Alkyd coating containing metal phosphomolybdate/cobalt ferrite nanocomposites as efficient corrosion inhibitor for stainless steel 316L in saline solution

Nanocomposites of some metallo-phosphomolybdates (ZrO, VO, Mn and Mg-POMs) with cobalt and manganese ferrites (CoFe2O4 or MnFe2O4) were synthesized and evaluated as efficient and inexpensive green anti-corrosion coatings for commercial stainless – steel (SS) in a 3.5% NaCl medium. The synthesised composites were characterized using electron microscopic (SEM and TEM), spectroscopic (XRD, EDX and AFM) techniques and contact angle measurements. The resultes confirmed the incorporation of both the M-POMs and the ferrite nanoparticles (NPs) in the composite matrices. Paint formulations based on the new M-POM/ferrite nanocomposites and containing alkyd resins were prepared and applied to Stainless-Steel substrates. Electrochemical techniques such as EIS (Nyquist, Bode) and Tafel were used to investigate the anticorrosive properties of the prepared coating materials. The measurements revealed that the POM/Ferrite composite coatings onto SS exhibited enhanced anticorrosive properties compared to those of both the separate ferrite or POM. The value of Rp of the ZrO- and Mn-POM coatings compared to its POM/cobalt ferrite composites as obtained from Tafel measurements increased from 1395 kΩ cm2 to 6770 kΩ cm2 and 112.8 kΩ cm2 to 692 kΩ cm2 respectively indicating high corrosion protection of the coated steel panels.