The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface react...The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve conditions for continuous casting, a new mould flux based on aluminate system was devised. The viscous properties were investigated. Scanning electron microscopy and X-ray diffraction were applied to detect and characterize the crystalline phases in the continuous cooling process. The results showed that appropriate addition of CeOcould avoid the precipitation of CaO and decrease the viscosity of the mould flux. Increasing the mass ratio of CaO /AlO, especially to a value exceeding 1, could worsen the stability of the mould flux. With a content of less than 14 wt.%, LiO could reduce the viscosity and breaking temperature, but its effect could be weakened for the promoted precipitation of LiAlO. To obtain a mould flux with stable viscous properties, such as viscosity and breaking temperature, appropriate contents of CeOand LiO should be controlled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO /AlOshould not be more than 1.展开更多
In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film,free-fluoride mould flux with various La2O3 content were investigated by using sel...In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film,free-fluoride mould flux with various La2O3 content were investigated by using self-made mould simulator,comprehensive thermal analyzer and SEM-EDS.With the increase of La2O3 content from 0% to 20%,the crystallization ratios of mould flux films were improved from 2% to 90% and the thicknesses of films were also enhanced over two times.Moreover,crystallization temperature was greatly raised and its increasing extent reached 100 oC.It could also decrease the melting temperature of casting powder about 50 oC.However,the undissolved La2O3 particles appeared in slag film if the ratio of La2O3 in free-fluoride mould flux was much too high.展开更多
The thermal conductivity of the mould fluxes containing transition metal oxides was measured by hotline method at different temperatures. The relationship between the thermal conductivity of mold fluxes and the conten...The thermal conductivity of the mould fluxes containing transition metal oxides was measured by hotline method at different temperatures. The relationship between the thermal conductivity of mold fluxes and the contents of transition metal oxides was discussed. The synthetic slags were composed of 30.0% - 35.4%CaO, 34.7% - 38.6% SiO2, 6% Al2O3, 9% Na2O, 14.4% CaF2, 0-4% Cr2O3 and 0-8% MnO in mass percent. The results indicated that Cr2O3 and MnO had a negative effect on thermal conductivity of mold fluxes. The thermal conductivity of mold fluxes was about 0.25-0.55 W/（m · K） when the temperature reached 1 300 ℃, and it increased sharply to about 1.32-1.99 W/（m · K） when the temperature reduced from 1300 to 1000 ℃. The thermal conductivity of mold fluxes containing Cr2 O3 and MnO was 10 %- 25% lower than those of original fluxes. The decrease in thermal conductivity was attributed to the change of molecular structure of mold fluxes. In addition, the poor integrity and regulation of polycrystal structure, complexity of crystal structure, and effects of impurities in the boundary and lat- tice distortion leaded to the reduction in the thermal conductivity. Na2 CrO4, Mn2 SiO4 and other minor phases were also found in the samples containing Cr2O3 and MnO, respectively.展开更多
基金supported by the National Natural Science Foundation of China(51374059,51304042)the Fundamental Research Funds for the Central Universities of China(N130402020)the Key Science and Technology Program of Liaoning Province(2012221013)
文摘The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve conditions for continuous casting, a new mould flux based on aluminate system was devised. The viscous properties were investigated. Scanning electron microscopy and X-ray diffraction were applied to detect and characterize the crystalline phases in the continuous cooling process. The results showed that appropriate addition of CeOcould avoid the precipitation of CaO and decrease the viscosity of the mould flux. Increasing the mass ratio of CaO /AlO, especially to a value exceeding 1, could worsen the stability of the mould flux. With a content of less than 14 wt.%, LiO could reduce the viscosity and breaking temperature, but its effect could be weakened for the promoted precipitation of LiAlO. To obtain a mould flux with stable viscous properties, such as viscosity and breaking temperature, appropriate contents of CeOand LiO should be controlled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO /AlOshould not be more than 1.
基金Project supported by the Inner Mongolia Science Foundation of China (20080404MS)
文摘In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film,free-fluoride mould flux with various La2O3 content were investigated by using self-made mould simulator,comprehensive thermal analyzer and SEM-EDS.With the increase of La2O3 content from 0% to 20%,the crystallization ratios of mould flux films were improved from 2% to 90% and the thicknesses of films were also enhanced over two times.Moreover,crystallization temperature was greatly raised and its increasing extent reached 100 oC.It could also decrease the melting temperature of casting powder about 50 oC.However,the undissolved La2O3 particles appeared in slag film if the ratio of La2O3 in free-fluoride mould flux was much too high.
基金Sponsored by Doctor Programs Foundation of Education Ministry of China(200806110006)
文摘The thermal conductivity of the mould fluxes containing transition metal oxides was measured by hotline method at different temperatures. The relationship between the thermal conductivity of mold fluxes and the contents of transition metal oxides was discussed. The synthetic slags were composed of 30.0% - 35.4%CaO, 34.7% - 38.6% SiO2, 6% Al2O3, 9% Na2O, 14.4% CaF2, 0-4% Cr2O3 and 0-8% MnO in mass percent. The results indicated that Cr2O3 and MnO had a negative effect on thermal conductivity of mold fluxes. The thermal conductivity of mold fluxes was about 0.25-0.55 W/（m · K） when the temperature reached 1 300 ℃, and it increased sharply to about 1.32-1.99 W/（m · K） when the temperature reduced from 1300 to 1000 ℃. The thermal conductivity of mold fluxes containing Cr2 O3 and MnO was 10 %- 25% lower than those of original fluxes. The decrease in thermal conductivity was attributed to the change of molecular structure of mold fluxes. In addition, the poor integrity and regulation of polycrystal structure, complexity of crystal structure, and effects of impurities in the boundary and lat- tice distortion leaded to the reduction in the thermal conductivity. Na2 CrO4, Mn2 SiO4 and other minor phases were also found in the samples containing Cr2O3 and MnO, respectively.
