INHIBITING ACTION OF ALPHA-PYROPHTHALONE IN COPPER CORROSION

The mechanism of the inhibiting action of alpha-(pyridyl)-1,3-indandio ne (known as alpha-pyrophthalone, alphaPP) in the corrosion of copper in nearly neutral solutions is studied by XPS analysis of the metal su rface, capacitance and polarization measurements. Alpha-Pyrophthalone decreases the rate of the cathodic as well as of the anodic partial re action. The capacitance measurements show that the inhibitor's molecul es adsorb on the copper surface at potential values more negative than that of the corrosion potential. According to the data of the XPS ana lysis the inhibiting action of alpha-pyrophthalone on the corrosion pr ocess is determined by the formation of a Cu(alphaPP)2-Complex on the copper surface. The composition and the structure of the inhibiting fi lm show a complex process of the formation and the precipitation of th e Cu(alphaPP)2-complex on the surface.