Abstract

Mild steel is economical metal so it is used in different appliances of industries, railways, bridges, construction works and marine water. Marine water produces corrosive environment for this metal. Marine water is saline in character so it corrodes mild steel. Polybutadiene is coated on the surface of mild steel for corrosion protection. But this coating does not provide sufficient protection of base metal. Marine water is major absorber of CO₂. It converts CO₂ into H₂CO₃. Saline water and H₂CO₃ interacts with polybutadiene-coated mild steel and they exhibit chemical and electrochemical reactions. This chemical reaction produces swelling and dissolving corrosion and produce disbonding between carbon and carbon of polybutadiene. These corrosive agents show osmosis or diffusion process and inter inside the base metal and develop corrosion cell. Metal generates corrosion reaction which produces several forms of corrosion like galvanic, pitting, crevice, stress, intergranular, blistering and embrittlement. For the protection from such types of corrosions synthesized organic compounds octahydrodibenzo[a,d][8]annulene-5,12-dioxime was used and this compounds was nanocoated on the surface of polybutadiene-coated mild steel. During nanocoating used compound developed lot of porosities on the surface of polybutadiene-coated mild steel and they were blocked by the use of filler materials ZnS. The corrosion rate of material was calculated by gravimetric and potentiostat. Composite barrier formation was analyzed by activation energy, heat of adsorption, free energy, enthalpy and entropy. The results of surface coverage area and coating efficiency were indicated that compound octahydrodibenzo[a,d][8]annulene-5,12-dioxime and ZnS have good coating and filling properties.