Galvanostatic polarizations of some Sn-Cd alloys in some carboxylic acids

The anodic and cathodic polarization of three Sn-Cd alloys in solutions of acetic, succinic and malic acids was investigated. Corrosion potentials of the three alloys did not vary appreciably with the concentration of the acid or its nature. Anodic polarization of the 65% Sn-Cd alloy revealed one arrest before the potential of O2 evolution and corresponds to the SnO/SnO2 system. Two arrests were manifested by the anodic curves in the case of the 50 and 35% Sn-Cd alloys; these correspond to the Cd/Cd++ and SnO/SnO2 systems respectively. Cathodic Tafel slopes (b-) for the h.e.r. on the three alloys range from −130 up to 202mV. Values of the exchange current densities (i0) range from 1.1×10^−7 up to 1.4×10^−10 A cm−2.