The Interfacial phenomena in mold have a great impact on the smooth operation of continuous casting process and the quality of the casting product.In this paper,the wetting behavior of CaO-Al_(2)O_(3)-based mold flux ...The Interfacial phenomena in mold have a great impact on the smooth operation of continuous casting process and the quality of the casting product.In this paper,the wetting behavior of CaO-Al_(2)O_(3)-based mold flux with different BaO and MgO contents was studied.The results showed that the contact angle between molten flux and interstitial free(IF)steel substrate increased from 62.4°to 74.5°with the increase of BaO content from 3 wt%to 7 wt%,while it decreased from 62.4°to 51.3°with the increase of MgO content from 3 wt%to 7 wt%.The interfacial tension also increased from 1630.3 to 1740.8 mN/m when the BaO content increased,but it reduced from 1630.3 to 1539.7 mN/m with the addition of MgO.The changes of contact angle and interfacial tension were mainly due to the fact that the bridging oxygen(O^(0)) at the interface was broken into non-bridging oxygen(O^(-)) and free oxygen(O_(2-)) by MgO.However,more O^(-) and O_(2-) connected into O^(0) when BaO was added,since the charge compensation effect of BaO was so stronger that it offset the effect of providing O_(2-).展开更多
Based on the theory of micro-inhomogeneity of liquid metal,a calculation model is established for the quantitative description of the structural information of metal melts.Only by thermophysical property parameters an...Based on the theory of micro-inhomogeneity of liquid metal,a calculation model is established for the quantitative description of the structural information of metal melts.Only by thermophysical property parameters and basic structural parameters of solid metal,can this model produce the main information of melt structure,including the relative concentration of active atoms,size of atomic clusters and number of short-range order atoms.Based on this model,the main structural information of Al and Ni melts in the not high range above the liquidus is calculated,with results in good agreement with experimental values.Besides,analyzed is the influence of superheating temperature and atomic number on the melt structural information of the first (IA) and second main group (IIA) elements.With temperature increasing,melt structural information regularly changes for both IA and IIA elements.With the atomic number increasing,melt structural information of IA elements changes regularly,for the crystal structures of the IA elements are all of bcc lattice type.However,no notable regular change of melt structural information for IIA elements has been found,mainly because the lattice type of IIA elements is of hcp-fcc-bcc transition.The present work presents an effective way for better understanding metal melt structure and for forecasting the change of the physical property of metal melts.展开更多
The crytallization behavior and melt structure of the CaO-Si0^(2-)B20_(3)-based fluorine-free mold fux were investigated.The results show that the crytallization of the mold fux was first inhibited and then promoted w...The crytallization behavior and melt structure of the CaO-Si0^(2-)B20_(3)-based fluorine-free mold fux were investigated.The results show that the crytallization of the mold fux was first inhibited and then promoted with the increase in Al_(2)0_(3) content from 4 to 12 wt.%.However,it was enhanced by MgO in the range of 2-10 wt.%.The results of Fourier transform infrared spectroscopy and Raman spectroscopy showed that Al_(2)0_(3) worked as a network former in the mold flux melt when its content was in the range of 4-8 wt.%,whereas it worked as the network breaker to provide 0^(2-)when its content was in the range of 8-12 wt.%.In addition,the combined efects from the charge compensation by Mg^(2+)and the network broken by 0^(2-)led to the increase in some typicalT-O-T(AI-O-A1,B-O-B,etc.,)and simpler structural units(Q^(2)(Si),B_^(O-)in the[B0_(2)0^(-)],.etc.)when the MgO content was in the range of 2-6 wt.%.The continuous increase in 0^(2-)provided by the addition of MgO from 6 to 10 wt.%further depolymerized the network of the melt and fnally caused fast crystallizationo.展开更多
The influence of fluorine on the structure of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 continuous-casting-type slag was measured by Raman spectroscopy,and the degree of polymerization of mould flux and the structural behavior of...The influence of fluorine on the structure of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 continuous-casting-type slag was measured by Raman spectroscopy,and the degree of polymerization of mould flux and the structural behavior of F-in the melt were investigated by classifying and quantifying the structural species of F-ions.The results exhibit that the main structural units of Si-O tetrahedra are Q^0,Q^1 and Q^2,and the actual measured number of non-bridging oxygen ions in the[SiO_4]-tetrahedra(denoted by NBO/T)increases from 2.73 to 3.44 with increasing the molar ratio of F to(F+O)(denoted by X_F/X_((F+O)) from 0.06 to 0.19.It means that the degree of polymerization of melt structure decreases with an increase in X_F/X_((F+O)).In addition,most of F-ions were distributed in Si-O tetrahedra and Al-O tetrahedra.With increasing X_F/X_((F+O)),the complex structural units Al-O tetrahedra are gradually replaced by discrete structural units AlF4-because of the breakage of Al-O bonds in Al-O tetrahedra by F-ions,and the SiO(bridging oxygen)bonds of Si-O tetrahedra are broken to form [SiO_nF_(4-n)]-tetrahedra by F-ions coordinating with Si^(4+).展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51874363 and U1760202)the Natural Science Foundation of Hunan Province,China(No.2019JJ40345)the Hunan Scientific Technology projects,China(Nos.2018RS3022 and 2018WK2051)。
文摘The Interfacial phenomena in mold have a great impact on the smooth operation of continuous casting process and the quality of the casting product.In this paper,the wetting behavior of CaO-Al_(2)O_(3)-based mold flux with different BaO and MgO contents was studied.The results showed that the contact angle between molten flux and interstitial free(IF)steel substrate increased from 62.4°to 74.5°with the increase of BaO content from 3 wt%to 7 wt%,while it decreased from 62.4°to 51.3°with the increase of MgO content from 3 wt%to 7 wt%.The interfacial tension also increased from 1630.3 to 1740.8 mN/m when the BaO content increased,but it reduced from 1630.3 to 1539.7 mN/m with the addition of MgO.The changes of contact angle and interfacial tension were mainly due to the fact that the bridging oxygen(O^(0)) at the interface was broken into non-bridging oxygen(O^(-)) and free oxygen(O_(2-)) by MgO.However,more O^(-) and O_(2-) connected into O^(0) when BaO was added,since the charge compensation effect of BaO was so stronger that it offset the effect of providing O_(2-).
基金supported by the National Basic Research Program of China (Grant No. 2007CB613702)International Cooperation Program in Science and Technology (Grant No. 2007DFC50090)
文摘Based on the theory of micro-inhomogeneity of liquid metal,a calculation model is established for the quantitative description of the structural information of metal melts.Only by thermophysical property parameters and basic structural parameters of solid metal,can this model produce the main information of melt structure,including the relative concentration of active atoms,size of atomic clusters and number of short-range order atoms.Based on this model,the main structural information of Al and Ni melts in the not high range above the liquidus is calculated,with results in good agreement with experimental values.Besides,analyzed is the influence of superheating temperature and atomic number on the melt structural information of the first (IA) and second main group (IIA) elements.With temperature increasing,melt structural information regularly changes for both IA and IIA elements.With the atomic number increasing,melt structural information of IA elements changes regularly,for the crystal structures of the IA elements are all of bcc lattice type.However,no notable regular change of melt structural information for IIA elements has been found,mainly because the lattice type of IIA elements is of hcp-fcc-bcc transition.The present work presents an effective way for better understanding metal melt structure and for forecasting the change of the physical property of metal melts.
基金This work was supported by the National Natural Science Foundation of China(51874363,U1760202)Natural Science Foundation of Hunan Province(2019JJ40345)Hunan Scientific Technology Projects(2018RS3022,2018WK2051).
文摘The crytallization behavior and melt structure of the CaO-Si0^(2-)B20_(3)-based fluorine-free mold fux were investigated.The results show that the crytallization of the mold fux was first inhibited and then promoted with the increase in Al_(2)0_(3) content from 4 to 12 wt.%.However,it was enhanced by MgO in the range of 2-10 wt.%.The results of Fourier transform infrared spectroscopy and Raman spectroscopy showed that Al_(2)0_(3) worked as a network former in the mold flux melt when its content was in the range of 4-8 wt.%,whereas it worked as the network breaker to provide 0^(2-)when its content was in the range of 8-12 wt.%.In addition,the combined efects from the charge compensation by Mg^(2+)and the network broken by 0^(2-)led to the increase in some typicalT-O-T(AI-O-A1,B-O-B,etc.,)and simpler structural units(Q^(2)(Si),B_^(O-)in the[B0_(2)0^(-)],.etc.)when the MgO content was in the range of 2-6 wt.%.The continuous increase in 0^(2-)provided by the addition of MgO from 6 to 10 wt.%further depolymerized the network of the melt and fnally caused fast crystallizationo.
基金the National Natural Science Foundation of China for providing financial support(Nos.51374060 and 51374059)
文摘The influence of fluorine on the structure of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 continuous-casting-type slag was measured by Raman spectroscopy,and the degree of polymerization of mould flux and the structural behavior of F-in the melt were investigated by classifying and quantifying the structural species of F-ions.The results exhibit that the main structural units of Si-O tetrahedra are Q^0,Q^1 and Q^2,and the actual measured number of non-bridging oxygen ions in the[SiO_4]-tetrahedra(denoted by NBO/T)increases from 2.73 to 3.44 with increasing the molar ratio of F to(F+O)(denoted by X_F/X_((F+O)) from 0.06 to 0.19.It means that the degree of polymerization of melt structure decreases with an increase in X_F/X_((F+O)).In addition,most of F-ions were distributed in Si-O tetrahedra and Al-O tetrahedra.With increasing X_F/X_((F+O)),the complex structural units Al-O tetrahedra are gradually replaced by discrete structural units AlF4-because of the breakage of Al-O bonds in Al-O tetrahedra by F-ions,and the SiO(bridging oxygen)bonds of Si-O tetrahedra are broken to form [SiO_nF_(4-n)]-tetrahedra by F-ions coordinating with Si^(4+).