LAUSR

Abstract Implementation of Schiff base metal complex/SiO 2 nanocomposite as a multifunctional modifier in steel epoxy coating represents a novel engineering issue for surface treatment technology. The present work investigates the application of epoxy coating modified with several metal (Co(II), Zr(IV), Ni(II), Cu(II) and Cr(III)) complexes of Schiff base versatile ligand namely p-Phenylamine-N(4-chloro salicylaldenemine) (HL), composited with SiO 2 nanoparticles to enhance its protective behavior and mechanical resistance on the C-steel surface. Characterizations of silica nanoparticles were demonstrated by using transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive of X-rays (EDX) and X-ray diffraction analysis for integral clarification. FT-IR discriminatory spectra for polyamine cured blank unmodified conventional epoxy and surface modified HL and its metal complexes epoxy/SiO 2 hybrid nanocomposite cured coatings were checked. The protective behavior of the investigated modified epoxy nanocomposite coatings against unmodified blank conventional epoxy on the steel surface was clarified by studying the surface morphology of the cured coated films after the immediate exposition to corrosive salt spray cabinet for 500 h and employing 5% NaCl aggressive solution. Modified cured Cr(III) and Ni(II) complex epoxy/SiO 2 nanocomposite coated films (NS/MCE-F3 and NS/MCE-F5) manifested the minimum corrosion rate (CR) at 0.00063 mm/y and a superb protection efficiency (PE) recorded at 99.80%. The mechanical resistance properties of the nanocomposite coatings were examined by adhesion cross-cut, bend, impact, and abrasion (film stiffness) coating tests to underline their enforcement efficiency. NS/MCE-F3 and NS/MCE-F5 coated films boosted an outstanding mechanical resistance behavior on the C-steel surface in contrast with complete deterioration for blank conventional epoxy. The main reason for the superior anti-corrosion and mechanical performance properties observed in case of the nanocomposite coatings modified with Cr(III) and Ni(II) complexes may be attributed to the higher magnetic dipole moment of these complexes than the others in which enhances their electronegativity, cross-linking density and chemical bonding with the steel surface via the donor-acceptor interactions.