Corrosion behavior of B10 copper-nickel alloy beneath a deposit caused by sulfate-reducing bacteria with carbon source starvation in marine environments

海洋环境中沉积物下硫酸盐还原菌有机碳源饥饿条件下引起的B10铜镍合金腐蚀行为

Copper-nickel alloys can suffer severe localized corrosion in marine environments containing sulfate-reducing bacteria(SRB),but the effect of SRB on the under-deposit corrosion of copper-nickel alloys is unknown.In this work,the corrosion behavior of B10 copper-nickel alloy beneath a deposit caused by SRB with carbon source starvation in artificial seawater was studied based on electrochemical measurements and surface analysis.Results demonstrate that SRB with an organic carbon starvation can survive in artificial water but most SRB cells have died.The survived SRB cells can attach to the bare and deposit-covered B10 copper-nickel alloy,leading to the corrosion acceleration.Due to the limitation of organic carbon source,the pitting corrosion of B10 copper-nickel alloy caused by SRB is not serious.However,serious pitting corrosion of the deposit-covered B10 copper-nickel alloy can be found both in abiotic and biotic conditions,and the pitting corrosion and uniform corrosion are further accelerated by SRB.There is a galvanic effect between the bare and deposit-covered specimens in the presence of SRB in the early stage but the galvanic effect after 5 d of testing can be neglected due to the low OCP difference values.

海洋环境中微生物对金属材料的破坏性极强,是导致装备材料腐蚀失效的重要原因之一。海洋环境中耐蚀性较好的铜镍合金在硫酸盐还原菌作用条件下常常发生严重的局部腐蚀,导致铜镍合金设备穿孔失效。沉积物也是造成金属材料局部腐蚀的主要原因之一,然而关于硫酸盐还原菌对铜镍合金沉积物下的腐蚀行为影响缺乏相关研究。本文采用电化学测试方法结合表面分析手段,研究了海洋环境中硫酸盐还原菌在有机碳源饥饿条件下引起的B10铜镍合金沉积物腐蚀行为和机制,为海洋环境中沉积物下的铜镍合金微生物腐蚀控制提供理论指导。研究结果表明,在有机碳源饥饿条件下大部分硫酸盐还原菌都已经死亡,但是部分幸存的硫酸盐还原菌依旧可以在裸的和沉积物覆盖下的B10铜镍合金表面附着和形成生物膜,从而加速B10铜镍合金的腐蚀。受到有机碳源的限制,硫酸盐还原菌导致的点蚀较为轻微。但是无论是在有无细菌存在的条件下,沉积物下的B10铜镍合金都遭受了较为严重的点蚀,而且在硫酸盐还原菌存在条件下点蚀更为严重。在含有硫酸盐还原菌的生物体系中,裸的和沉积物覆盖下的B10铜镍合金在早期有一个明显的电偶效应,但是在5 d之后,由于较小的开路电位差而导致的电偶效应几乎可以忽略。因此,沉积物下硫酸盐还原菌导致的铜镍合金腐蚀必须引起关注。