SEM-EDS characterization of natural products on corrosion inhibition of Al-Mg-Si alloy

Abstract

The corrosion resistance of aluminum and its alloys is the subject of tremendous technological importance due to their increased industrial applications. The corrosion protections and the mechanism of corrosion inhibitions of natural products for an Al-Mg-Si alloy in seawater were investigated at room temperature. The surface morphology was studied by means of macro scale electrochemical techniques and localized microscopic methods, i.e., Scanning electron microscope (SEM) with associated elemental analysis by energy dispersive spectrometer (EDS). SEM examinations provided morphological characterization of the surface of Al-Mg-Si alloy sample before and after immersion in seawater; meanwhile surface analytical techniques by the EDS allowed us to investigate detail the chemical composition of aluminum oxide layers. The experiments were performed with Al-Mg-Si alloy, immersed in a 5 L beaker containing seawater with and without the natural products for 60 days at room temperature. The SEM results indicate that the natural products (natural honey, vanillin, and tapioca starch) absolutely inhibited the corrosion products on the specimen surfaces. They also protected the passive film from dissolution in seawater. The EDS spectrums were determined that carbonaceous, carbonyl, methoxy and hydroxyl groups as functional groups of natural products in inhibition mechanism.