Probe for monitoring oxygen activity of molten materials - is made of sintered conducting refractory oxide core covered by solid electrolyte

摘要

The probe consists of a comparison substance (a) of known oxygen activity, which is sintered to form a solid, metallically-conducting core(a) covered by a solid electrolyte (b) at least in the zone of the probe (a,b) which is immersed in the melt. Layer (b) is pref. 40-250, (50-150) mu m thick, with total porosity 20-45 esp (30)%. The probe is pref. made by mixing a refractory oxide powder (a1) with carbon or graphite powder and a binder (a2), followed by moulding or extruding to make a core which is sintered so the carbon reduces some oxide (a1) to form over 30 wt% metal. Oxide (a1) is pref. Cr2O3 or MoO2; and binder (a2) is pref. synthetic resin resol or novolak with hexamethylene. Layer (b) is pref. ZrO2 with CaO, MgO and/or Y2O3; ThO2 with Y2O3; 3Al2O3, ZSiO2(mullite); or Mg-Al-spinel. The probe is simple to mfr. but has a long working life, as it does not crack due to thermal shock.