The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerge...The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.展开更多
为解决路基加固工程中传统胶凝材料造价高、生产过程排碳量高的问题,并实现工业固废资源化和高值化利用,以氢氧化钠作为碱激发剂,制备粉煤灰-矿渣-赤泥三元复合胶凝材料,通过无侧限抗压强度(UCS)试验,研究固废基胶凝材料配合比和氢氧化...为解决路基加固工程中传统胶凝材料造价高、生产过程排碳量高的问题,并实现工业固废资源化和高值化利用,以氢氧化钠作为碱激发剂,制备粉煤灰-矿渣-赤泥三元复合胶凝材料,通过无侧限抗压强度(UCS)试验,研究固废基胶凝材料配合比和氢氧化钠掺量对固化土7 d UCS的影响,并利用SPSS软件对UCS结果进行相关性分析,结合SEM-EDS和XRD手段探讨固废基胶凝材料对土体的固化作用机理。结果表明:不同配合比的固化土试样呈现出劈裂破坏、剪切破坏及拉剪复合破坏三种类型;固废基原材料和碱激发剂间的交互作用对固化土UCS有显著影响,当粉煤灰、矿渣、赤泥质量比为1∶3∶1时,固化土7 d UCS最高,可达1.795 MPa;氢氧化钠掺量与UCS之间存在显著的正相关性,相关系数达到0.76;随着固化土内部水化反应的进行,大量生成的水化硅酸钙、水化铝酸钙凝胶相包裹土颗粒并填充颗粒间孔隙,从而显著提升固化土的强度;随着氢氧化钠掺量的增加,其对水化反应的促进作用更为显著,固化土内部微孔和小孔之和的占比逐渐增加,中孔和大孔之和的占比则逐渐降低。展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52204345 and 52474361)the Scientific Research Innovation Projects of Graduate Student of Jiangsu province,China(No.KYCX24_4184)。
文摘The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.
文摘为解决路基加固工程中传统胶凝材料造价高、生产过程排碳量高的问题,并实现工业固废资源化和高值化利用,以氢氧化钠作为碱激发剂,制备粉煤灰-矿渣-赤泥三元复合胶凝材料,通过无侧限抗压强度(UCS)试验,研究固废基胶凝材料配合比和氢氧化钠掺量对固化土7 d UCS的影响,并利用SPSS软件对UCS结果进行相关性分析,结合SEM-EDS和XRD手段探讨固废基胶凝材料对土体的固化作用机理。结果表明:不同配合比的固化土试样呈现出劈裂破坏、剪切破坏及拉剪复合破坏三种类型;固废基原材料和碱激发剂间的交互作用对固化土UCS有显著影响,当粉煤灰、矿渣、赤泥质量比为1∶3∶1时,固化土7 d UCS最高,可达1.795 MPa;氢氧化钠掺量与UCS之间存在显著的正相关性,相关系数达到0.76;随着固化土内部水化反应的进行,大量生成的水化硅酸钙、水化铝酸钙凝胶相包裹土颗粒并填充颗粒间孔隙,从而显著提升固化土的强度;随着氢氧化钠掺量的增加,其对水化反应的促进作用更为显著,固化土内部微孔和小孔之和的占比逐渐增加,中孔和大孔之和的占比则逐渐降低。
