Inhibition effect of Thiadiazole Piperidine and Oxadiazole derivatives on brass corrosion in natural seawater

Abstract

Copper and its alloys are widely used in marine environments due to their corrosion resistance, mechanical workability, excellent electrical and thermal conductivities and good resistance to biofouling. Brass is used extensively in marine applications and in heat exchanger tubes, for example in desalination and power generation, respectively. The dezincification of brass has attracted the attention of researcher for some decades and is still the subject of increasing attention. It is particularly relevant to India possessing larger coastal area where various industries extensively use brass in desalination, power generation and cooling water systems. In the present study, the corrosion inhibition and dezincification performance of some alkyl substituted thiadiazole derivatives on brass in natural seawater have been investigated by potentiodynamic polarisation and the electrochemical impedance spectroscopic (EIS) measurements. The adsorption of the inhibitors on the brass surface in natural seawater obeyed Langmiur adsorption isotherm. Inductively Coupled Plasma Atomic Emission Spectroscopic (ICPAES) measurement was used to determine the extent of metal ions viz: Cu and Zn leached out from the brass during the polarisation experiments in the absence and presence of optimum concentration (10-3 M) of the studied thiadiazole, piperidine and oxadiazole derivatives. ICP-AES analysis revealed that the investigated inhibitors effectively control the dezincification of brass. The passive film formed on the surface of the brass was characterised by Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDX) and Scanning Electron Microscopy (SEM). FT-IR spectra showed that the protective film consists of the studied thiadiazole, piperidine and oxadiazole derivatives. SEM and EDX analysis showed that the inhibitor film is formed on the brass surface, which prevents the growth of oxides and chlorides of Cu and Zn. newline