"bronze Disease" Mechanism And Prevention Study

Potentiodynamic polarization method was used to study the influence of Cl", HCO3- and SO42- on the corrosion of bronze. It was found that Cl-. and SO42- are active anions and HCO3- is a weak inhibitor to bronze. But when Cl" and HCO3- are coexistence, SO42- can expand the passivation of the system.Simulated occluded corrosion cell(OCC) and Electrochemical measurements (potentiodynamic polarization curves, AC impedance) were used to study the changes within the OCC of bronze, in solution of 0.01M NaCl + 0.01M NaHCO3 +0.01M Na2SO4 and the influence of MoO42- on the OCC at 30C.It was found that, when there was no added MoO42- in the bulk solution, as anodic current passing the cell, the pH value dropped quickly at beginning while slowly after it reached about 6. Meanwhile the Cl- and SO42- migrated into the OCC and the corrosion rate increased significantly because of the change of the corrosion mechanism.When MoO42- added into the bulk solution, it migrated into the OCC. MoO42- can compete with Cl" on migration and reaction with Cl" on the surface of bronze so as todecrease the Cl- concentration. It also can slower the pH fall in the OCC. So MoO42-can retarded the expansion of the local corrosion of bronze.Complex inhibitor method was used to study the preservation of bronze disease. It was found that MoO42- and BTA can cooperation to retarded the induction of the local corrosion of bronze.