Ceramics-Silikáty 24, (1) 1 - 6 (1980) |
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THE EFFECT OF PARTIAL OXYGEN PRESSURE ON THE TEMPERATURE OF β TO α CALCIUM CHROMITE TRANSFORMATION
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Havlica Jaromír, Pánek Zdeněk
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Institute of Inorganic Chemistry, Slovak Academy of Sciences 809 34 Bratislava, Dúbravská cesta 5
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The temperature of modification transformation of β to α calcium chromite was studied in air atmosphere, in argon and in a CO-CO2 mixture. It was found that in air the modification transformation takes place at 1720 °C and that the transformation temperature Tp decreases with decreasing partial pressure of oxygen in the gaseous phase according to the relationship
Tp = (6.28 × 10⁵)/(319.4 ⁻ logpO₂) (Tp [K], pO₂ [Pa]).
A comparison of the data obtained with previous results has shown that when the partial pressure of oxygen is reduced the minimum transformation temperature is 1645 °C. Below this temperature and at lower partial pressures of oxygen β-calcium chromite is reduced and chromium metal is separated.
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