Effect of Paramagnetism on the Corrosion Abatement of Mild Steel

ABSTRACT

The corrosion rates of magnetized mild steel coupons in HCl solutions were studied using the weight loss method. The coupons were magnetized with a laboratory electromagnet at 0.38T, 0.57T, 0.76T, 0.95T and 1.51T and immersed in HCl solutions of pH ranging from 2 to 6. Experimental results showed that coupons magnetized at 0.76T, 0.57T and 0.38T exhibited higher corrosion rates than their non-magnetized counterparts at pH values less than 5. At pH 5 and above however, they showed lower corrosion rates than the non- magnetized coupons. Coupons magnetized at 0.95T and 1.51T however, reduced the corrosion rate below those of the non-magnetized coupons for the entire pH range from 2 to 6 studied. Inhibition efficiency reached 87% and 96% for pH 5 and pH 6 respectively for the magnetized coupons, and, 80% and 94% at 0.95T and 1.51T respectively. Results were explained on the basis of the formation of paramagnetic Fe 2+ and Fe 3+ and the subsequent FeCl2 and FeCl3 species that adhered to the coupons as they become available in the system. This corrosion abatement technique using magnetized coupons to generate paramagnetic species in the electrolyte could be relevant in the oil industry. This could be specifically applicable to some crude oil and natural gas transporting pipelines that have CO2, H2S and microbes that generate corrosive acid media that will in turn produce paramagnetic species like FeCO3, FeSO4 and FeS.

Keywords: magnetized, mild steel, weight loss, laboratory electromagnet, pH, paramagnetic species.