Corrosion inhibition effect of 2,5-bis (3,4,5-trimethoxy phenyl)-1,3,4-oxadiazole (BTPO) on 18 Ni M250 grade welded maraging steel in 1.0 M sulphuric acid medium

Abstract

Corrosion inhibition of welded maraging steel in 1.0 M sulphuric acid was studied in the presence of different concentrations of 2,5-bis (3,4,5-trimethoxy phenyl)-1,3,4-oxadiazole (BTPO) by electrochemical techniques. The results confided that BTPO was a good inhibitor, and the inhibition efficiencies obtained from potentiodynamic polarization and electrochemical impedance methods were in good agreement. The inhibitor, BTPO, acted essentially as a mixed-type inhibitor with its inhibition action through its surface adsorption. The inhibition effciency was found to increase with the increase in BTPO concentration but decreased with the increase in temperature. The activation parameters for the corrosion of the alloy and thermodynamic parameters for the adsorption of BTPO on the alloy surface were calculated and discussed. The adsorption of BTPO on welded maraging steel surface was predominantly through physisorption and obeyed the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) study confirmed the formation of an anticorrosion protective film of BTPO on the metal surface.