二，三の金属とＮａ?S２?TＯ・２Ｂ?S２?TＯ?S３?Tガラス融液との分極下における反応について

Abstract

The knowledge about the electrochemical behavior of various metals in molten glasses during voltage application is essential to electric melting of glass.In this paper, the anodic dissolution, passivation and cathodic deposition of metals were investigated in molten sodium diborate glass by linear potential sweep method. As the electrodes, metals such as Pt, Ni and Fe were selected. The relationship between current and applied potential was determined at various linear potential sweep rates (0.001∼5V/sec) between 0∼±5V by using platinum wire as a reference electrode and an auxiliary electrode under N2 atmosphere.By anodic potential sweep of Pt electrode, S shape current-potential curves were obtained at various potential sweep rates. This limiting current might be attributed to the diffusion current of oxygen ions. When the applied potential was more than ca. 3V, the oxygen gas evolution was observed because of electrolysis of the solvent glass. Pt electrode acted as an insoluble electrode.Due to anodic polarization, Ni electrode dissolved as soon as a potential was applied, but the dissolution current decreased suddenly at a certain voltage. The respective plots of the peak currents and peak potentials against (potential sweep rates)1/2 were shown to be straight lines. These phenomena can be explained by coverage of the electrode surface by poor conductive oxide films formed by the reaction, Ni+O2-=NiO+2e. There was no peak on the current-potential curve for Fe electrode and Fe dissolved rapidly.