Development of electrochemical sensor for rapid measurement of solute activities using mullite solid electrolyte

1.It was confirmed from the measurement of formation free energy of oxides (FeO,CoO,NiO) by usingtablet of mullite (3al_2o_3、2sio_2) that mullite could be used as a solid electrolyte.2.The valuesfor electronic conductivity limits, p_ <THETA>，of mullite and zro_2 -9 mol% MgO solid electrolytes were estimated as log(p _< theta >/ atm)= 54.32 -137000 / t and半决赛(p _< theta >/ atm)= 27.16 -75500 / t, respectively / 3 . the values foroxygen activity obtained using a mullite or zro_2 -plug类型probe agreed satisfactorily with boththose calculated from the Al/ al_2_3 equilibrium and those estimated from the analyzed oxygencontents. The values for oxygen activity obtained using a zro_2 -tube type probe were higher thanthose estimated from the analyzed oxygen contents. A polarization effect in A zro_2 -tube type probe4.From superaturation experiments，不能在低oxygen activity中使用的方法它可以包含一个方法EMF by a mullite probe corresponded to the oxygen activitydetermined bt the Al/ al_2_3 (in mullite) equilibrium at liquid iron/electrolyte interface，while that of a zro_2 -plug类型probe corresponded to the supersaturated oxygen activity.5. theactivity of silicon in Fe-Si alloys equilibrated with sio_2 itwere determined by a mullite orzro_2 -plug类型probe. Both results agreed well with each other. The activity of silicon incarbon-saturated Fe-Si alloys obtained by a mullite probe agreed with those calculated from the分析silicon contents. The measured EMF by a mullite probe corresponded to The oxygen activitydetermined bt the Si/ si0_2 (in mullite) equilibrium at liquid iron/electrolyte interface.6.Sincethe measured EMF by a mullite probe corresponded to the aluminum or silicon activity not to theoxygen activity in bulk，它可以包含一个mullite solid electrolytecould be used for Al-or Si-sensor in liquidmetal。

1.It was confirmed from the measurement of formation free energy of oxides (FeO,CoO,NiO) by using tablet of mullite (3Al_2O_3・2SiO_2) that mullite could be used as a solid electrolyte.2.The values for electronic conductivity limits, P_<THETA>, of mullite and ZrO_2-9 mol% MgO solid electrolytes were estimated as log (P_<THETA>/atm)=54.32-137000/T and log (P_<THETA>/atm)=27.16-75500/T,respectively/3.The values for oxygen activity obtained using a mullite or ZrO_2-plug type probe agreed satisfactorily with both those calculated from the Al/Al_2O_3 equilibrium and those estimated from the analyzed oxygen contents. The values for oxygen activity obtained using a ZrO_2-tube type probe were higher than those estimated from the analyzed oxygen contents. A polarization effect in a ZrO_2-tube type probe could not be eliminated in the measurement of low oxygen activity.4.From superaturation experiments, it could be concluded that the measured EMF by a mullite probe corresponded to the oxygen activity determined bt the Al/Al_2O_3 (in mullite) equilibrium at liquid iron/electrolyte interface, while that of a ZrO_2-plug type probe corresponded to the supersaturated oxygen activity.5.The activity of silicon in Fe-Si alloys equilibrated with SiO_2 itwere determined by a mullite or ZrO_2-plug type probe. Both results agreed well with each other. The activity of silicon in carbon-saturated Fe-Si alloys obtained by a mullite probe agreed with those calculated from the analyzed silicon contents. The measured EMF by a mullite probe corresponded to the oxygen activity determined bt the Si/SioO_2 (in mullite) equilibrium at liquid iron/electrolyte interface.6.Since the measured EMF by a mullite probe corresponded to the aluminum or silicon activity not to the oxygen activity in bulk, it could be concluded that a mullite solid electrolytecould be used for Al-or Si-sensor in liquid metal.