Polymer shield against corrosion
doi:10.1038/nindia.2008.219 Published online 10 June 2008
Researchers have invented a co-polymer coat that checks the corrosion of steel in acidic medium1. The co-polymer could find use in a host of industrial applications.
Mild steel is one of the important iron-containing alloys used in many industrial aqueous systems. Steel is generally coated with a zinc layer and a rinse of chromate-containing agents before smearing it with the protective coating. But, use of such heavy metals increases environmental concerns. This led the researchers to devise a non-toxic co-polymer made from maleic anhydride and N-vinyl-2-pyrrolidone. The end product was a co-polymer coat called VPMA (maleic anhydride-N-vinyl-2-pyrrolidone).
The researchers studied its efficiency by dipping mild steel pieces in a sulphuric acid solution in the absence and presence of various concentrations of VPMA. The experiments were carried out at different temperatures between 25-50°C.
Corrosion decreased with increasing VPMA concentration. The corrosion protection was mainly due to the interaction of VPMA which blocked the active sites of the metal surface. The adsorption of copolymer onto the steel surface led to the formation of a surface film that formed a barrier between metal and acid.
"The polymer can overcome environmental concerns and provide higher corrosion resistance to the base metal," says lead researcher Yanjerappa Arthoba Naik from the School of Chemical Sciences, Kuvempu University, Karnataka. The modification of metal towards corrosion inhibition by the polymer is a cheaper method, adds Naik.
- Achary, G. et al. An electroactive co-polymer as corrosion inhibitor for steel in sulphuric acid medium. Appl. Surf. Sci. 254, 5569-5573, (2008)