Corrosion-resistant mulberry fruit (Morus nigra L.) extracts incorporated hybrid (GPTMS-TEOS) composite silanol coatings for low carbon steel protection

The present work aimed at the evaluation of mulberry (Morus nigra L.) fruit extracts-doped hybrid sol-gel coatings' corrosion resistance performance for low carbon steel in NaC1 electrolyte. Alkoxysilane formulation was prepared to utilize 3-glycidoxypropyltrimethoxysilane and tetraethyl orthosilicate precursors. The corrosion inhibitive properties of extracts-doped composite coatings on low carbon steel surface in NaC1 electrolyte were determined by exploiting electrochemical impedance spectroscopy, electrochemical noise measurement and potentiodynamic polarization. The corrosion inhibition efficiencies obtained were 85.57% and 81.37% for hybrid coatings doped with mulberry ethanol extract and water extract, respectively. It was noted that the hybrid silanol film applied low carbon steel which was doped with 750 ppm mulberry ethanol extract rendered higher corrosion resistance. Additionally, the Tafel slopes indicated that mulberry extracts function as "mixed type" corrosion inhibitors, particularly prevailing cathodic inhibition. Surface characteristics of coated low carbon steel plates were researched engaging scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and wettability measurement. Fourier transform infrared spectroscopy established Fe-O-Si bonding among mild steel substrate and composite coating. Scanning electron micrographs affirmed that the coating provided better corrosion mitigation due to the inhibitive efficacy of the doping. Wettability analysis revealed that low carbon steel treated with 750 ppm mulberry ethanol extract doped coating was highly hydrophobic. [GRAPHICS] .