PASSIVATION AND PITTING CORROSION OF ALPHA-BRASS (CU/ZN - 63/37) IN NEUTRAL BUFFER SOLUTIONS CONTAINING CHLORIDE-IONS

The passivation behaviour and pitting corrosion of a commercial grade alpha-brass (Cu/Zn: 63/37) in neutral buffer solutions (borate and phosphate) in the presence and absence of chloride ions were investigated by electrochemical techniques. The results indicated the dezincification in absence of chloride ions at highly enough anodic potentials and both dezincification and pitting corrosion in the presence of chloride ions. The pitting susceptibility was found to depend on the composition of the buffer solution, chloride ion concentration and nature of the passive layer on the metal surface before pitting. Current transients corresponding to passivity, dezincification and pitting corrosion were identified and analyzed.