Contribution to comprehensive study of aluminium alloy Aa 5083 corrosion induced by elemental mercury in LNG industries

Abstract

Corrosion induced by elemental mercury in aqueous media of industrial Aluminium alloys AA5083 used in heat exchanger industries of natural gas liquefaction has been studied by linear sweep voltammetry on rotating amalgamated disk electrode. Corrosion process depends on: • Chemical processes of amalgamation of aluminium with mercury. • Diffusion process of aluminium in amalgam. • Electrochemical oxidation of aluminium on amalgamated Interface/water. The diffusion step appears different from that usually found in studies of aqueous corrosion and was not dependent on rotation of electrode but on diffusion of dissolved aluminium in the amalgam before the electrochemical oxidation of amalgamated metal. This is the limiting step of the process at stationary phase of the chemical amalgamation. This occurs at contact time mercury-aluminium longer than 36 min .For shorter times less than 30 min, chemical amalgamation controlled the process. Characteristic parameters of electrochemical behaviour of amalgamated electrodes were investigated: time of cathodic deposit of mercury, time of immersion of electrode in electrolyte before polarisation as well as potential scanning rate. Nigerian Journal of Chemical Research Vol. 10, 2005: 39-48