Formation of ultrathin protective coatings on low-carbon steel from borate buffer-dodecylphosphonic acid solution

Passivation of mild steel by sodium octylphosphonate in neutral aqueous solution

“…As regards metal passivation, phosphonic acids are the most interesting objects that, similarly to carboxylates, contain hydrophobic components in the molecule and can form self-assembled layers on surfaces [17][18][19][20][21][22]. In addition to the passivating effect, treatment of a metal by phosphonic acids can impart hydrophobic properties to the surface [21] that can also play an important role in corrosion protection.…”

“…Additional information about the formation of self-assembled layers of alkylphosphonates and the mechanism of mild steel passivation by these compounds was obtained in [17][18][19]22].…”

Organic corrosion inhibitors: where are we now? A review. Part IV. Passivation and the role of mono- and diphosphonates

“…This fact allowed the authors to assume that APhC 12 is able to protect St3 by the "nonoxide passivation" mechanism in a manner similar to that previously proved for the anions of certain higher carboxylic acids [4,14]. Chronopotentiograms of St3 steel in deaerated borate buffer solution with pH 7.3 at cathodic polarization, i = 10 μA/cm 2 , after passivation of the electrode: 1 -by anodic polarization in borate buffer to E = 0.2 V; 2 -same, but with an exposure time of 10 min at E = 0.2 V; 3 -by anodic polarization, but with preliminary cathodic activation in the presence of 5 mM APhC 12 rather that in the pure buffer [19].…”

“…They concluded that "the oxide plays an important role in the stability of the protective layer, but the bare surface of iron is disadvantageous for phosphonate binding." However, introduction of APhC 12 in a borate buffer solution with pH 7.3 revealed some important features of its effect on the passivation of mild steel (St3) [19]. APhC 12 was introduced into the studied solution containing no corrosive anions in the form of a dispersion in the same buffer, or at C = 5 mmol/l it was dispersed directly in it.…”

“…These studies can be divided into two groups. The first of these includes works in which the protective properties of APhs with a relatively small alkyl length, C 7 -C 10 , were studied, which made it possible to obtain their thin layers, including SAMs, in aqueous solutions [16][17][18][19][20][21][22][23][24][25][26]. In the second group more hydrophobic monophosphonic compounds were studied, mainly octadecylphosphonic acid (APhC 18 ), that cannot be applied from aqueous solutions [27][28][29][30][31][32][33].…”