MEASUREMENT OF CALCIUM CONTENTS IN MOLTEN NICKEL BY USING OXYGEN SENSOR WITH AUXILIARY ELECTRODE

A sensor to determine calcium contents in molten metal is examined. Th e sensor is constituted of an oxygen sensor with an auxiliary electrod e which is surrounded with a cap made of silica. 0.02 to 0.1 mass% of calcium contents in molten nickel can be detected by the sensor. Relat ion between calcium contents in the molten nickel and electromotive fo rces of the sensor can be expressed as following equation : EMF/mV=-17 3log[%Ca]-423+/-18 According to discussion on the basis oi thermochemi stry, it is revealed that the sensor acts as a chemical sensor of whic h output is determined by the thermochemical relation between calcium and oxygen.