Studies in the Corrosion and Inhibition of Mild Steel in Sodium Fluoride Solutions by Small Amplitude Cyclic Voltammetry

Abstract

Corrosion of ASTM 212 steel in sodium fluoride solutions has been studied by small amplitude cyclic voltammetry (SACV) and by direct weight loss measurements. The results from these two methods are comparable. Corrosion rates vary between 19·5 and 33·3 mg.dm⁻²d⁻¹ (mdd) in sodium fluoride concentrations between zero and 2% in systems open to the atmosphere. In nitrogen saturated sodium fluoride solutions the corrosion rates were found to be very low (∼5 mdd). Corrosion inhibition by sodium chromate was also examined. Inhibitive efficiencies derived from 1/R_P measurements and from direct weight loss are comparable. About 90% inhibition was achieved with 800 ppm of sodium chromate in 0·5% sodium fluoride.