BEHAVIOUR AT THE CORROSION OF COMPOSITE COATINGS OF LANTHANIDE OXIDES IN COBALT MATRIX

摘要

The composite coatings were obtained by electrodepostion in the cobalt metal matrix with lanthanide oxide such as: CeO_2, Nd_2O_3, La_2O_3 and Y_2O_3. The electrochemical aspects of the composite layers were studied by electrochemical impedance spectroscopy in order to establish the corrosion protection of the composite layers. The Co-CeO_2 composite coatings presents a good corrosion resistance in 0.1 M NaCl and this fact has been demonstrated by Rp high values obtained and by less Cp compared with pure cobalt and Co-Nd_2O_3, Co-La_2O_3 and Co-Y_2O_3 layers. The paper presents also investigation of corrosion protection for ECC Co-CeO_2, Co-La_2O_3, Co-Nd_2O_3 and Co-Y_2O_3 in the 3.5% NaCl by voltammetric measurements.