Inhibition and polarization studies of titanium in sulphuric and hydrochloric acid solutions

Polarization and inhibition studies of Ti-Al-V alloy is 5N H2SO4 and 5N and 12N HCl solutions have been carried out at various temperatures. Effects of a number of organic and inorganic compounds have been tested on steady state free corrosion potential and on the anodic and cathodic polarization of the metal. The nitro organic compounds and noble metal ions have been found to passivate the metal and their effects have been sensitive to critical concentrations. Among the inhibitors studied, FE+, CU3+ and pictric acid are found to be most effective in moderate acid concentrations. In highly concentrated acid solutions, the inhibitors bring the free corrosion potential of the metal in passive state but passive dissolution current has been quite high. The magnitude of activation energy and the temperature coefficient indicate that the metal dissolution in acid solutions is chemically controlled rather than the diffusion controlled reaction. Chloride ion studied upto benzene have no effect on the free corrosion potentials of the metal in acid solutions. (Sarvashri D.D.N. Singh, M.K. Banerjee and P.S. Nag, National Metallurgical Laboratory