The reduction rates of manganese oxide by carbon and SiC was examined by heating MnO2-carbon and MnO2-SiC mixtures in a 7-kW industrial microwave oven. The results show that the rate of the reduction increased with the amount of carbon in MnO2-carbon mixture and with SiC in MnO2-SiC mixture. The rate of the MnO2 reduction by carbon was proportional to the reaction time, and that by SiC was proportional to 2/3 power of the reaction time. The reduction was found to be controlled by chemical reaction. The reaction rate constant of the reduction of MnO2kC increased with increasing the amount of carbon in the mixtures but kSiC decreased with increasing the amount of SiC in the mixtures.
In this study, the structure, viscosity characteristics, and crystallization behavior of CaO-SiO2-B2O3 based melts were studied combining molecular dynamics (MD) simulation, Fourier transform infrared (FTIR) spectroscopy, rotating viscometer test, and FactSage thermodynamic calculation. The results showed that, in the ternary CaO-SiO2-B2O3 glass system, stable structural units of [SiO4]4− tetrahedral, [BO3]3− trihedral and [BO4]5− tetrahedral were formed, and the Si-O and B-O structure depolymerize with the basicity increase from 1.15 to 1.25, then the B-O structure become complex with the basicity further increase to 1.35. In fluorine-free mold fluxes, with the basicity increases, the viscosity at 1300 °C increases, the liquidus temperature decreases and then increases, the network structure polymerizes, it indicates that the structural complexity rather than the melting property change plays a predominant role in increasing the viscosity at 1300 °C. Moreover, due to the changes in crystallization phase and solid solution ratio, the viscosity-temperature curve of fluorine-free slag shows the characteristics of alkaline slag and the break temperature increase with the basicity increase. The MD simulation, FTIR experiment, viscosity test, and FactSage calculation results are verified and complemented each other.
The experiment has studied the effect of solidification process of Fe-C-S alloy treated RE on the distribution of elements and inclusions on the distribution of elements and inclusions after the electric pulse field is applied. The results show that Rare Earth in the molten steel has played a purification role and change the strip MnS inclusions into spherical sulfide inclusions. Meanwhile, the co-action of electric pulse field and Rare Earth can reduce and refine inclusions and improve the distribution of elements in solidification microstructure.
Pulsed electric field has been effectively used to control and modify the solidification process in castings. In this study, a pulsed electric field at 8 volts and 19 kHz has been applied to Fe-P, Fe-S, and Fe-Si binary alloys, and microstructure and elements distribution of the three alloy samples have been inspected. The results indicated that P migrated from cathode to anode while S and Si migrated from both electrodes to the center under the pulsed electric field during the solidification process.
It can reduce the grain boundary segregation effectively, and improve the solidification microstructure, as well as cause the migration and redistribution of elements by adding the pulse electric field during the solidification process of the Fe-C-S alloy melt. Where, the element S migrates from the positive polarity to the negative polarity, while the migration law of the element C is reverse to that of the element S. The principal ingredient of the inclusion in solidification microstructure after treatment is FeS and a small amount of MnS, while FeS is distributed at the edge and in the centre area of the whole sample spherically.
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