Investigation of the inhibitive effect of N methyl thiourea on the corrosion of steel API X52 in 1 M HCl

The inhibition ability of N-methyl thiourea against the corrosion of steel X52 in 1 M HCl solution was evaluated by potentiodynamic polarization and scanning electron microscopy. Polarization studies indicated that N-methyl thiourea retards both the cathodic and anodic reactions through adsorption and blocking the active corrosion sites. The adsorption of N-methyl thiourea indicated the Langmuir adsorption isotherm. Thermodynamic and kinetic parameters such as enthalpy, activation energy and entropy were calculated. Gibbs free energy showed that the adsorption process is spontaneous. Scanning electron microscopy was used to study the steel surface. Surface studies show that the surface of sample in the presence of N-methyl thiourea looks more uniform with lower roughness than that in the uninhibited solution.