Entartrage du fer dans l’eau de la nappe phréatique d’Alsace

Etude par mesures d’impédance électrochimique

Application of electrochemical impedance measurements to studies of calcareous scaled iron in Alsace groundwater

Laboratoire de métallurgie et chimie des matériaux, Ecole Nationale Supérieure des Arts et Industries de Strasbourg

Abstract

Within a general study of interactions between calcareous deposition and corrosion of natural water circulating pipes, this paper report on the possible protecting rôle against corrosion of the layer of calcium carbonate.

Electrochemical impedance measurements of metal-scale-water interface at -IV/SCE permit us to evaluate the coating performance of calcareous deposits. A proposed equivalent circuit is used to analyse the impedance data obtained during the calcareous deposition. The role of dissolved oxygen is examined.

The corrosion behaviour of scaled surfaces is determinated by open circuit potential measurements, electrochemical polarisation studies and scanning electron microscopy (SEM) examination. This later corrosion experiments reveal an important localised corrosion in the form of pits which grow on scale defaults.