Corrosion inhibition effect of 1-phenyl-5-mercaptotetrazole on nickel-aluminum bronze in seawater: A combined experimental and theoretical study

A combined experimental and theoretical study was performed on corrosion inhibition effect of 1-Phenyl-5-mercaptotetrazole (PMT) on nickel-aluminum bronze (NAB) in seawater. Gravimetric measurement and electrochemical method, such as the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), Tafel polarization curve were used to verify the corrosion inhibition effect of PMT. It was found that the corrosion inhibition efficiency (IE) of PMT achieved 94.4 %, 99.5 %, 98.7 % at a concentration of 1.12 mM, respectively. The slump of the degree of corrosion on NAB surface was also revealed based on SEM and AFM images analysis with the addition of PMT. According to the Langmuir isotherm model based on EIS, PMT was confirmed as a mixed-type corrosion inhibitor between -20 kJ mol-1 and -40 kJ mol-1. Besides, the successful adsorption of PMT on NAB has been revealed by the results of XPS and the change of water contact angle on NAB surface. In combination XPS with quantum chemistry calculations, PMT molecules are adsorbed on the surface of NAB by the active S atom and the tetrazole ring as the major adsorption groups, thus, the protective barrier formed by PMT on the surface of NAB can effectively insulate NAB from contact with seawater. The research results in this paper have showed that PMT as a drug intermediate has an excellent corrosion inhibition effect on the NAB at extremely low concentration in seawater.