Lithofacies structure of commercial cover flux and experimental slags were analyzed,and states of rare earth oxides in cover flux were studied. The results show that under the experiment conditions,the mineral structu...Lithofacies structure of commercial cover flux and experimental slags were analyzed,and states of rare earth oxides in cover flux were studied. The results show that under the experiment conditions,the mineral structures of original slags are mainly the calcium feldspar,a lot of magnesium olivine and Fe-bearing silicate. Rare earth oxides in the cover flux exist mainly as rare earth silicates. When the content of rare earth oxides reaches a certain value,rare earth oxides precipitate in molten cover flux. It means that the solubility of rare earth oxides is limited. Rare earth oxides may be partly substituted for CaO to form rare earth-silicate which may increase with the basicity reducing.展开更多
Monolithic stoppers play a very important role in continuous casting（ short for CC）. Sometimes,the stopper slag line is seriously eroded and broken,CC has to pause. The research shows that there are three main reaso...Monolithic stoppers play a very important role in continuous casting（ short for CC）. Sometimes,the stopper slag line is seriously eroded and broken,CC has to pause. The research shows that there are three main reasons which bring severe erosion of monolithic stopper slag line. Firstly,much Fe_2O_3 and MnO in slag react with carbon（ C） in the stopper,C is gradually eroded and erosion resistance of the stopper greatly weakens. Secondly,F increase in tundish covering flux will quicken erosion of the stopper slag line. Thirdly, High LOI of tundish covering flux also makes erosion of the stopper slag line speed up. On one hand,CaCO_3 in tundish covering flux decomposes and brings CO_2; on the other hand,minerals with water in tundish covering flux decompose at high temperatures and bring water vapor.Then CO_2 and water vapor react with C in the stopper,C is gradually eroded,aggravating the erosion.展开更多
The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified...The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.展开更多
文摘Lithofacies structure of commercial cover flux and experimental slags were analyzed,and states of rare earth oxides in cover flux were studied. The results show that under the experiment conditions,the mineral structures of original slags are mainly the calcium feldspar,a lot of magnesium olivine and Fe-bearing silicate. Rare earth oxides in the cover flux exist mainly as rare earth silicates. When the content of rare earth oxides reaches a certain value,rare earth oxides precipitate in molten cover flux. It means that the solubility of rare earth oxides is limited. Rare earth oxides may be partly substituted for CaO to form rare earth-silicate which may increase with the basicity reducing.
文摘Monolithic stoppers play a very important role in continuous casting（ short for CC）. Sometimes,the stopper slag line is seriously eroded and broken,CC has to pause. The research shows that there are three main reasons which bring severe erosion of monolithic stopper slag line. Firstly,much Fe_2O_3 and MnO in slag react with carbon（ C） in the stopper,C is gradually eroded and erosion resistance of the stopper greatly weakens. Secondly,F increase in tundish covering flux will quicken erosion of the stopper slag line. Thirdly, High LOI of tundish covering flux also makes erosion of the stopper slag line speed up. On one hand,CaCO_3 in tundish covering flux decomposes and brings CO_2; on the other hand,minerals with water in tundish covering flux decompose at high temperatures and bring water vapor.Then CO_2 and water vapor react with C in the stopper,C is gradually eroded,aggravating the erosion.
基金Item Sponsored by National Natural Science Foundation of China(50904017)
文摘The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.
