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Physicochemical aspects of metal corrosion inhibition in aqueous solutions

“…In the former case, complexones often accelerate corrosion; if it occurs at potentials of the active metal dissolution range, carboxyl-containing complexones are most dangerous, whereas phosphonic acids are most dangerous for oxidised metal as they can cause the formation of small pits. 14,81 If the value of E cor is outside the potential range where metal ionisation with formation of a soluble complex is thermodynamically possible, adsorption of a suitable ligand can block the corroding surface (at least partially), change the c 1 potential of the electrode, etc. Furthermore, many phosphonic complexones form barely soluble polynuclear complexes at high metal/ligand activity ratios m = [M n+ ] : L Since m should be high in the near-electrode layer at low complexone concentrations and active metal dissolution, it is such complexonates that can be formed on the surface.…”

Barium Sulfate Crystallization in the Presence of Variable Chain Length Aminomethylenetetraphosphonates and Cations (Na+ or Zn2+)

“…Phosphonates, when blended with certain metal cations and polymers, reduce the optimal inhibitor concentration needed for inhibition due to synergistic effects. 14,15 Synergism is one of the important effects in the inhibition process and serves as the basis for the development of all modern corrosion inhibitor formulations.…”

Structural Mapping of Hybrid Metal Phosphonate Corrosion Inhibiting Thin Films

“…[9] The protective properties of aminophosphonic acids and their magnesium and calcium complexes were studied in soft water. 1,1-hydroxycarboxypropane-3-amino-di(methylenephosphonic) and hexamethylenediamine-N,N-tetra(methylene-phosphonic) acids could suppress the corrosion of steel in water completely.…”