Effect of South China Sea Water on Corrosion Behaviour of Copper Alloy and Mild Steel

The oxidation behaviour of copper alloy and mild steel were investigated in South China Seawater at temperatures around 50° C for a period of 10 h. A procedure was applied to measure the pH of the seawater at elevated temperature. The susceptibility to heavy internal oxidation increases with increa sing time. A mechanism involving chloride and oxygen dissolution in the alloy matrix as well as internal oxidation, exhibits mass gains throughout the experiment. Immersed in South China Seawater, the alloy of incomplete recrytallisation showed thick, loose and porous films, of which the inner layer was metallic oxides/chlorides and the outer layer contained a great amount of seawater species, and of which the underlying substrate was found with severe inter-granular corrosion. Overall, the South China Seawater species have a deleterious effect on the surface of the alloy and rapid degradation is noted. The scale morphologies were determined by Optical and Scanning Electron Microscopic techniques.