west coast of Dahengqin Island (113.45 • E, 22.12 • N), Zhuhai City, Guangdong Province [29]. Microbial cells were cultured using Postgate C (PGC) medium.…”

“…Three water contents for the tidal flat mud were selected, namely, the mass ratio of mud to water (actually a mixed solution of seawater medium containing 4% SRP concentration) was 6:4, 5:5 and 4:6. The simulated mud water content in this work refers to the actual water content measured for the actual buried pipeline [29]. The number of sessile SRP cells increased significantly with the increase in the water content.…”

Effect of One Sulfate-Reducing Bacterium SRB-Z Isolated from Pearl River on the Corrosion Behavior of Q235 Carbon Steel

“…They have been widely reported to participate in metal corrosion processes and are considered the main kind of bacteria which induce MIC [11][12][13][14][15][16]. They use sulfate as an electron acceptor for anaerobic respiration, producing H 2 S [17][18][19][20][21]. Usually, SRB induces local corrosion of metal.…”