THE INFLUENCE OF WATER CONCENTRATION ON THE CORROSION OF LOW ALLOY STEELS IN THE SYSTEM METHANOL – ETHYLENE GLYCOL – ACETIC ACID

Abstract

The behaviour of three types of steel with a variable carbon content (from 0.2 to 0.4%) is studied in medium of methanol - 10% ethylene glycol - 5% acetic acid with water concentration between 1% to 5%. The weight losses are measured; also the polarisation anodic curves are plotted, and the corrosion parameters are established. IR spectroscopy, X-ray diffraction and chemical analysis are the methods used for analysing the corrosion compounds. With the obtained data, a corrosion mechanism is assigned. An optimum ratio between water and acid is established in order to obtain the passive oxyhydroxylic layer.