Abstract
Potentiodynamic measurements of anodic and cathodic polarization curves of copper, nickel, aluminium, brass (30%Zn), cupronickel (30%Ni) and aluminium brass (2%Al) were carried out in stagnant and moving 3%NaCl aqueous solutions containing hydrogen sulfide of 10 ppm. Anodic and cathodic reactions of these copper alloys in 3%NaCl aqueous solutions were both strongly accelerated by the coexistence of hydrogen sulfide and dissolved oxygen. Anodic films on copper alloys easily broke away in moving solutions. The surface films formed on these metals and alloys in a 3%NaCl solution were found, by electron diffraction method, to be mainly composed of Cu2O, and in the case of the 3%NaCl aqueous solution containing hydrogen sulfide, to be a certain substance of unknown structure. This substance is considered to be a kind of sulfide. The resistance of copper alloys against corrosion of the type of cathodic control in the 3%NaCl aqueous solution containing hydrogen sulfide can be put in the following order judging from the electrochemical polarization characteristics; cupronickel>aluminium brass\gtrsimbrass>copper in anodic controlled corrosion and aluminium brass\gtrsimbrass>copper>cupronickel.
