An electrochemical meter for measuring carbon activity in liquid sodium

Abstract

This paper reports the development of an improved electrochemical carbon meter which gives better long term performance compared to similar meters described by earlier workers. The initial problem of the meter was identified to be due to decarburization of the Fe/Fe₃C reference electrode. The new reference electrode consisting of a graphite-filled nickel capsule was found to give satisfactory performance. However, the test in commercial grade sodium did not give the expected temperature dependance of emf values. This is attributed to the influence of carbon bearing impurity species present in commercial grade sodium. Experiments with purified sodium gave emf response with change in temperature in accordance with the established solubility relationship of carbon in sodium. The long term test of performance of the meter in liquid sodium is described. Its utility for measuring the carbon activities of various metal carbide systems is also pointed out.