Corrosion Behavior of the Amorphous Ni - W Coating in Sulfur - Containing NaCl Solution

Abstract

During the development of oilfield, the produced water with high salinity is seriously corroded to pipeline equipment. Owing to the good corrosion resistance, amorphous Ni - W coating applied on the surface of the pipeline connector can improve the anti - corrosion performance of connector. In this work, the corrosion behaviors of amorphous Ni - W coating and L245 steel in sulfur - containing NaCl solution were studied through immersion and electrochemical methods. Additionally, the surface morphology, composition, and structure of Ni - W coating and L245 steel were analyzed by scanning electron microscope (SEM), energy spectrum (EDS) and X - ray diffractometer (XRD), and the corrosion principles of amorphous Ni - W coating and L245 steel were studied through electrochemical tests. Results showed that sulfide ions would accelerate the corrosion of the L245 steel, and the amorphous Ni - W coating could effectively improve the corrosion resistance of L245 steel in the sulfur - containing NaCl solution. When the sulfide ion concentration was 0.001 0 mol/L, a passivation film formed on the surface of amorphous Ni - W coating, which slowed down the corrosion. When the sulfide ion concentration was 0.005 0 mol/L, Cl- and S2- could work together, resulting in a pitting corrosion on the surface of the amorphous Ni - W coating.

Keywords

• amorphous ni - w coating|passivation film|sulfur ion|nacl solution|corrosion|electrochemical test