摘要
目的通过实验模拟硫酸盐还原菌(SRB)对镍磷基镀层的腐蚀行为,探究SRB对N80钢、Ni-P及Ni-P/Ni-Cu-P复合镀层的腐蚀过程及差异。方法采用连续化学镀工艺在N80钢基体上制备了Ni-P/Ni-Cu-P复合镀层。通过生物培养技术、静态挂片实验及电化学测试探究了镀层及N80钢在SRB环境下的腐蚀行为,结合NaS2O3滴定技术、SEM、XRD、XPS等分析手段,对不同膜层的腐蚀行为和差异进行表征分析。结果在浸泡腐蚀14 d后,N80钢腐蚀速率为0.0491 mm/a,Ni-P镀层约为0.0269 mm/a,Ni-P/Ni-Cu-P复合镀层为0.0051mm/a。含铜复合镀层环境中的SRB生长数量及S2-含量始终低于其他试样组,并缩短了SRB的生长周期。对比样N80钢和Ni-P单镀层表面均出现明显的点蚀坑,而复合镀层试样表面较光滑、平整,未发现明显孔洞。随着腐蚀的进行,N80钢和Ni-P镀层的阻抗先增加后减少,与SRB生长规律一致,而复合镀层的阻抗依次降低,并未受SRB数量生长的影响。结论Ni-P/Ni-Cu-P复合镀层较低的孔隙率、较高的接触角,降低了SRB细菌的吸附;此外,Cu离子从合金表面释放进入溶液或SRB体内,破坏了SRB的细胞膜、细胞壁使其结构受损,降低了体系SRB活性;同时复合镀层的高磷非晶结构和致密的表层钝化膜极大地阻碍了离子和电子的进出,增加了膜层阻力,导致Ni-P/Ni-Cu-P复合镀层在SRB和地层水的混合溶液中具有极低的腐蚀速率和较低的点蚀概率。
To improve the corrosion resistance of carbon steel against microorganisms,the corrosion behavior of sulfate-reducing bacteria(SRB)on nickel-phosphorus coatings is simulated by experiment,and the corrosion process and differences of SRB on N80 steel,Ni-P and Ni-P/Ni-Cu-P composite coatings are investigated.Ni-P/Ni-Cu-P composite coatings are prepared on the N80 steel substrate using continuous chemical plating process.The corrosion behavior of the coatings and N80 steel in the SRB environment is investigated by biological culture technology,static hanging experiments,and electrochemical tests.Combined with NaS2O3 titration technology,SEM,XRD,and XPS analysis methods are used to characterize and analyze the corrosion behavior and differences of different coating layers.As a result,in terms of coating preparation performance,the surface structure of the Ni-P/Ni-Cu-P composite coatings is more delicate,uniform and dense.No obvious pinholes or defects are found on the surface under 1000 times magnification,and the surface contact angle is large,which plays a role of hydrophobicity.At the same time,the porosity is very low,only 0.4 N/cm2.After immersion corrosion for 14 days,the corrosion rate of N80 steel is 0.0491 mm/a,that of the Ni-P coatings is approximately 0.0269 mm/a,and that of the Ni-P/Ni-Cu-P composite coatings is 0.0051 mm/a.The number of SRB growths and S2–content in the copper-containing composite coating environment is consistently lower than those in other sample groups,significantly shortening the SRB growth cycle.The samples of N80 steel and Ni-P single coating surfaces show obvious pitting corrosion,while the composite coating samples have a smoother and flatter surface with no significant voids observed.As corrosion progresses,the impedance of N80 steel and Ni-P coatings first increases and then decreases,consistent with the SRB growth pattern,whereas the impedance of the composite coatings sequentially decreases without being affected by the number of SRBs.Comparing the XRD spectra of the composite coatings before and after corrosion,the Ni-P/Ni-Cu-P composite coatings show a significant shift in the diffraction angles and a narrowing of the peak shapes,indicating a decrease in lattice constant.Since the atomic radius of Cu filling the 4s orbital is larger than that of Ni,this suggests that Cu diffuses or migrates from the Ni-Cu solid solution,leading to a phase transformation during the corrosion process.The Ni-P/Ni-Cu-P composite coatings have a lower porosity and higher contact angle,which reduces the adsorption of SRB bacteria;furthermore,Cu ions are released from the alloy surface into the solution or within the SRB cells disrupt the cell membrane and cell wall,causing structural damage to SRB bacteria,leading to noticeable shrinkage,damage,and leakage of cellular contents,thereby reducing the activity of the SRB system and accelerating microbial degradation.At the same time,Ni-Cu-P belongs to the anodic coating,forming a structure with a large anode and a small cathode compared with the inner Ni-P coating,which is relatively safe and reduces the anodic dissolution rate,preventing damage to the composite structure's surface in the short term.Consequently,the longitudinal corrosion of the coating becomes transverse corrosion,delaying the penetration of corrosion to the entire coating layer and sacrificing the top layer to protect the bottom layer,thereby delaying substrate corrosion.Moreover,the high phosphorus amorphous structure and the dense surface passive film of the composite coating significantly hinder the entry and exit of ions and electrons,increasing the film resistance,resulting in extremely low corrosion rates and low pitting probabilities for Ni-P/Ni-Cu-P composite coatings in mixed solutions of SRB and formation water.
作者
张雅妮
张成鑫
宋伟
段博文
刘波
樊冰
王思敏
ZHANG Yani;ZHANG Chengxin;SONG Wei;DUAN Bowen;LIU Bo;FAN Bing;WANG Simin(School of Materials Science and Engineering,Xi'an Petroleum University,Xi'an 710065,China;CNPC Engineering Materials Research Institute Co.,Ltd.,Xi'an 710077,China;Shougang Group Changzhi Iron and Steel Co.,Ltd.,Shanxi Changzhi 046031,China)
出处
《表面技术》
北大核心
2025年第12期72-84,共13页
Surface Technology
基金
国家自然科学基金(52401111)
陕西省自然科学基础研究计划项目(2024JC-YBQN-0457)
西安市科技计划项目(24GXFW0075)。
