Characteristics of corrosion product films of copper alloy in South China Seawater

Abstract

The corrosion behaviour of Copper-base alloy was investigated in three different states south china seawater at 50 & 70 0 C for the period of 10 h in atmospheric condition. A procedure was applied to measure the pH of the seawater at elevated temperature. The sucesceptibility to suffer a deep attack by internal oxidation increases with increasing temperature and time. A mechanism involving chloride & 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. Over all, the south china seawater species have 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.