S. Divakara Shetty

INHIBITION OF MILD STEEL CORROSION IN ACID MEDIA BY N-(2-THIOPHENYL)-N/-PHENYL THIOUREA

The corrosive behavior of mild steel in 0.05 M and 0.1M HCl, 0.025 M and 0.05 M H2SO4 solutions containing different concentrations of N-(2-thiophenyl)-N/-phenyl thiourea (TPTU) was investigated using potentiodynamic polarization technique. The results obtained reveal that TPTU is an efficient anodic inhibitor in the acid environment and it is more effective in reducing corrosion of mild steel in HCl than in H2SO4 media. The adsorption of the inhibitor on the mild steel surface in both acids obeys the Temkins’ adsorption isotherm. The thermodynamic parameters of adsorption deduced reveal a strong interaction and spontaneous adsorption of TPTU on the mild steel surface. The influence of temperature and inhibitor concentration on the corrosion of mild steel has also been investigated.

INHIBITING EFFECT OF N-CYCLOHEXYL-N′-PHENYL THIOUREA ON THE CORROSION OF 304 SS IN HYDROCHLORIC ACID SOLUTION

The inhibiting action of N-cyclohexyl-N′-phenyl thiourea (CPTU) on the corrosion behavior of 304 SS in 3 M hydrochloric acid solution has been investigated using potentiodynamic polarization technique at four different temperatures. The results obtained reveal that CPTU acts as an efficient anodic inhibitor for the corrosion of 304 SS. Good inhibition efficiency (>92%) was evident in the acidic solution, and it was found to vary with temperature and concentration of the inhibitor. The adsorption of this compound on the 304 SS surface was found to obey the Temkin adsorption isotherm, and the inhibition was governed by physical adsorption mechanism. The thermodynamic parameters of adsorption deduced revealed a strong interaction and spontaneous adsorption of CPTU on the steel surface. Scanning electron microscopic study (SEM) was done to investigate the surface characterization of inhibited and uninhibited 304 SS specimens.