Probe for continuous determn. of oxygen in melts - probe contg. stabilised zirconium di:oxide enabling longer period measurement and incorporating a thermocouple

摘要

Probe used for continuous electrochemical determn. of the O content of steel or iron melts consists of a ZrO2 case with a filling of a fine grain powder mixture of Cr/CrO3, Mo/MoO2, Ni/NiO, etc., and 30-50 wt.% stabilised ZrO2 powder. The probe also contains one of the two electrodes for the determn. of the O activity, the other is immersed into the melt. As the O content of the melt is derived from the O activity and the temp. a thermocouple is also incorporated into the ZrO2 case. Another version of the probe uses ThO2 and stabilised ThO2 powder instead of ZrO2. Conventional electrochemical probes become inactive after only a few secs. while the probe contg. stabilised ZrO2 powder of a fine grain size can be used for several hrs. This is of importance as the O level varies with the location in the melt and with time.