Decorative chromium plating durable against corrosion in chromium (III) solution containing isoniazid using electrocoating method

In this study, the electrodeposition of metallic chromium from trivalent chromium electrolytes (TB) containing isoniazide (INH) was investigated. The electrochemical behavior of Cr(III) in the TB containing INH on a glassy carbon electrode at 40 0C was researched by using cyclic voltammetry. The results obtained from the cyclic voltammetry showed that the electrodeposition of metallic Cr in the TB containing INH was an irreversible process and controlled by the diffusion of Cr(III) on a glassy carbon electrode. The average n value was calculated to be 0.314 and the diffusion coefficient value of Cr(III) was to be 1.06x10-5 cm2 s-1 at 40 0C. The other part of the study dealt with the electrochemical behaviors of coatings formed with different concentrations of INH in 0.1 M H2SO4 solution at 25 0C by using potentiodynamic polarization curves, electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS) techniques. The corrosion resistance of coatings increased greatly by adding a small amount of INH, whereas the excessive addition decreased the corrosion resistance. The results of the polarization curves, EFM and EIS showed that the coatings containing INH gave better corrosion resistance than the coating without INH.