Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Electrical Engineering, Measurement and Control Technology
Abstract The electrochemical behaviour of graphite-epoxy composite materials (GECM) in neutral 3.5% aqueous solutions of NaCl has been investigated. Two types of composite and pure graphite have been studied. The composite material shows a high value of electrode potential ranging between −40 and +70 mV versus SCE, and behaves as cathode when coupled to alloys. The effects of chloride ion concentration, pH, temperature, nature of cations and anions, and resistance of the epoxy matrix to environmental agents on the rate of oxygen reduction reaction on GECM electrodes are reported. Moreover, polarization studies performed on GECM-aluminium alloy couples show that polarization occurs mainly at the composite interface. From potentiostatic anodic polarization curves of different alloys and cathodic polarization curves of GECM, the initial galvanic corrosion current densities for most alloy-GECM couples of interest in the aerospace industries have been obtained. These values are strongly affected by environment durability of the epoxy matrix and variation by one or two orders of magnitude are observed. Despite the latter discrepancy, these data can be helpful in the assesment of a galvanic series based on galvanic current density for alloy-GECM joints.
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