Nanostructured silane coatings for corrosion protection of low carbon steel

摘要

The overall aim of this work is to design an alternative metal pre-treatment with improved corrosion resistance and low environmental impact. Hybrid silane pre-treatments with nano-additives and corrosion inhibitors as fillers for corrosion protection of low carbon steels using sol-gel processing technique were developed. Multifunctional silane molecules used to design the hybrid silane films were based on cross-condensation between an epoxy-silane, 3-glycidoxy-propyl-trimethoxy-silane (GPTMS) and methyl-triethoxy-silane (MTES) in acid catalysis condition. The current scope of work involves different concentrations of cerium triflates as corrosion inhibitor at 250, 500, 750 and 1000 ppm. The corrosion resistance of the modified silane films cerium triflate and silica nanoparticles was evaluated by electrochemical measurements using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The corrosion studies were complimented by investigation of surface topography using scanning electron microscopy coupled with EDX (SEM-EDX). In this work, optimum concentration of the cerium activated systems for the best corrosion resistance of low carbon steel was established at 1000 ppm. It is proposed that the cerium triflates within the silane films, forms cerium oxides or hydroxides on cathodic and anodic regions as a result of increase in pH during corrosion, thus hindering corrosion onset.