전기화학적 방법에 의한 Cobalt/Zinc Oxide의 증착에 관한 연구

초록

Functional composite coatings of a metal matrix with different metal oxides are used as corrosion protection coatings and catalysts. Previous works showed that metal were electrodeposited in the oxide-dispersed solution and the amount of oxide in the deposit were was strongly dependent on the concentration of oxides in the electrolyte. This work presents the Co-ZnO co-deposition in a single bath solution, CoSO4 + Zn(NO3)2. In a single Zn(NO3)2 solution, cathodic polarization and the characterization of deposits indicated the formation of ZnO which resulted from the pH increase during reduction. However, metal Co is cathodically deposited in a CoSO4 solution and, on the other hand, Co, Co(OH)2, Co2O3 was codeposited in a Co(NO3)2 solution. A cathodic linear sweep voltammetry in a mixture CoSO4 + Zn(NO3)2 showed a sharp current peak(IP) at -1.0V which suggested the passivation of metal cobalt due to NO3- reduction. Potentiostatic deposition was made in different potentials ranging from -0.8V to -1.2V. At potentials below -1.0V, Co was deposited and cathodic current increased slowly during an incipient period. However, cathodic current increased rapidly and returned to the steady state value. Transient time span decreased with the increase of applied potential and it can be interpreted with the phase changes of deposited materials. Accompanied morphological and structural variations during electrochemical composite coatings were investigated.