Determination of the Oxygen Content after Silicon Deoxidation by the Herty Method

Abstract

Changes of the oxygen content in liquid iron after silicon addition have been determined by fixing the oxygen as Al₂O₃ with thin aluminum wire previously charged in the sampler and chemically analyzing the aluminum content of the inclusion which is a mixture of Al₂O₃ and SiO₂.
The results obtained arc as follows:
(1) The oxygen values at a certain time after silicon addition are independent of the amount of aluminum charged in the sampler and the kind of the sampler used.
(2) The oxygen content gradually decreases and reaches to the equilibrium value.
From these results and the calculation about the reduction of SiO₂ particles with aluminum in molten iron, it has been confirmed that besides SiO₂ particles (>1 μm), a large number of minute SiO₂ (<<1 μm) exist in liquid iron and a part of them remains to the last stage of the deoxidation process.
The result that the melt is super-saturated with oxygen untill the equilibrium is reached, is explained by the fact that the minute SiO₂ are easily reduced by aluminum during solidification of the sample.