Inhibition effect of some commercial corrosion inhibitors on mild steel in 7.0 M phosphoric acid

Corrosion tests were carried out in order to find the best inhibitor for the protection of steel pipelines used in [H.sub.3]P[O.sub.4] and fertilizers industry. The corrosion inhibition efficiency of five commercial inhibitors was investigated on mild steel by using electrochemical methods (EIS and polarization curves) in a 7M [H.sub.3]P[O.sub.4] solution (pH 0.5). The efficiency of best corrosion inhibitors was tested at different concentrations. Key words: mild steel, corrosion inhibitors, electrochemical impedance spectroscopy, polarization curves, inhibitor efficiency, phosphoric acid.