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Modified hydrotalcites for improved corrosion protection of reinforcing steel in concrete – preparation, characterization, and assessment in alkaline chloride solution
Author(s) -
Yang Z.,
Fischer H.,
Cerezo J.,
Mol J. M. C.,
Polder R.
Publication year - 2016
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201508618
Subject(s) - hydrotalcite , corrosion , chloride , ion exchange , chemistry , sodium , nuclear chemistry , inorganic chemistry , sodium nitrite , sodium carbonate , ion , catalysis , organic chemistry
Six MgAl hydrotalcites (Mg/Al = 2 and 3) were synthesized through the modification of two carbonate hydrotalcites (i.e., Mg(2)AlCO 3 and Mg(3)AlCO 3 ) by two amino acids (11aminoundecanoic acid and paminobenzoic acid) and sodium nitrite. They were characterized by means of XRD, FTIR, TG/DSC, and elemental analysis. The ion exchange of the modified hydrotalcites (MHTs) were investigated in alkaline chloride solution and the results showed that ion exchange occurred between free chloride ions and the intercalated inhibitive anions in MHT. The corrosion inhibition of three MHTs (Mg/Al = 2) was evaluated based on the open circuit potential and linear polarization resistance evolution of steel coupons in 0.1 M NaOH solution stepwise enriched with chlorides and the results showed that MHT, in particular, Mg(2)AlpAB exhibited an improved corrosion inhibiting effect in terms of a higher chloride threshold compared to its constituent free inhibitor ions (i.e., pAB). This study confirms the dual protection that MHT, in particular, Mg(2)AlpAB, offers to the steel: capturing chlorides and simultaneously releasing the intercalated inhibitors to further protect the steel from corrosion.