EFFECT OF CHROMIUM CONCENTRATION IN BIOCORROSION PROCESS

摘要

Microorganisms strongly participate on the corrosion processes without changing the electrochemical phenomenon nature. This work had the aim to check out the effect of chromium concentration, as a carbon steel alloy component, both on biofilm formation and on corrosion rates. Three carbon steel alloys, 0,03, 1 and 15% chromium, had been studied. A circulation looping system made of PVC tubes was used. Metal probes and electrodes, for electrochemical monitoring, were fixed to this system. After 15 days, the microorganisms present in the biofilm were quantified and the corrosion rates were evaluated. The results had shown a greater microorganism concentration on alloys with 0,03% chromium. The increase of the amount of chromium in metals alloys led to smaller microorganisms concentration on biofilms, and consequently on the corrosion rates. Analysis of the corrosion rate and galvanic current by electrochemical monitoring had shown that the higher chromium concentration caused a smaller corrosion rate.