Electrochemistry and Engineering Study of Molecular Protective-Films to Steel-Alloys

The syntheses and characterisation of Rare-Earth-Metals (REMs) complexes, via the use of green organic esters such as Pyridinecarboxylate (Pyc) and hydroxylnaphthoate (Hnp) to form stable compounds ie. Lanthanide-hydroxylnaphthanote (Ln-Hnp), has been demonstrated to be the most preferred compounds to form a good protective-film over steel-alloys. The electrochemical techniques of Linear Polarisation Resistance (LPR) and Cyclic-Potentiodynamic Polarisation (CPP) used in the studies demonstrated strong protective properties to the steel-alloys from the E corr-potential and I corr-current. This is because the I corr-current was reduced by many folds when coupons were immersed in NaCl (0.01M) as a control bulk-electrolyte. The data has also confirmed that the Ln-Hnp complexes clearly displayed a mixed-type of protective function. Thus, the overall metal dissolution rate of steel alloys is mitigated and the data also indicated that it has shown a healing mechanistic process building a dense molecular composite-films up to 5-micron thick when alloy-coupons were immersed into the solution containing REMs complexes. The characterisation of in-situ treated surfaces by the use of ATR-FTIR, FTIR-mapping-microscopy and Raman spectrum revealed its overall protective characteristic which were discussed in this paper