用化学平衡法研究Fe—Nb—C熔体的热力学

Thermodynamic Study of Fe-Nb-C Melts Using the Chemical Equilibrium Method

摘要: CO-CO₂混合气与Fe-Nb-C熔体和NbO₂（s）的平衡实验是在Al₂O₃或ZrO₂坩埚中进行的。实验表明,在1073～1273K间的低温下产生碳沉积是不可避免的。熔体上方的气相氧分压用固体电解质电池测定。与熔体中Nb成平衡的氧化物被确定为NbO₂（s）。测得1823K时反应Nb+O₂=NbO₂（s）的平衡常数K=6.31×10¹⁰,因此,可得反应的标准自由能:
ΔG°=-377150（J/mol）
求出了碳对Nb和Nb对碳的活度相互作用系数为:
\rme\frac\rmC\rmNb=-0.74;\rme\frac\rmC\rmNb=-0.092

Abstract: The equilibrium of gaseous CO-CO₂ mixture with liquid iron-Niobium-Carbon alloys and NbO₂(s) contained in Al₂O₃ or ZrO₂ crucible is discribed. It shows that the deposition of carbon is inevitable in the low temperature zone(from 1073 to 1273K). The equilibrium partial pressure of oxygen in gaseous on the surface of the melt has been determined with the solid electrolyte cell.The oxide in equilibrium with the niobium in the melt is considered to be NbO₂ (s). The equilibrium constant for the reactionNb + O₂=NbO₂ (s)at 1823K is:K=6.31×10¹⁰ therefore the standard free energy is
△G°=-377150 (J/mol)
The interaction coefficients of activity evaluated, are
\rme\frac\rmC\rmNb=-0.74;\rme\frac\rmC\rmNb=-0.092.