Activity Measurement of FeO?Cr₂O₃ in ‘FeO?(Cr, Al)₂O₃’ Solid Solution

摘要

Thermodynamic information on the equilibrium between dissolved Cr and O in steel melt is the basic knowledge to control Cr content in the stainless steel production process. In the case of using alumina refractories, molten Fe–Cr alloy equilibrates locally with ‘FeO?(Cr, Al)_(2)O_(3)’ solid solution at the interface between the melt and refractories when Cr content in the alloy is low. Wide composition range of ‘FeO?(Cr, Al)_(2)O_(3)’ solid solution is known, and the activity data of FeO?Cr_(2)O_(3) in ‘FeO?(Cr, Al)_(2)O_(3)’ solid solution is required to precisely estimate and control the Cr–O equilibrium relation in molten Fe–Cr when the alloy is produced in the furnace lining by Al_(2)O_(3) refractories. In the present work, crucibles made of ‘FeO?(Cr, Al)_(2)O_(3)’ solid solution were equilibrated with molten Ag under CO–CO_(2) gas mixture at 1873 K to determine the activity of FeO?Cr_(2)O_(3) in the solid solution.