Using a Doe and Eis to Evaluate the Synergistic Effects of Low Toxicity Inhibitors for Mild Steel

Abstract

-Inhibitors are widely used to prevent corrosion in cooling-water systems, and their protective performance can be enhanced by combination. The aim of this paper is to identify possible synergistic effects between four low toxicity substances used as corrosion inhibitors for mild steel in industrial cooling-water systems. Electrochemical measurements were obtained following a design of experiments (DOE) where the independent variables were the inhibitors concentrations and the response variable the charge transfer resistance estimated from impedance diagrams. Potentiodynamic polarization curves show that all of them act as anodic corrosion inhibitors. Among the tested formulations, only the interaction between sodium molybdate and sodium tungstate showed statistically significant effects, indicating that they can perform better when used together. The results of this work show the importance of using a statistical tool when designing inhibitor mixtures.

Inhibition of Bicarbonate-Chloride Corrosion and Passivation of Carbon Steel under Open-Circuit Conditions by Molybdate

“…40 However, it has not been widely used in corrosion research with only a few groups using this technique and its variants such as Response Surface Methodology. [41][42][43] DOE is useful in screening out input parameters that have insignificant effects and also determining whether there are interaction effects between the input parameters, e.g. whether the presence of factor X 1 affects the effect of factor X 2 on the output Y.…”