Shi Jun Wang

Kinetics of Microwave-Assisted Reduction of Manganese Oxide

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.

Melting Properties of Preparing Compound Desulphurizer by Aluminothermy Reducing Caustic Calcined Dolomite

Taken caustic calcined dolomite based compound desulfurizer as the research object, influence of fluxing agent CaF2, Al2O3, SiO2 and heating agent on the melting temperature of the compound desulfurizer was mainly investigated during its directly reducing process. Fluxing agent SiO2 and heating agent are the main influence factors, which influence melting temperature of the compound desulfurizer, the next are CaF2 and Al2O3. The mean value of compound desulfurizer melting temperature is respectively 1190.3°C and 1199Subscript text.1°C when the addition amount of SiO2 and heating agent is respectively 8.33% and 33.55%. With the increase of CaF2, the mean value of compound desulfurizer melting temperature decreases gradually, however, which increases first and then decreases with the increase of Al2O3.The conditions of the lowest melting temperature about the compound desulfurizer is A4, B1, C1, D2, namely 9% CaF2 + 0% Al2O3 + 8.33% SiO2 + 33.55% heating agent.

Study on Metal Thermal Reduction of Caustic Calcined Dolomite Based Compound Desulfurizer

Caustic calcined dolomite based compound desulfurizer by the aluminum thermal reduction was taken as study object. Effect of fluxing agent, reaction time and experimental temperature on the weightlessness of compound desulfurizer was studied. The result showed that the weightlessness of compound desulfurizer decreases slightly with the increase of fluxing agent CaF2 content. When the content of SiO2 changes from 12% to 20%, the weightlessness of compound desulfurizer which is basically about 27.5% changes a little. With the increase of experimental temperature and reaction time, the weightlessness of compound desulfurizer is gradually increased. When the reaction time and temperature is respectively 20min and 1300°C, the weightlessness of compound desulfurizer is 31.80%.

Effect on Inclusion and Microstructure of Ultra-Low S and Low P Steels with Vacuum Treatment

The simultaneous desulphurization and dephosphorization of molten steel with CaO-based slag containing BaO for vacuum treatment, and inclusion in steel and microstructure of steel are carried out separately. These results show that desulfurization rate exceed 92% and dephosphorization rate exceed 50% , final [S] content and [P] content in molten steel are less than 0.0024% and 0.020% respectively for all heats, and the lowest final [S] content and [P] content are 0.0012% and 0.010% respectively, they satisfy the demand of ultra-low S steels and low P steels; Comparing a grade 1.5 of inclusion level of the compared sample without vacuum treatment, inclusion level of these treated samples with vacuum is all less than grade 1.0 and that is less than grade 0.5 for 78% of treated samples; And micro-structure of the compared sample is ferrite + pearlite in steel base, but micro-structure of these treated samples is all needle-like ferrite + pearlite + netted ferrite in steel base and netted ferrite + pearlite in local area. This kind of fiber structure which comes from netted ferrite + needle-like ferrite and grade 0.5 of inclusion level can make steel possess better mechanical properties.

Performance of Anti-Erosion and Anti-Oxidation of High Al Steels at 1373K

The effect of Al content on the anti-erosion and anti-oxidation performance of high Al steels at 1373K is studied in this paper. By 168-hour heat treating at 1373 K and at oxidation atmosphere, These results show that for comparing non-Al steel and low-Al (w[Al]=1.14%) steel sample there are a more obvious and easily-dropping oxidation layer in surface in 24 h , the average oxidation rate is up to 0.406 mg/(cm2.h), but for high Al steel, there is a thinner gray oxidation layer in surface and a more fast oxidation rate for w[Al]<5% sample , and there is a thin, close and yellow gloss film and the average oxidation rate is only 0.016 mg/(cm2.h) for w[Al]=8.46% sample. The average erosion rate is 0.096 mg/cm2.h in initial 24 h and thereafter the erosion is very slow. But there is a higher erosion rate and the average erosion rate is 0.594 mg/(cm2.h) in 6 % HCl solution for high Al steel sample and comparing non-Al steel. Accordingly high Al steel possesses a good performance of high temperature anti-oxidation and anti-erosion in NaCl solution.

Calculation of Phase Diagram of CaO-SiO2-Al2O3-MgO-B2O3 Refining Slag without CaF2

CaF2 is used in large quantity during refining of steel, which is harmful to environment to be found. There is more and more study on use of B2O3 in metallurgical progress. This paper studied the effects of MgO on melting performance of CaO-SiO2-Al2O3 ternary system and B2O3 on that of CaO-SiO2-Al2O3-MgO quaternary system by calculation of phase diagram. The result shows that MgO can expand the range of liquid phase of CaO-SiO2-Al2O3 ternary system while the effect on melting performance is little. B2O3 can also reduce the melting point of CaO-SiO2-Al2O3-MgO quaternary system in high CaO zone and in high Al2O3 zone. So the proper composition of MgO in refining slag are 5~8% and B2O3 below 8%.

Effect of Static Magnetic Field on Distribution of Elements in the Fe-S, Fe-Si, and Fe-Mn Alloys

Three binary Fe-based alloys Fe-S, Fe-Si, and Fe-Mn has been designed and melted in order to investigate the effect of static magnetic field on the migration behavior and distribution of the three elements during the solidification process in this study, and microstructure and chemical composition on the samples have been inspected by optical microscopy and Original Position Analysis technologies. It has been found that the magnetic field can effectively change the distribution of S, Si and Mn, and the migration behaviors of the three elements are different.

Effect of Pulsed Electric Field on the Distribution and Migration of P, S, and Si Elements of Fe-based Alloys

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.

Study on Effect of Pulse Electric Field on Solidification Process of Fe-C-S Alloy Melt

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.

Study on the Influence Factor of the Caustic Calcined Dolomite Based Compound Desulfurizer Melt Point

Caustic calcined dolomite based compound desulfurizer by the silicon thermal reduction method was taken as study object. Effect of fluxing agent and heating agent on caustic calcined dolomite based compound desulfurizer melting point was studied. The result showed that heating agent was the major influential factor for the melting point of compound desulfurizer, melting point of the compound desulfurizer gradually reduced with the increase of heating agent. Fluxing agents of CaF2 and SiO2 were the minor influential factors for the melting point of compound desulfurizer. The lowest melting point condition for the compound desulfurizer was：7% CaF2+11% Al2O3+17% SiO2 + 56% heating agent.