Oxygen pressure dependence of tracer diffusivities of ca and fe in liquid CaO-SiO-FeO system.

The tracer diffusivities of calcium and iron in a steel-making slag of 33 pct CaO-27 pct SiO-40 pct FeO by charge composition have been measured at 1360 to 1460°C as a function of temperature and oxygen pressure in the gas phase. The results expressed in cm/s (in SI unit of m/s, the following equation should be divided by 10,000) are given by where for tracer diffusion of iron, D is 0.2, x is 8.5, and E is 26 kcal/mol (1.09 x 10 J/ mol) and for tracer diffusion of calcium, D is 0.1, x is 12.5, and E is 28 kcal/mol (1.17 x 10 J/mol). Prior to diffusion runs, the slag was equilibrated with the gas mixture of carbon monoxide and dioxide with an oxygen pressure of 10 to 10 atm. The diffusivity was measured by the instantaneous plane source method, using radioactive tracers of calcium and iron. The increase of the tracer diffusivities with the oxygen pressure was interpreted in relation to a probable increase of the divalent cation vacancies in the slag. [ABSTRACT FROM AUTHOR]