Study on Phase Diagram of Fe-Cr-O System

Abstract

To study the defect structure in tetragonal chromite, its density, thermogravimetic, property, electric resistance and thermo e. m. f. were measured.
Furthermore the influence of nitrogen or carbon on the formation of tetragonal chromite was studied.
The results obtained are as follows:
1) The effect of nitrogen or carbon on the formation of the tetragonal chromite was not determined.
2) Results from thermogravimetric studies have shown good agreement with those from X-ray studies.
3) Isothermal phase diagram of Fe-Cr-O system at 1 600°C was established. The relationshp between the chromium content of Fe-Cr melt and the oxide phase equilibrated was determined. below 1% Cr-cubic chromite, 1-7%Cr-c/a=1-0.95 above 7% Cr-Cr₂O₃
4) From single phase region of chromite, the chemical composition of chromite having axial ratio c/a=0.95 was determined as (Fe_0.26·Cr_0.74) _3.04O₄.
5) Defect structures in cuLic and tetragonal chromites were confirmed.