L245钢及Ni-W合金镀层在碱性硫化钠溶液中的腐蚀行为研究

Research on the Corrosion Behaviors of L245 Steel and Ni-W Alloy Coating in Alkaline Sodium Sulfide Solution

天然气、石油的开采和运输过程中,析出水中的硫含量越来越高,硫的大量沉积导致集输管道连接件的严重腐蚀。为了提高基体钢的耐蚀性,延长连接件的使用寿命,在管道连接件上电镀一层Ni-W镀层,以提高连接件的耐蚀性能。通过浸泡法和电化学方法研究了Ni-W镀层及L245钢在含Na2S模拟采出水环境中的腐蚀行为,采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)分析了Ni-W镀层与L245钢腐蚀产物的表面形貌、成分和结构,并对比分析了Ni-W镀层的耐蚀性。结果表明:硫离子会加速基体L245钢的腐蚀,Ni-W合金镀层可以有效提高L245钢在含硫溶液中的耐蚀性能;硫离子浓度为0.005 0 mol/L时,硫离子水解反应生成的OH-吸附在钝化膜表面,减缓了Ni-W镀层表面的腐蚀。

During the exploitation and transportation of natural gas and petroleum,the sulfur content in the precipitated water is getting higher and higher,which could cause severe corrosion of the carbon steel joints in the gathering pipeline. In order to improve the corrosion resistance of steel substrate and extend the service life of connector,a Ni-W coating was prepared on the carbon steel connecting piece by electroplating method for improving the corrosion resistance of the carbon steel connecting piece. The corrosion behavior of Ni-W coating and L245 steel in the environment containing Na2S simulated production water was studied by immersion method and electrochemical method. Furthermore,the surface morphology,composition and structure of the corrosion products of Ni-W coating and L245 steel were compared and analyzed by scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Results showed that the sulfur ions could accelerate the corrosion of L245 steel,and the Ni-W alloy coating would effectively improve the corrosion resistance of L245 steel in a sulfur-containing solution. When the sulfur ion concentration was 0.005 0 mol/L,the OH-generated from the sulfur ion hydrolysis reaction was adsorbed on the surface of the passivation film,which reduced the corrosion of the Ni-W coating.