Study on corrosion inhibition by N-sulfonic amino-dimethylenephosphonic acid

The corrosion inhibition by SADP(N-sulfonic amino-dimethylene phosphonic acid) on 0Crl3 stainless steel was studied by linear polarization and anodic polarization curve methods in 0.10mol/L H₂SO₄ solutions, compared with HEDP (1-hydroxyethylidene-1, 1-diphosphonic acid) and ATMP (aminotrimethylenephosphonic acid). It was found that these three phosphonic acids have remarkable inhibition effect on the corrosion of 0Cr3 stainless steel in H₂SO₄solutions. The corrosion inhibition mechanism by SADP HEDP ATMP on 0Crl3 was found to be die geometric blocking effect. Results showed that the adsorption of all these three phosphonic acids follows the Langmuir adsorption isotherm. The order in the corrosion inhibition efficiency may be arranged as follows : η_SADP > η_ATMP > η_HEDH.