日本金属学会誌

J. Japan Inst. Metals, Vol. 39, No. 4 (1975),
pp. 388-393

On the Capacitance of Platinum Electrode in Na2O-SiO2 Melts

Masahiro Ashizuka1 and Keiz\=o \={Oe}2

1Kyushu Institute of Technology, Kitakyushu
2Graduate School, Kyushu Institute of Technology, Kitakyushu

Abstract:

The capacitance of platinum electrode in Na2O-SiO2 melts was measured by the alternating current bridge method in order to obtain the information on slag-metal interfacal structure.
The results obtained are as follows:
(1) Capacitance-potential curves measured by various frequencies (0.2 ∼ 2.0 kHz) have the maximum capacitance in the vicinity of -200∼-300 mV (vs Pt) and two minimum capacitances on both sides of the maximum capacitance, and abruptly rose above 200 mV on the anodic side and under -400∼-500 mV on the cathodic side.
(2) The capacitance-potential curve obtained by extrapolating to infinite frequency is parabolic with a hump at the natural electrode potential.
(3) Oxygen ion in melts is adsorbed on to the platinum electrode surface in the vicinity of the natural electrode potential indicating the minimum capacitance on the anodic side for various frequencies.
(4) Adsorption-desorption reaction of oxygen ion occurs in the vicinity of the potential indicating the maximum capacitance (-300∼-450 mV).
(5) The platinum surface is stripped by oxygen ion over the range of -300 to -450 mV and is occuppied by Na+ ion.
(6) The minimum capacitance extrapolated to infinite frequency and the maximum capacitance for several frequencies increase with increasing concentration of Na2O in slag.


(Received 1974/10/17)

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