DEVELOPMENT OF SILICON-CARBON BASED HIGH CONDUCTING CARBON ANODE FOR CATHODIC PROTECTION

Abstract

Corrosion cost is always a challenge in any industry and such cost can be reduced by effective protection. Cathodic protection is the most prominent method used to protect pipelines and offshore platform. This is carried out using sacrificial anode or impressed current system. Silicon-Carbon anode was developed as a potential substitute to existing magnesium and zinc anodes. Natural coal and ferrosilicon were pulverised and sieved to obtain 50 μm and 75 μm particle sizes. The varied weight percent of coal and ferrosilicon was added to constant weight percent of grey cast iron. The anodes were produced by the sand casting method. The hardness of the anodes and the effects of particle sizes were evaluated. Tafel plot from electrochemical method was adopted for the study of the corrosion behaviour of the anodes and mild steel. Optical, scanning electron microscopy and X-ray diffraction analysis were utilised for microstructural analysis and phase characterization respectively. It was observed that 50 μm particle size improved the hardness and corrosion resistance property of the anode better than 75 μm. Carbon addition increased the corrosion resistance of grey cast iron. All the anodes produced had lower electrode potential than the mild steel. The mild steel has a corrosion potential of -540.907 mV Ag/AgCl while the anode with 30 wt% coal, 50 μm particle size exhibits the lower potential value of -588.533 mV Ag/AgCl and the least potential value of -648.382 mV Ag/AgCl display by the anode with 5 wt% coal and 25 wt% ferrosilicon at 50 μm particle size. The potential of the anodes shows that they are capable of protecting the mild steel. The silicon-carbon anode with 5 wt% coal and 25 wt% ferrosilicon at 50 μm particle size is the most suitable anode to cathodically protect the mild steel immersed in the marine environment