含クロム溶鉄と石灰系フラックス間のりんの分配平衡
1988 年 74 巻 5 号 p. 809-815
詳細
1988 年 74 巻 5 号 p. 809-815
In view that Fe-Cr-C melts should be dephosphorized preferably by CaO bearing fluxes for economical reasons, the lowest phosphorous content attainable in equilibrium by the treatment was estimated by measuring 1) the GIBBS free energy of formation of CaO·Cr2O3, which determines the maximum oxygen partial pressure and 2) phosphorous distribution between CaO-SiO2-CaF2 fluxes and Fe-Cr-C melts at 1 300°C.
The results are summarized as follows:
1) The Gibbs free energy of formation of CaO·Cr2O3 can be expressed by the following equation.
2Cr(s)+ CaO+ 3/2O2= CaO·Cr2O3
ΔG°=-1 350 000 + 344 T±10 000 J/mol
2) For effective dephosphorization of carbon saturated Fe-16%Cr melts the phosphate capacity of the flux must be higher than 1027.
3) The addition of a small amount of Na2O or BaO to CaO-SiO2-CaF2 fluxes saturated doubly with CaO and 3CaO·SiO2 was observed to increase significantly their dephosphorization capacity.
4) The interaction parameter ePCr was found to be -0.039 at 1 300°C.
