La传感器及其在碳饱和铁液与凝固中La活度的研究

PREPARATION OF La SENSOR AND DETERMINATION OF La ACTIVITY IN C-SATURATED MELTED IRON AND ITS SOLIDIFICATION PROCESS

制得多晶Ｌａ_（０．９５）Ｃａ_（０．０５）Ｆ_（２．９５）固体电解质管，以纯Ｌａ作为参比电极，组成Ｌａ传感器电池形式为：Ｍｏ｜Ｌａ（１）ｏｆ（ｓ）｜Ｌａ_（０．９５）Ｃａ_（０．０５）Ｆ_（２．９５）｜［Ｌａ］Ｆｅ｜Ｍｏ金属陶瓷。于１５７３Ｋ测定了碳饱和铁液中不同Ｌａ浓度下熔解态Ｌａ的活度，与同时用氧传感器测得的氧的变化规律相符合追踪测定了１６２３Ｋ碳饱和铁液凝固过程中溶解态Ｌａ活度随温度的变化，结果呈现规律性Ｌａ传感探头在降温和升温过程中可连续使用。

The La sensor was composed of polycrystalline La0.95Ca0.05Fz.gs as solid electrolyte, pure La as reference electrode and Mo wire as lead wire. It can be expressed as:Mo|La(1)or (s) |La0.95 Ca0.05F2.95|[La]Fe Mo ceramal. The activity of dissolve La in C-saturated melted iron (1300℃) with different La concentration was detennined. The result was in agreement with that of O2 concentration cell e.m.f determined by O2 probe. The activity change of La with temperature in the solidified process (from 1350℃) was also determined and shows regularity. With the temperature changing from 1350℃ to 600℃, the activity of La varied from 10￣(-4) to 10￣(-20)