Corrosion and corrosion inhibition of nickel in HClO4 solutions using the EQCM technique

Application of the electrochemical quartz crystal microbalance (EQCM) to th e study of metal corrosion and its inhibition is rather recent. Among the a dvantages of this technique are its very high sensitivity and the possibili ty of simultaneous mass variations and voltammogram recording. These charac teristics suggest the use of the EQCM for research in very low corrosion ra te conditions. This paper reports the results of EQCM measurements on the c orrosion inhibition rates of Ni in 0.1 M HClO4, in the absence and presence of different inhibitors in free corrosion conditions, for following inhibi tors: acridine (A), benzyl quinolinium chloride (BQCl), dodecyl quinolinium bromide (DDQBr), tributylbenzyl ammonium iodide (TBNI) and potassium iodid e (KI). The corrosion rate was reduced considerably by KI and TBNI. DDQBr s howed a good inhibitive efficiency, while BQCl had only a small effect, and A stimulated corrosion of the Ni. Voltammograms at different scanning rate s and the mass variation in the same solutions were recorded. Comparison of the current density and the mass changes provided the basis for a qualitat ive interpretation of the passivation of Ni and the mechanism of action of the different inhibitors.