To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake grap...To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake graphite as raw materials,with NaCl and NaF mixed salt serving as the medium.The flake graphite was gradually replaced by ZrC modified graphite in the preparation of Al_(2)O_(3)-C refractories,and its impact on the material’s structure and properties was investigated.The results indicate that,compared to samples with only flake graphite,the introduction of 1 mass%to 5 mass%nano-crystalline ZrC modified graphite can significantly enhance the mechanical performance of low-carbon Al_(2)O_(3)-C refractories.When 5 mass%ZrC modified graphite is added,the mechanical properties of the samples are optimal,with the cold modulus of rupture and elastic modulus reaching 22.5 MPa and 65.0 GPa,respectively.展开更多
To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green ...To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.展开更多
Simulative study on corrosion of Al_2O_3-C refractories by mold cover flux has been carried out by means of immersion method.The results show that there fractory exhibits best resistance to the flux corrosion while th...Simulative study on corrosion of Al_2O_3-C refractories by mold cover flux has been carried out by means of immersion method.The results show that there fractory exhibits best resistance to the flux corrosion while the ratio of additive Al and Si is approximately equal to one.In addi- tion,ZrO_2-C specimens exhibit better corrosion resistance to mold cover.flux than Al_2O_3-C specimens.展开更多
Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production costs.To explore the relationshi...Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production costs.To explore the relationship between refractory composition and interface interaction,unprotected coated Al_(2)O_(3)–MgO refractories and SiO2-coated Al_(2)O_(3)–MgO refractories were added to rare earth high-carbon heavy rail steel under laboratory conditions,and the Al_(2)O_(3)–MgO refractory was found to be more suitable.The results show that,from the epoxy resin side to the refractory side,the contour of the refractory interface reaction layer can be divided into two main layers:an iron-rich reaction layer and an iron-poor reaction layer.Calculations based on the spherical model suggest that the adhesion force is proportional to the size of the refractory particles and inclusions,and the same result applies to the surface tension.Controlling the inclusions at a smaller size has a specific effect on alleviating the erosion of refractories.Combined with the erosion mechanism of Al_(2)O_(3)–MgO refractories,the interface reaction mechanism between Al_(2)O_(3)–MgO refractories and molten steel was proposed,which provides ideas for solving SEN clogging.展开更多
To improve the properties of low-carbonization of MgO–C refractories,the introduction of composite additives is an effective strategy.Al_(2)O_(3)–SiC composite powder was prepared from clay using electromagnetic ind...To improve the properties of low-carbonization of MgO–C refractories,the introduction of composite additives is an effective strategy.Al_(2)O_(3)–SiC composite powder was prepared from clay using electromagnetic induction heating and carbon embedded methods.Further,the Al_(2)O_(3)–SiC composite powder synthesized by electromagnetic induction heating at 600 A was added into low-carbon MgO–C refractories(4 wt.%)to improve their properties.The results showed that when the addition amount of Al_(2)O_(3)–SiC composite powder is within the range of 2.5–5.0 wt.%,the properties of low-carbon MgO–C samples were significantly improved,e.g.,the apparent porosity of 7.58%–8.04%,the bulk density of 2.98–2.99 g cm-3,the cold compressive strength of 55.72–57.93 MPa,the residual strength after three air quenching at 1100°C of 74.86%–78.04%,and the decarburized layer depth after oxidized at 1400°C for 2 h of 14.03–14.87 mm.Consequently,the idea for the rapid synthesis of Al_(2)O_(3)–SiC composite powder provides an alternative low-carbon MgO–C refractories performance optimization strategy.展开更多
h-BN can be applied in Al_(2)O_(3)–C refractories to substitute graphite due to their similar crystal structure and better resistance to molten steel and oxidation.The effects of h-BN particle size on the mechanical ...h-BN can be applied in Al_(2)O_(3)–C refractories to substitute graphite due to their similar crystal structure and better resistance to molten steel and oxidation.The effects of h-BN particle size on the mechanical properties and fracture behavior of Al_(2)O_(3)–C refractories were investigated through wedge splitting test and microstructural analyses.The obtained results demonstrated that the addition of larger-sized h-BN was conducive to the growth of in situ formed SiC whiskers,which contributed to the highest flexural strength(42.63±3.10 MPa)of specimen D10.In comparison,the smaller-sized h-BN can induce more crack propagation paths along the interface and within matrix,leading to more tortuous crack propagation paths,and thus the thermal shock-related parameters such as specific fracture energy,characteristic length,and thermal shock resistance were improved.Consequently,the residual strength ratio of Al_(2)O_(3)–C refractories was increased from 35.5%to 42.5%with decreasing the h-BN particle size from 10 to 0.1μm.展开更多
Al_(2)O_(3)-and MgO-based oxides are among the most common oxides in the steelmaking industry.They exist as the main components of refractories,inclusions,or slags.Al_(2)O_(3)-and MgO-based oxides interact with molten...Al_(2)O_(3)-and MgO-based oxides are among the most common oxides in the steelmaking industry.They exist as the main components of refractories,inclusions,or slags.Al_(2)O_(3)-and MgO-based oxides interact with molten slags continuously during the steel smelting process,which may lead to the dissolution and absorption of the oxides by molten slags,or reactions between oxides and molten slags to form intermediate products.Understanding the dissolution behavior of Al_(2)O_(3)-and MgO-based oxides in molten slags is important for prolonging the service life of refractories and removing inclusions in molten steel.Therefore,Al_(2)O_(3)-and MgO-based oxides are considered,and the test methods,dissolution mechanisms,and influencing factors are comprehensively introduced,which can provide a foundation for refractories wear and high-quality steel smelting.展开更多
文摘To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake graphite as raw materials,with NaCl and NaF mixed salt serving as the medium.The flake graphite was gradually replaced by ZrC modified graphite in the preparation of Al_(2)O_(3)-C refractories,and its impact on the material’s structure and properties was investigated.The results indicate that,compared to samples with only flake graphite,the introduction of 1 mass%to 5 mass%nano-crystalline ZrC modified graphite can significantly enhance the mechanical performance of low-carbon Al_(2)O_(3)-C refractories.When 5 mass%ZrC modified graphite is added,the mechanical properties of the samples are optimal,with the cold modulus of rupture and elastic modulus reaching 22.5 MPa and 65.0 GPa,respectively.
基金This work was supported by the National Natural Science Foundation of China(5180021223)Henan Provice Science&Technology Programs(232102231046 and 232102231051)Cultivation Programme for Yong Backbone Teachers in Henan University to Technology(2142121).
文摘To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.
文摘Simulative study on corrosion of Al_2O_3-C refractories by mold cover flux has been carried out by means of immersion method.The results show that there fractory exhibits best resistance to the flux corrosion while the ratio of additive Al and Si is approximately equal to one.In addi- tion,ZrO_2-C specimens exhibit better corrosion resistance to mold cover.flux than Al_2O_3-C specimens.
基金the State Key Laboratory of Rare Earth Resources Research and Comprehensive Utilization of Baiyun Obo for the open project(Grant No.2022(Kehe)00281)the Central Government Guidance Local Science and Technology Development Fund Project(Grant No.2022ZY0124)for supporting this worksupported by the National Natural Science Foundation of China(Grant No.52074179).
文摘Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production costs.To explore the relationship between refractory composition and interface interaction,unprotected coated Al_(2)O_(3)–MgO refractories and SiO2-coated Al_(2)O_(3)–MgO refractories were added to rare earth high-carbon heavy rail steel under laboratory conditions,and the Al_(2)O_(3)–MgO refractory was found to be more suitable.The results show that,from the epoxy resin side to the refractory side,the contour of the refractory interface reaction layer can be divided into two main layers:an iron-rich reaction layer and an iron-poor reaction layer.Calculations based on the spherical model suggest that the adhesion force is proportional to the size of the refractory particles and inclusions,and the same result applies to the surface tension.Controlling the inclusions at a smaller size has a specific effect on alleviating the erosion of refractories.Combined with the erosion mechanism of Al_(2)O_(3)–MgO refractories,the interface reaction mechanism between Al_(2)O_(3)–MgO refractories and molten steel was proposed,which provides ideas for solving SEN clogging.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.U20A20239 and U1908227)the Fundamental Research Funds for the Central Universities(Grant No.N2125002)the open research fund for State Key Laboratory of Advance Refractories(Grant No.SKLAR202001).
文摘To improve the properties of low-carbonization of MgO–C refractories,the introduction of composite additives is an effective strategy.Al_(2)O_(3)–SiC composite powder was prepared from clay using electromagnetic induction heating and carbon embedded methods.Further,the Al_(2)O_(3)–SiC composite powder synthesized by electromagnetic induction heating at 600 A was added into low-carbon MgO–C refractories(4 wt.%)to improve their properties.The results showed that when the addition amount of Al_(2)O_(3)–SiC composite powder is within the range of 2.5–5.0 wt.%,the properties of low-carbon MgO–C samples were significantly improved,e.g.,the apparent porosity of 7.58%–8.04%,the bulk density of 2.98–2.99 g cm-3,the cold compressive strength of 55.72–57.93 MPa,the residual strength after three air quenching at 1100°C of 74.86%–78.04%,and the decarburized layer depth after oxidized at 1400°C for 2 h of 14.03–14.87 mm.Consequently,the idea for the rapid synthesis of Al_(2)O_(3)–SiC composite powder provides an alternative low-carbon MgO–C refractories performance optimization strategy.
基金This work was supported financially by the National Natural Science Foundation of China(NSFC,Grant Nos.51872211 and 51702065)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(2019ZYYD003 and 2019ZYYD076).
文摘h-BN can be applied in Al_(2)O_(3)–C refractories to substitute graphite due to their similar crystal structure and better resistance to molten steel and oxidation.The effects of h-BN particle size on the mechanical properties and fracture behavior of Al_(2)O_(3)–C refractories were investigated through wedge splitting test and microstructural analyses.The obtained results demonstrated that the addition of larger-sized h-BN was conducive to the growth of in situ formed SiC whiskers,which contributed to the highest flexural strength(42.63±3.10 MPa)of specimen D10.In comparison,the smaller-sized h-BN can induce more crack propagation paths along the interface and within matrix,leading to more tortuous crack propagation paths,and thus the thermal shock-related parameters such as specific fracture energy,characteristic length,and thermal shock resistance were improved.Consequently,the residual strength ratio of Al_(2)O_(3)–C refractories was increased from 35.5%to 42.5%with decreasing the h-BN particle size from 10 to 0.1μm.
基金financially supported by the National Natural Science Foundation of China(U1908227,U1860205,and U21A2057)Key Program of Natural Science Foundation of Hubei Province(2021CFA071)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(20I9ZYYD076).
文摘Al_(2)O_(3)-and MgO-based oxides are among the most common oxides in the steelmaking industry.They exist as the main components of refractories,inclusions,or slags.Al_(2)O_(3)-and MgO-based oxides interact with molten slags continuously during the steel smelting process,which may lead to the dissolution and absorption of the oxides by molten slags,or reactions between oxides and molten slags to form intermediate products.Understanding the dissolution behavior of Al_(2)O_(3)-and MgO-based oxides in molten slags is important for prolonging the service life of refractories and removing inclusions in molten steel.Therefore,Al_(2)O_(3)-and MgO-based oxides are considered,and the test methods,dissolution mechanisms,and influencing factors are comprehensively introduced,which can provide a foundation for refractories wear and high-quality steel smelting.
