Corrosion inhibition of Ti-6Al-4V alloy in methanolic sulphuric and hydrochloric acid solutions using Bradoral

摘要

THE CORROSION behaviour of Ti-6Al-4V alloy in 2.5M H_2SO_4 and 5.0M HCl solutions containing different concentrations of methanol was investigated using polarization and electrochemical-impedance spectroscopy (EIS), The corrosion rate of the alloy was found to decrease with increasing alcohol content in the acid solution. Also, the effect of a cationic surfactant--such as Bradoral--on the corrosion rate of the alloy in methanolic sulphuric and hydrochloric add solutions was studied. The corrosion inhibition efficiency at different concentrations of the surfactant was calculated: it turned out that Bradoral has a maximum corrosion inhibition efficiency for the alloy at a concentration of 7.5 X 10~(-4)M in 2.5M H_2SO_4 and 7.5 X 10~(-3)M in 5.0M HCl. Scanning-electron micrographs indicated that the patches and flawed regions on the alloy surface were reduced greatly in the presence of Bradoral. The activation energy values of alloy corrosion in methanolic 2.5H H_2SO_4 and 5.0M HCl solutions were found to be 69 and 56kJmol~(-1), respectively.