利用固体电解质定氧电池测定Fe-Nb熔体中铌的活度的研究

利用下列组装的固体电解质定氧电池:
Mo|Mo,MoO₂‖ZrO₂(MgO)‖[Nb],NbO₂|Mo+ZrO₂金属陶瓷,Mo对Fe-Nb熔体中Nb的活度在三个温度下(1823、1853及1873K)进行研究。在净化的氩气气氛下,将固态NbO₂细粉撒布在含铌铁液之上,以取得[Nb]与[O]的反应迅速达到平衡。有时不加任何固体料,使熔体中形成的脱氧产物自己上浮,此脱氧产物热力学证明是NbO₂。对测定的a₀实验数据进行加工处理,求出下列结果:
1.脱氧反应的自由能
[Nb]+[O]=NbO₂(s); △G°=-89710+28.27T
2.Nb在铁液中的溶解自由能
Nb_(s)=[Nb]_%; △G=-32090+7.9T; γ_{$mathop 1limits^{rm{^circ }} $873}=1.60
Nb_(l)=[Nb]_%; △G°=-38520+10.24T;γ_{$mathop 1limits^{rm{^circ }} $873}=0.92
3.Nb本身的活度相互作用系数
${rm{e}}_{{rm{Nb}}}^{{rm{Nb}}} = frac{{2274}}{{rm{T}}} - 1.44$
1873K的${rm{e}}_{{rm{Nb}}}^{{rm{Nb}}} = - 0.22$
当（Nb）含量大约低于0.2时，脱氧产物和其他合金元素如Al、Cr、V等相似，形成了复合氧化物如FeO·NbO₂。后者的生成自由能估计为：
Fe₍₁₎+$frac{3}{2}$O₂+Nb_(s)=FeO·NbO_2(s);△G°=-383800+121.95T
随着熔体中(Nb)含量的继续下降，对生成其他脱氧产物的可能性，本文也进行了讨论。

A Study of the Activity of Niobium in Molten Iron by the Solid Electrolyte Oxygen Cell Technique

The activity of Nb in molten iron was studied at three temperatures, 1823, 1853 anp 1873K with the solid electrolyte oxygen cell technique, the following cell assembly being adopted:
Mo, Ho + ZrO₂ Cermet|Mo.MoOt||ZrO₂ (MgO)||(Nb), NbO₂|Mo To equilibrate the (O) Content of the Nb-containing iron, Pure Solid NbO₂ particles were scattered over the surface of the melt under Purified argon atmosphere, and in some cases, the surface of the melt was left bare under the purified argon atmosphere, the oxide, which was ascertained thermodynamically as NbO₂, being formed by itself as the deoxidation product. By elaboration with the experimental data of a₀ determined, the following results were achieved:
1. The free energy of the reaction of deoxidation:
[Nb]+2[O]=NbO_2(S); ΔG°=-89710 + 28.27T
2. The free energy of sulution of Nb in iron:
Nb_(s)=(Nb)%; ΔG°=-32090 + 7.9T;γ_{$mathop 1limits^{rm{^circ }} $873}=1.60
Nb_(l)=(Nb)%l ΔG°=-38520 + 10. 24T,γ_{$mathop 1limits^{rm{^circ }} $873}=0.92
3. The self activity interaction coefficent of Nb:
${rm{e}}_{{rm{Nb}}}^{{rm{Nb}}}=frac{{2274}}{{rm{T}}}-1.44$
When the (Nb) content in the iron was less than about 0.2%, similar to the behavoir of other alloying elements such as Al. Cr, V etc, a complex oxide, probably FeO · NbO₂, was formed. The free energy of this complex oxide from its elements was estimated to be:
Fe₍₁₎+$frac{3}{2}$O₂+Nb_(s)=FeO·NbO_2(s);△G°=-383800+121.95T
The possibility Of the presence of other deoxidation products, as the (Nb) content in the molten Iron was decreased still further, was also discussed.