Corrosion protection of stainless steel in 15% H SO 2 4

Abstract

Stainless steel is a very important industrial metal which is used in different appliances of phosphate fertilizer industries. Sulphuric acid is a major chemical to apply for manufacturing of fertilizers. This acid develops corrosion cell with stainless steel and accelerates internal and external corrosion reaction on surface of base metal. The used acid produces several forms of corrosion and change physical, chemical and mechanical properties of materials. Sulphuric acid creates corrosive environment for stainless steel and protection such acid attack used organic inhibitors 2-(aminomethyl) phenol and 2-(aminomethyl) benzenethiol and these inhibitors anticorrosive properties studied in 15% H SO medium. Inhibitors' action studied at different temperatures and 10mM 2 4 concentration. The corrosion rate of metal absence and presence of inhibitors were determined gravimetric and potentiostat techniques. The surface adsorption activities studied Langmuir isotherm. The results of potentiostat were shown that corrosion current density reduced after addition of inhibitors. Thermodynamical parameters of both inhibitors like activation energy, heat of adsorption, free energy, enthalpy and entropy were indicated thin film formed on the surface base metal which binds with physisorptionchemisorption adsorption. Thermodynamical parameters results showed that both inhibitors were good thermal and molecular stability on surface of base metal. The experimental results of surface coverage area and inhibition efficiency were exhibited that used inhibitors were highly effective in sulphuric acid medium.