DOPPSOND

摘要

An immersion-probe for use in the electro-chemical determination of the activity of elements, such as oxygen dissolved in a metal melt comprises a metallic carrier-core (1a) in the form of a wire or tube, a reference system in the form of a layer (2) surrounding the carrier-core (1) and a solid electrolyte in the form of a further layer (3) surrounding the layer (2). Preferably the layer (3) is further surrounded by a protective metal casing which melts in use. The layer (2) forming the reference system consists of particles of metal and of metal oxide in uniform distribution so that in the case of oxygen measurements a partial pressure of oxygen exists throughout the reference system at the boundaries between the particles of metal and the particles of metal oxide. A thermocouple 5 may provide in tube 1a.