A corrosion-protective film formed on a carbon steel by an organic phosphonate
1997; Elsevier BV; Volume: 39; Issue: 10-11 Linguagem: Inglês
10.1016/s0010-938x(97)00086-3
ISSN1879-0496
AutoresX.H. To, Nadine Pébère, N. Pelaprat, B. Boutevin, Yves Hervaud,
Tópico(s)Corrosion Behavior and Inhibition
ResumoSurface treatments have been carried out on a carbon steel in solutions containing different phosphonates. The compounds were dissolved in an ethanol/water mixture (80%20%). Corrosion protection afforded by laurylphosphonic acid (LPA), ethyllaurylphosphonate (ELP; also called lauryl phosphonic acid monoethylester) and diethyllaurylphosphonate (DELP) has been studied by steady-state current-voltage curves and electrochemical impedance measurements with a rotating disc electrode. Corrosion protection was only obtained for the ethyllaurylphosphonate (ELP), which is able to form a relatively thick film on the carbon steel surface. Thus, analysis of the variations of electrolyte resistance through the pores and defects of the film against concentration and immersion time in the solution containing the monomer allowed us to find the optimum parameters for treatment giving the best protection (24 h of immersion and 5% ELP concentration). Electronprobe microanalysis corroborates that the film is thick and porous. Infra-red spectroscopy indicates that the film was formed by reaction of the organic phosphonate with the steel surface to produce a metal salt.
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