Protection of Copper by Pretreatment with Benzotriazole

Abstract

Corrosion protection afforded by pretreating copper in aqueous benzotriazole solutions at temperatures ranging from 25 to 100 C were evaluated. Electrochemical characteristics of pretreated copper mirrors were monitored using rapid polarization techniques. Thickness of surface films were analyzed by infrared multiple reflectance spectroscopy. Topography of surface films prior to and subsequent to test exposures was examined by scanning electron microscopy. Defects in protective films on pretreated copper mirrors were detected by immersion in silver nitrate solutions. The resulting silver “decorations” identified both the location and density of active corrosion sites in the multilayer protective films. Exchange current densities, corrosion current densities, corrosion rates determined by chemical analyses, electrical double layer capacities, and the densities of active corrosion sites all showed similar dependencies on pretreatment temperatures. All techniques indicated that the protectiveness of CuBTA films (of equal average thickness) formed on copper, increased with increasing pretreatment temperatures up to 100 C.