Corrosion Behaviour of lead in salt solutions: I. Uncoupled lead electrodes

Abstract

The corrosion behaviour of Pb in NaCl, Na2SO4, sea water and tap water and in cement extracts has been studied by means of weight-loss and potentiostatic methods. It has been found that the dependence of the corrosion rate on the Cl− or SO2−4 ion concentration conforms with a relation of the type, log W = a—b log C, where W is the corrosion rate, C the salt concentration and a and b are constants. Both anions were shown to behave as anodic inhibitors. A trial is made to interpret the results by means of an adsorption model based on the simple Langmuir isotherm. The potentiostatic technique helped to. throw light on the nature of the films formed on the electrode surface in the different media. Primary passivity is caused by the formation of sulphate and/or chloride films. Secondary passivity sets in when the salt film and any lower oxide films are oxidised to PbO2. The corrosion rates in sea water and in cement extracts are diminished by Cl− and SO2−4 ions.