Using a lime crucible and an induction furnace in vacuum as well as at pressure, a study was made to clarify the deoxidation and the desulphurization processes of liquid iron and iron-base alloys by iron clad calcium or aluminium alone.
The experimental results are summarized as follows.
(1) Calcium addition to liquid iron in a magnesia or alumina crucible greatly influenced the rate of deoxidation and the deoxidizing power owing to the reaction of the crucible material with calcium.
(2) The CaO-FeO oxide which was formed for liquid iron in a lime crucible immediately after the calcium addition seemed to grow and to be separated from the melt with time.
(3) At 1 600°C in 1 atm argon, the concentration of calcium dissolved in liquid iron was estimated to be 0.024 wt pct. The equilibrium constants were calculated as follows. log K_ca=log a_ca.a_o=-8.23 and K′_ca= [%Ca]×[%O] =2.16×10^-6,
(4) It is presumed that the aluminium desulphurization of liquid iron in a lime crucible is caused by the formation of highly basic reaction product layer such as 3CaO.Al₂O₃ on the surface of the crucible.