Indian Journal of Science and Technology

Abstract

Background/Objectives: Zeolite is emerging as an environmental-friendly alternative to hard chrome, cadmium and epoxy polymers based corrosion resistance coating for steel, magnesium and aluminium alloys. Owing to inert nature, low modulus of elasticity and high strength, zeolite coatings are being used as anti-corrosive coatings for metallic substrates. Methods: Molten Salt Method was used to convert fly ash to zeolite. The synthesized zeolite was characterized using X-Ray Diffraction (XRD) technique and Scanning Electron Microscopy (SEM). The synthesized zeolite was coated on mild steel samples using polymer binder (Polyvinylidene fluoride-PVDF). Zeolite-coated mild steel samples and uncoated samples were exposed to sea water for 2 months. The corrosion behaviour was found using Weight-loss method and Electrochemical Method (Potentiodynamic Polarization Method-Tafel Plot analysis). Corrosion studies of samples were also carried out in different acid solutions (Sulphuric Acid, Nitric Acid, Hydrochloric Acid) for a month. Corrosion rates of samples and inhibition efficiencies of coaed-samples were found using Weight-loss Method. Findings: Results showed that fly ash was converted into zeolite with Sodalite and Cancrinite as major crystalline phases. The optimum zeolite to binder ratio was found to be 1:0.3. The zeolite-coated samples had excellent corrosion inhibition efficiency in sea water (above 85%). They had corrosion inhibition efficiencies above 80% in acid solutions. Application: This study presents experimental results dealing with the possibility of transforming fly ash into a zeolite material and using the synthesized material as an effective anti-corrosive agent.

Keywords:  Fly Ash, Zeolite, Weight-Loss Method, Tafel Plot, Corrosion Rate, Inhibition Efficiency