Al_(4)SiC_(4) was synthesized from Al powder, silicon carbide, and graphite by microwave sintering, and characterized by XRD and SEM. Then the synthesized material was added to the magnesia carbon refractory brick to ...Al_(4)SiC_(4) was synthesized from Al powder, silicon carbide, and graphite by microwave sintering, and characterized by XRD and SEM. Then the synthesized material was added to the magnesia carbon refractory brick to study its effect on the oxidation resistance, apparent porosity, bulk density, elastic modulus, and modulus of rupture. It is found that Al_(4)SiC_(4) can be synthesized by microwave sintering at 1 300 ℃ and the addition of Al_(4)SiC_(4)-containing material as an antioxidant can enhance the oxidation resistance of the magnesia carbon refractory brick.展开更多
Due to thermal stability and excellent resistance to slag erosion,the used refractories can be recycled as the main raw material for some refractories.In this article the latest developments about used refractories in...Due to thermal stability and excellent resistance to slag erosion,the used refractories can be recycled as the main raw material for some refractories.In this article the latest developments about used refractories in metallurgical industry has been reviewed,focusing on the results reported in the past decade.The research and reutilization methods of used refractories were discussed.For the research of used refractories,the results of two aspects,the performance and surface corrosion characteristics,are summarized.Then,the advances in research on recycling technology of several main kinds of used refractories,such as MgO-C,Al2O3-SiC-C,Al2O3-MgO-C,magnesium-chrome,and corundum-spinel refractories were summarized and discussed in detail.Some results of the author’s group were reported等线accompanied by these comments.The microstructure and chemical composition were studied by scanning electron microscopy and energy dispersion spectra,and the properties of the refractories were analyzed.Afterwards,the scope of application of materials was determined according to the classification and analysis of refractories.Finally,the large-scale application of used refractories and an outlook is given to future developments of the entire recycling industry.展开更多
The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, A...The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, Al2O3-SiC-C castable and MgO-Cr2O3 bricks. Recycled refractories exhibit the same or even better properties as compared with the original. In addition, prospects for recycle of used refractories are also discusseded.展开更多
Wetting phenomena between MgO C and CaO SiO2 slags were investigated by varying carbon content.A sessile drop technique was adopted to study the wetting phenomena in conjunction with a high speed camera for the observ...Wetting phenomena between MgO C and CaO SiO2 slags were investigated by varying carbon content.A sessile drop technique was adopted to study the wetting phenomena in conjunction with a high speed camera for the observation of intrinsic wetting phenomena.The results show that the high content of SiO2 and the presence of Al2O3 in slags enhance the diffusion of Mg2+,leading to the promotion of reactive wetting.The carbon in MgO C refractory impedes the penetration of slags by repelling the slag and slowing the diffusion of Mg2+.This accounts for the non-wetting behavior of the slag on MgO C refractory with 17% (mass fraction) carbon similar to that of graphite.展开更多
In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and l...In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and length of the fibers increased with rising temperature. Ferrocene may have catalytic effects on the growth of the fibers in two aspects. First, the reaction between MgO and C and the decomposition of Al4C3 may be catalyzed at high temperature. Suitable concentration gaseous phase is then created for vapor-vapor reaction which could result in the in-situ formation of fibers. Second, Fe nanoparticle produced from ferrocene can act as catalytic droplets and catalyze the growth of the fibers. The fibers are formed via the vapor-liquid-solid and vapor-solid mechanisms. In terms of chemical thermodynamics, the partial pressure of CO and Mg（g） are found to play an important role in the in-situ fibers formation. Different concentration of vapors affects the size, amount and composition of the fibers at different temperatures. The mechanical properties of MgO-C brick was found to be improved by ferrocene addition.展开更多
The interaction between the slag containing titanium oxides(TiO2of 2.0 %-20.0%)and a MgO-C based refractory was investigated by immersion test.The relationship between TiO2 content in slag and corrosion rate of the re...The interaction between the slag containing titanium oxides(TiO2of 2.0 %-20.0%)and a MgO-C based refractory was investigated by immersion test.The relationship between TiO2 content in slag and corrosion rate of the refractory was studied.The microstructure and compositions of the corroded refractory were analyzed by SEM and X-ray diffraction.The corrosion mechanism of MgO-C based refractory in the slag containing titanium was proposed,and the effects of TiO2 content,slag basicity(ωCaO/ωSiO2)and temperature in molten bath on the corrosion rate of the refractory were obtained.展开更多
The development of efficient bonding agents is one aspect of the advancement of refractories. Based on a newly developed binder system, a new generation of tarresin bonded magnesia carbon products with high performanc...The development of efficient bonding agents is one aspect of the advancement of refractories. Based on a newly developed binder system, a new generation of tarresin bonded magnesia carbon products with high performance has been developed. Furthermore, the binder system characterized by high carbon yield after carbonization results in forming an extremely strong carbon bonding. It can improve refractories properties to get new product with more advantages than old refractories： more economic, lower cost and low toxicity. Tar-resin is not only used in shaped refractories, but also in more refractories types, such as monolithic refractories. Immersion experiments of MgO- C monolithic refractories samples in liquid steel at 1600℃ have been carried out for steel making industry. These experiments showed the formation of a dense and continuous MgO rich layer, on the interface between refractory and steel, and the possible formation of inclusions as large clusters protruding from the refractory surface. For the mechanical properties, the powder was heated up to 1400℃ in air to remove carbon, and was subsequently formed into brick shape. Standard ASTM was used to determine the MOR, porosity and density. It is found that antioxidantmaterials play an important role in improving the mechanical properties.展开更多
The effect of Al content in molten steel on the interaction between SPHC steel(0.005-0.068 wt.%Al,and 19×10^(-4)-58×10^(-4)wt.%O)and MgO-C refractory(11.63 wt.%C)was investigated.Non-metallic inclusions in t...The effect of Al content in molten steel on the interaction between SPHC steel(0.005-0.068 wt.%Al,and 19×10^(-4)-58×10^(-4)wt.%O)and MgO-C refractory(11.63 wt.%C)was investigated.Non-metallic inclusions in the steel were examined at various periods(0,5,15,30,45,and 60 min)as well as the MgO-C interface after 60 min of corrosion at 1600℃.The results show that when MgO-C refractory comes into contact with SPHC steel,the refractory interface consists of three layers arranged from the innermost to the outermost,including the original refractory layer,the dense MgO layer,and the iron infiltration layer.The carbon in the MgO-C refractories and the Al content in the molten steel undergo a reaction with the MgO in the refractories,resulting in an increase in Mg concentration in the steel.Increasing Al content in the molten steel from 0.005 to 0.068 wt.%causes a spinel layer to appear at the interface,and the disappearance time of Al_(2)O_(3) inclusions in the steel decreases from 60 to 30 min,while the average MgO content in inclusions increases.Therefore,controlling the Al content in the molten steel and the smelting duration can help regulate the formation of spinel inclusionsinthe steel.展开更多
To solve the problem of poor high-temperature service performance caused by low carbonization of MgO-C refractories,low-carbon MgO–C refractories with excellent thermal shock,oxidation and corrosion resistances were ...To solve the problem of poor high-temperature service performance caused by low carbonization of MgO-C refractories,low-carbon MgO–C refractories with excellent thermal shock,oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al_(2)O_(3) powders as additives.The results indicated that the addition of micro-Al_(2)O_(3) powders optimized the internal structure of the material,like the columnar β-Si_(3)N_(4) with a stepped distribution and the mosaic structure formed between granular and flaky Mg_(2)SiO_(4),which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance.Specifically,the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa,respectively.Moreover,the addition of micro-Al_(2)O_(3) powders promoted the formation of fine particles of Mg_(2)SiO_(4),MgAl_(2)O_(4) and MgO,as well as a dense protective layer of Mg_(2)SiO_(4) in the material under high-temperature environment.Furthermore,spinel and high-temperature solid solution were formed in the corrosion environment.The oxidation and corrosion resistances were greatly improved by 41%and 15%,respectively.展开更多
It has been reported that a 92-year-old female had got a bruise superficial wound on her right leg one and a half years ago,developing into refractory skin ulcer due to improper management before.A prepared cream,mixe...It has been reported that a 92-year-old female had got a bruise superficial wound on her right leg one and a half years ago,developing into refractory skin ulcer due to improper management before.A prepared cream,mixed royal jelly with berberine for dressing change,was made on the scene through the crush of berberine tablets,working with fresh royal jelly.Topical dressing change with the cream was done every 3 days,and two months later,such the ulcer became clean and was covered fully with fresh granulation tissue.This kind of cream consists of the ingredients of TCM purely,free of antibiotic,and being quite effective clinically,also helpful for proper use of antibiotic.展开更多
MgO-C refractories with stainless steel fibers were prepared to investigate the effects of stainless steel fibers addition on the thermal shock resistance,oxidation resistance,and microstructure of MgO-C refractories,...MgO-C refractories with stainless steel fibers were prepared to investigate the effects of stainless steel fibers addition on the thermal shock resistance,oxidation resistance,and microstructure of MgO-C refractories,and the optimum amount of stainless steel fibers was determined.The results showed that adding stainless steel fiber in MgO-C refractories can increase flexural strength and thermal shock resistance,with an optimal addition of 2 wt.%,owing to the bridging effect and crack deflection toughening of stainless steel fibers inside the material.The formation of MgAl1.9Fe0.1O4 composite spinel,which was responsible for higher oxidation resistance,produced volume expansion and prevented the diffusion of oxygen.The strengthening mechanism is physical embedding at room temperature,while it is reaction bonding at high temperature.展开更多
基金This work was funded by Luoyang Major Science and Technology Innovation Project(2301009A)Henan Province Key Research and Development Project(231111230200)。
文摘Al_(4)SiC_(4) was synthesized from Al powder, silicon carbide, and graphite by microwave sintering, and characterized by XRD and SEM. Then the synthesized material was added to the magnesia carbon refractory brick to study its effect on the oxidation resistance, apparent porosity, bulk density, elastic modulus, and modulus of rupture. It is found that Al_(4)SiC_(4) can be synthesized by microwave sintering at 1 300 ℃ and the addition of Al_(4)SiC_(4)-containing material as an antioxidant can enhance the oxidation resistance of the magnesia carbon refractory brick.
基金National Key R&D Program of China(Grant No.2018YFC1901504)National Natural Science Foundation of China(Grant No.51872268).
文摘Due to thermal stability and excellent resistance to slag erosion,the used refractories can be recycled as the main raw material for some refractories.In this article the latest developments about used refractories in metallurgical industry has been reviewed,focusing on the results reported in the past decade.The research and reutilization methods of used refractories were discussed.For the research of used refractories,the results of two aspects,the performance and surface corrosion characteristics,are summarized.Then,the advances in research on recycling technology of several main kinds of used refractories,such as MgO-C,Al2O3-SiC-C,Al2O3-MgO-C,magnesium-chrome,and corundum-spinel refractories were summarized and discussed in detail.Some results of the author’s group were reported等线accompanied by these comments.The microstructure and chemical composition were studied by scanning electron microscopy and energy dispersion spectra,and the properties of the refractories were analyzed.Afterwards,the scope of application of materials was determined according to the classification and analysis of refractories.Finally,the large-scale application of used refractories and an outlook is given to future developments of the entire recycling industry.
文摘The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, Al2O3-SiC-C castable and MgO-Cr2O3 bricks. Recycled refractories exhibit the same or even better properties as compared with the original. In addition, prospects for recycle of used refractories are also discusseded.
基金supported by the R&D Center for Valuable Recycling(Global-Top Environmental Technology Development Program)funded by the Ministry of Environment(Project No.:11-C22-ID)
文摘Wetting phenomena between MgO C and CaO SiO2 slags were investigated by varying carbon content.A sessile drop technique was adopted to study the wetting phenomena in conjunction with a high speed camera for the observation of intrinsic wetting phenomena.The results show that the high content of SiO2 and the presence of Al2O3 in slags enhance the diffusion of Mg2+,leading to the promotion of reactive wetting.The carbon in MgO C refractory impedes the penetration of slags by repelling the slag and slowing the diffusion of Mg2+.This accounts for the non-wetting behavior of the slag on MgO C refractory with 17% (mass fraction) carbon similar to that of graphite.
基金Funded by the National Natural Science Foundation of China (No.50872125)
文摘In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and length of the fibers increased with rising temperature. Ferrocene may have catalytic effects on the growth of the fibers in two aspects. First, the reaction between MgO and C and the decomposition of Al4C3 may be catalyzed at high temperature. Suitable concentration gaseous phase is then created for vapor-vapor reaction which could result in the in-situ formation of fibers. Second, Fe nanoparticle produced from ferrocene can act as catalytic droplets and catalyze the growth of the fibers. The fibers are formed via the vapor-liquid-solid and vapor-solid mechanisms. In terms of chemical thermodynamics, the partial pressure of CO and Mg（g） are found to play an important role in the in-situ fibers formation. Different concentration of vapors affects the size, amount and composition of the fibers at different temperatures. The mechanical properties of MgO-C brick was found to be improved by ferrocene addition.
文摘The interaction between the slag containing titanium oxides(TiO2of 2.0 %-20.0%)and a MgO-C based refractory was investigated by immersion test.The relationship between TiO2 content in slag and corrosion rate of the refractory was studied.The microstructure and compositions of the corroded refractory were analyzed by SEM and X-ray diffraction.The corrosion mechanism of MgO-C based refractory in the slag containing titanium was proposed,and the effects of TiO2 content,slag basicity(ωCaO/ωSiO2)and temperature in molten bath on the corrosion rate of the refractory were obtained.
文摘The development of efficient bonding agents is one aspect of the advancement of refractories. Based on a newly developed binder system, a new generation of tarresin bonded magnesia carbon products with high performance has been developed. Furthermore, the binder system characterized by high carbon yield after carbonization results in forming an extremely strong carbon bonding. It can improve refractories properties to get new product with more advantages than old refractories： more economic, lower cost and low toxicity. Tar-resin is not only used in shaped refractories, but also in more refractories types, such as monolithic refractories. Immersion experiments of MgO- C monolithic refractories samples in liquid steel at 1600℃ have been carried out for steel making industry. These experiments showed the formation of a dense and continuous MgO rich layer, on the interface between refractory and steel, and the possible formation of inclusions as large clusters protruding from the refractory surface. For the mechanical properties, the powder was heated up to 1400℃ in air to remove carbon, and was subsequently formed into brick shape. Standard ASTM was used to determine the MOR, porosity and density. It is found that antioxidantmaterials play an important role in improving the mechanical properties.
基金supported by the National Natural Science Foundation of China(51974017).
文摘The effect of Al content in molten steel on the interaction between SPHC steel(0.005-0.068 wt.%Al,and 19×10^(-4)-58×10^(-4)wt.%O)and MgO-C refractory(11.63 wt.%C)was investigated.Non-metallic inclusions in the steel were examined at various periods(0,5,15,30,45,and 60 min)as well as the MgO-C interface after 60 min of corrosion at 1600℃.The results show that when MgO-C refractory comes into contact with SPHC steel,the refractory interface consists of three layers arranged from the innermost to the outermost,including the original refractory layer,the dense MgO layer,and the iron infiltration layer.The carbon in the MgO-C refractories and the Al content in the molten steel undergo a reaction with the MgO in the refractories,resulting in an increase in Mg concentration in the steel.Increasing Al content in the molten steel from 0.005 to 0.068 wt.%causes a spinel layer to appear at the interface,and the disappearance time of Al_(2)O_(3) inclusions in the steel decreases from 60 to 30 min,while the average MgO content in inclusions increases.Therefore,controlling the Al content in the molten steel and the smelting duration can help regulate the formation of spinel inclusionsinthe steel.
基金the Scientific Research Fund of Hunan Provincial Education Department(22B0856)the Hengyang"Xiaohe"Science and Technology Talent Special Project([2023]45)+3 种基金the Guidance Plan Project of Hengyang City([2023]40)the National Natural Science Foundation of China(U20A20239)the College Students'Innovation and Entrepreneurship Training Project(S202311528055)the Characteristic Application Discipline of Material Science Engineering in Hunan Province([2022]351).
文摘To solve the problem of poor high-temperature service performance caused by low carbonization of MgO-C refractories,low-carbon MgO–C refractories with excellent thermal shock,oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al_(2)O_(3) powders as additives.The results indicated that the addition of micro-Al_(2)O_(3) powders optimized the internal structure of the material,like the columnar β-Si_(3)N_(4) with a stepped distribution and the mosaic structure formed between granular and flaky Mg_(2)SiO_(4),which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance.Specifically,the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa,respectively.Moreover,the addition of micro-Al_(2)O_(3) powders promoted the formation of fine particles of Mg_(2)SiO_(4),MgAl_(2)O_(4) and MgO,as well as a dense protective layer of Mg_(2)SiO_(4) in the material under high-temperature environment.Furthermore,spinel and high-temperature solid solution were formed in the corrosion environment.The oxidation and corrosion resistances were greatly improved by 41%and 15%,respectively.
文摘It has been reported that a 92-year-old female had got a bruise superficial wound on her right leg one and a half years ago,developing into refractory skin ulcer due to improper management before.A prepared cream,mixed royal jelly with berberine for dressing change,was made on the scene through the crush of berberine tablets,working with fresh royal jelly.Topical dressing change with the cream was done every 3 days,and two months later,such the ulcer became clean and was covered fully with fresh granulation tissue.This kind of cream consists of the ingredients of TCM purely,free of antibiotic,and being quite effective clinically,also helpful for proper use of antibiotic.
基金supported by the Scientific and Technological Research Project of the Henan Provincial Department of Science and Technology of China(No.212102210579).
文摘MgO-C refractories with stainless steel fibers were prepared to investigate the effects of stainless steel fibers addition on the thermal shock resistance,oxidation resistance,and microstructure of MgO-C refractories,and the optimum amount of stainless steel fibers was determined.The results showed that adding stainless steel fiber in MgO-C refractories can increase flexural strength and thermal shock resistance,with an optimal addition of 2 wt.%,owing to the bridging effect and crack deflection toughening of stainless steel fibers inside the material.The formation of MgAl1.9Fe0.1O4 composite spinel,which was responsible for higher oxidation resistance,produced volume expansion and prevented the diffusion of oxygen.The strengthening mechanism is physical embedding at room temperature,while it is reaction bonding at high temperature.
