The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,sc...The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,scanning electron microscope and differential thermal analyzer.The results show that as the holding temperature decreases,the morphologies of the primary iron-rich phase in matrix change from star-like to polygonal,and the number of the primary phases gradually decreases and disappears at 615°C.Finally,the Chinese script phases with small size,high compact and uniform distribution are obtained.In contrast,the primary iron-rich phases in slag transform into a coarser polygonal shape with lower roundness,and some of them have hollow structures.Furthermore,the area fraction of intermetallics and Fe content in the matrix decrease gradually due to the formation and growth of sludge and subsequent natural sedimentation during melt holding.With the decrease of holding temperature,the main factors hindering the settlement of the primary phases are morphology,size,and density in turn.展开更多
Increasing iron content has been witnessed an essential method to improve the remanence of 2:17-type Sm-Co-Fe-Cu-Zr magnets,however,the inferior squareness factor accompanied with the increased iron content turns into...Increasing iron content has been witnessed an essential method to improve the remanence of 2:17-type Sm-Co-Fe-Cu-Zr magnets,however,the inferior squareness factor accompanied with the increased iron content turns into a neck sticking problem.In this work,the grain boundary optimization induced substantial squareness enhancement from 63.4%to 91.4%,and consequently an excellent maximum energy product of 32.63 MGOe have been achieved in iron-rich Sm-Co-Fe-Cu-Zr magnets via tuning solution process.It is clearly revealed that the grain boundary(GB)phases as well as the micro-twins’density in grain interiors can be controlled and interprets the enhancement mechanism of squareness.展开更多
At the present time in china, the binder used in tungsten carbide composite button is mainly cobalt, which is very expensive. In order to solve the problems, a new type of rare earth and iron-rich diamond-enhanced tun...At the present time in china, the binder used in tungsten carbide composite button is mainly cobalt, which is very expensive. In order to solve the problems, a new type of rare earth and iron-rich diamond-enhanced tungsten carbide with high abrasive resistance and high toughness against impact, which realizes to substitute ferrum for cobalt, has been developed. The key problems in making the button are to improve the mechanical properties of matrix and increase the welding strength between the diamond and the matrix. All these problems have been solved effectively by low temperature activation hot-press sintering, doping rare earth lanthanum in matrix and high sintering pressure. The properties of the button have been determined under laboratory conditions. The test results show that its hardness is more than 90 HRA, its abrasive resistance is 39 times more than that of conventional cemented tungsten carbide, and its toughness against impact is more than 200 J. All these data show the button has very good mechanical properties.展开更多
A study has been carried out on the feasibility of using high iron content wastes,generated during steel making,as a raw material for the production of glass ceramic.The iron-rich wastes were mixed and melted in diffe...A study has been carried out on the feasibility of using high iron content wastes,generated during steel making,as a raw material for the production of glass ceramic.The iron-rich wastes were mixed and melted in different proportions with soda-lime glass cullet and sand.The devitrification of the parent glasses produced from the different mixtures was investigated using differential thermal analysis,X-ray diffraction,and scanning electron microscopy.The mechanical properties of the glass-ceramic were assessed by hardness and indentation fracture toughness measurement.A glass ceramic with mixture of 60 wt pct iron-rich wastes,25 wt pct sand,and 15 wt pct glass cullet exhibited the best combination of properties,namely,hardness 7.9 CPa and fracture toughness 3.75 MPa·m^1/2,for the sake of containing magnetite in marked dendritic morphology.These new hard glass ceramics are candidate materials for wear resistant tiles and paving for heavy industrial floors.展开更多
The characterization of multiple iron-rich phases in high-pressure die-cast AlSi10MnMg alloy was studied.Attention was focused on the formation and fracture behavior of the primary iron-rich phase((P-IMC)_(I))formed i...The characterization of multiple iron-rich phases in high-pressure die-cast AlSi10MnMg alloy was studied.Attention was focused on the formation and fracture behavior of the primary iron-rich phase((P-IMC)_(I))formed in the shot sleeve and plate-shaped eutectic iron-rich phase in high-pressure die cast(HPDC)AlSi10MnMg alloy.Results show that multiple types of iron-rich phases with various morphologies,in-cluding primary iron-rich phases(polyhedral(P-IMC)_(I) and(P-IMC)_(II))and eutectic iron-rich phases(plate-shaped,net shape,and fish-bone shape),were found in HPDC AlSi10MnMg.Coarse(P-IMC)_(I) formed in the shot sleeve were distributed in the interface between primaryα-Al and binary Al-Si eutectic.Small size(P-IMC)_(II) and various eutectic iron-rich phases formed in the die cavity and they were distributed in Al-Si binary eutectic.The primary iron-rich phases belonged to a simple cubic crystal structure with a lattice constant a=1.265 nm and they exhibited a lateral growth characteristic with a termination of{110}surface.βphase was surrounded byδphase and they coexisted in a plate-shaped iron-rich phase.High-density stacking fault inβphase andδ/βinterface provided an excellent nucleation site forδphase.From mechanical behavior,the stress concentration caused by eutectic iron-rich phases was far less than(P-IMC)_(I) and it would not cause crack initiation along the eutectic cluster boundary.In addition,(P-IMC)_(I) showed the worst deformation coordination with primaryα-Al while the plate-shaped eutectic iron-rich phase exhibited similar deformation characteristics with silicon particles.展开更多
Iron-rich electrolytic manganese residue(IREMR)is an industrial waste produced during the processing of electrolytic metal manganese,and it contains certain amounts of Fe and Mn resources and other heavy metals.In thi...Iron-rich electrolytic manganese residue(IREMR)is an industrial waste produced during the processing of electrolytic metal manganese,and it contains certain amounts of Fe and Mn resources and other heavy metals.In this study,the slurry electrolysis technique was used to recover high-purity Fe powder from IREMR.The effects of IREMR and H2SO4 mass ratio,current density,reaction temper-ature,and electrolytic time on the leaching and current efficiencies of Fe were studied.According to the results,high-purity Fe powder can be recovered from the cathode plate,and the slurry electrolyte can be recycled.The leaching efficiency,current efficiency,and purity of Fe reached 92.58%,80.65%,and 98.72wt%,respectively,at a 1:2.5 mass ratio of H2SO4 and IREMR,reaction temperature of 60℃,electric current density of 30 mA/cm^(2),and reaction time of 8 h.In addition,vibrating sample magnetometer(VSM)analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m,which reached the advanced magnetic grade of electrical pure-iron powder(DT4A coercivity standard).The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER.展开更多
Electromagnetic separation of the iron-rich phase inclusions from Al alloy was investigated. The influencing parameters including magnetic induction density, the section shape of the separating channel and the length ...Electromagnetic separation of the iron-rich phase inclusions from Al alloy was investigated. The influencing parameters including magnetic induction density, the section shape of the separating channel and the length of influential loop of the metal melt on the separation efficiency of iron-rich phase inclusions were studied. The results show that when the proper magnetic induction density (B=0.3T) is applied, rectangle separating channel is used, and the influential loop of the metal melt is long, high separating efficiency of the iron-rich phase inclusions can be obtained.展开更多
A new method has been proposed to prepare Mg-A1-Si master alloys by utilizing scrap AI-Si-Fe alloys with higher Fe levels, which aims to segregate Fe from AI-Si-Fe alloys by Mg melt. The segregation be- haviors, micro...A new method has been proposed to prepare Mg-A1-Si master alloys by utilizing scrap AI-Si-Fe alloys with higher Fe levels, which aims to segregate Fe from AI-Si-Fe alloys by Mg melt. The segregation be- haviors, microstructure morphology and evolution mechanism of iron-rich phases in Mg-A1-Si alloy melts were studied, after AI-14Si-4Fe （wt%） alloys were added and dissolved completely. In the Mg-A1-Si alloys, iron has very little solubility and tends to combine with other elements to form intermetallic phases, which grow into a deposition layer due to the higher density. During the cooling and solidifying process of Mg-A1-Si melts, the needle-like AlsSiFe phase in AI-14Si-4Fe alloy evolved into blocky AI5Fe2 and Al0.7Fe3Si0.3 phases. Besides, the Fe levels of the Mg-AI-Si master alloys were reduced to 0.017 wt% from nominal content of 0.164 wt%. Based on the above results, this work carried out a semi-quantitative phase- compositions analysis for the deposition layer by relative intensity ratio （RIR） method, and evolution mechanism of the iron-rich phases had also been discussed. This study has paved a new way to regen- erate the scrap AI-Si-Fe alloys, which has a great significance of promoting the recycling of aluminum resources.展开更多
The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magne...The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separation indicates that primary needle-like β phases are difficult to separate; while primary α iron-rich phases can be separated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully when the molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.展开更多
Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil a...Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron（III） oxide（from 25 wt% to 50 wt%）, the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy（SEM）, and X-ray diffraction（XRD） was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.展开更多
基金Project(2017GDASCX-0117)supported by the Guangdong Academy of Sciences,ChinaProject(201806010126)supported by the Pearl River S&T Nova Program of Guangzhou,China+3 种基金Projects(2017A050503004,2017A07071029)supported by the Guangdong Provincial Program of Science and Technology,ChinaProject(18126010)supported by the Guangxi Autonomous Regional Program of Science and Technology,ChinaProject(201802030012)supported by the Guangzhou Municipal Science and Technology Bureau,ChinaProject(2017A0109005)supported by the Sihui Plan Project of Science and Technology,China.
文摘The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,scanning electron microscope and differential thermal analyzer.The results show that as the holding temperature decreases,the morphologies of the primary iron-rich phase in matrix change from star-like to polygonal,and the number of the primary phases gradually decreases and disappears at 615°C.Finally,the Chinese script phases with small size,high compact and uniform distribution are obtained.In contrast,the primary iron-rich phases in slag transform into a coarser polygonal shape with lower roundness,and some of them have hollow structures.Furthermore,the area fraction of intermetallics and Fe content in the matrix decrease gradually due to the formation and growth of sludge and subsequent natural sedimentation during melt holding.With the decrease of holding temperature,the main factors hindering the settlement of the primary phases are morphology,size,and density in turn.
基金financially supported by the National Key R&D Program of China(No.2018YFB2003901)NSFC-BRICS(No.51761145026)NSFC(Nos.91960101 and 51520105002)。
文摘Increasing iron content has been witnessed an essential method to improve the remanence of 2:17-type Sm-Co-Fe-Cu-Zr magnets,however,the inferior squareness factor accompanied with the increased iron content turns into a neck sticking problem.In this work,the grain boundary optimization induced substantial squareness enhancement from 63.4%to 91.4%,and consequently an excellent maximum energy product of 32.63 MGOe have been achieved in iron-rich Sm-Co-Fe-Cu-Zr magnets via tuning solution process.It is clearly revealed that the grain boundary(GB)phases as well as the micro-twins’density in grain interiors can be controlled and interprets the enhancement mechanism of squareness.
文摘At the present time in china, the binder used in tungsten carbide composite button is mainly cobalt, which is very expensive. In order to solve the problems, a new type of rare earth and iron-rich diamond-enhanced tungsten carbide with high abrasive resistance and high toughness against impact, which realizes to substitute ferrum for cobalt, has been developed. The key problems in making the button are to improve the mechanical properties of matrix and increase the welding strength between the diamond and the matrix. All these problems have been solved effectively by low temperature activation hot-press sintering, doping rare earth lanthanum in matrix and high sintering pressure. The properties of the button have been determined under laboratory conditions. The test results show that its hardness is more than 90 HRA, its abrasive resistance is 39 times more than that of conventional cemented tungsten carbide, and its toughness against impact is more than 200 J. All these data show the button has very good mechanical properties.
文摘A study has been carried out on the feasibility of using high iron content wastes,generated during steel making,as a raw material for the production of glass ceramic.The iron-rich wastes were mixed and melted in different proportions with soda-lime glass cullet and sand.The devitrification of the parent glasses produced from the different mixtures was investigated using differential thermal analysis,X-ray diffraction,and scanning electron microscopy.The mechanical properties of the glass-ceramic were assessed by hardness and indentation fracture toughness measurement.A glass ceramic with mixture of 60 wt pct iron-rich wastes,25 wt pct sand,and 15 wt pct glass cullet exhibited the best combination of properties,namely,hardness 7.9 CPa and fracture toughness 3.75 MPa·m^1/2,for the sake of containing magnetite in marked dendritic morphology.These new hard glass ceramics are candidate materials for wear resistant tiles and paving for heavy industrial floors.
基金supported by the Major Science and Technology Project of Changchun City,Jilin Province(No.20210301024GX)the National Natural Science Foundation of China(No.52175335)The authors also appreciate the help pro-vided by China FAW Foundry Co.,LTD and Germany ALUMINUM RHEINFELDEN Group.
文摘The characterization of multiple iron-rich phases in high-pressure die-cast AlSi10MnMg alloy was studied.Attention was focused on the formation and fracture behavior of the primary iron-rich phase((P-IMC)_(I))formed in the shot sleeve and plate-shaped eutectic iron-rich phase in high-pressure die cast(HPDC)AlSi10MnMg alloy.Results show that multiple types of iron-rich phases with various morphologies,in-cluding primary iron-rich phases(polyhedral(P-IMC)_(I) and(P-IMC)_(II))and eutectic iron-rich phases(plate-shaped,net shape,and fish-bone shape),were found in HPDC AlSi10MnMg.Coarse(P-IMC)_(I) formed in the shot sleeve were distributed in the interface between primaryα-Al and binary Al-Si eutectic.Small size(P-IMC)_(II) and various eutectic iron-rich phases formed in the die cavity and they were distributed in Al-Si binary eutectic.The primary iron-rich phases belonged to a simple cubic crystal structure with a lattice constant a=1.265 nm and they exhibited a lateral growth characteristic with a termination of{110}surface.βphase was surrounded byδphase and they coexisted in a plate-shaped iron-rich phase.High-density stacking fault inβphase andδ/βinterface provided an excellent nucleation site forδphase.From mechanical behavior,the stress concentration caused by eutectic iron-rich phases was far less than(P-IMC)_(I) and it would not cause crack initiation along the eutectic cluster boundary.In addition,(P-IMC)_(I) showed the worst deformation coordination with primaryα-Al while the plate-shaped eutectic iron-rich phase exhibited similar deformation characteristics with silicon particles.
基金supported by the Key Research and Development Program of Guangxi Province,China (No.AB23075174)the National Natural Science Foundation of China (No.52174386)the Science and Technology Plan Project of Sichuan Province,China (No.2022YFS0459).
文摘Iron-rich electrolytic manganese residue(IREMR)is an industrial waste produced during the processing of electrolytic metal manganese,and it contains certain amounts of Fe and Mn resources and other heavy metals.In this study,the slurry electrolysis technique was used to recover high-purity Fe powder from IREMR.The effects of IREMR and H2SO4 mass ratio,current density,reaction temper-ature,and electrolytic time on the leaching and current efficiencies of Fe were studied.According to the results,high-purity Fe powder can be recovered from the cathode plate,and the slurry electrolyte can be recycled.The leaching efficiency,current efficiency,and purity of Fe reached 92.58%,80.65%,and 98.72wt%,respectively,at a 1:2.5 mass ratio of H2SO4 and IREMR,reaction temperature of 60℃,electric current density of 30 mA/cm^(2),and reaction time of 8 h.In addition,vibrating sample magnetometer(VSM)analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m,which reached the advanced magnetic grade of electrical pure-iron powder(DT4A coercivity standard).The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER.
基金Foundation item: project (59774017) supported by NationalNatureScience Found, China project (G199906490-4) supported by Na-tionalKey FundamentalResearch and Developing Program, China
文摘Electromagnetic separation of the iron-rich phase inclusions from Al alloy was investigated. The influencing parameters including magnetic induction density, the section shape of the separating channel and the length of influential loop of the metal melt on the separation efficiency of iron-rich phase inclusions were studied. The results show that when the proper magnetic induction density (B=0.3T) is applied, rectangle separating channel is used, and the influential loop of the metal melt is long, high separating efficiency of the iron-rich phase inclusions can be obtained.
基金supported by the National Natural Science Foundation of China(No.512711101)the National Basic Research Program of China (No.2012CB825702)
文摘A new method has been proposed to prepare Mg-A1-Si master alloys by utilizing scrap AI-Si-Fe alloys with higher Fe levels, which aims to segregate Fe from AI-Si-Fe alloys by Mg melt. The segregation be- haviors, microstructure morphology and evolution mechanism of iron-rich phases in Mg-A1-Si alloy melts were studied, after AI-14Si-4Fe （wt%） alloys were added and dissolved completely. In the Mg-A1-Si alloys, iron has very little solubility and tends to combine with other elements to form intermetallic phases, which grow into a deposition layer due to the higher density. During the cooling and solidifying process of Mg-A1-Si melts, the needle-like AlsSiFe phase in AI-14Si-4Fe alloy evolved into blocky AI5Fe2 and Al0.7Fe3Si0.3 phases. Besides, the Fe levels of the Mg-AI-Si master alloys were reduced to 0.017 wt% from nominal content of 0.164 wt%. Based on the above results, this work carried out a semi-quantitative phase- compositions analysis for the deposition layer by relative intensity ratio （RIR） method, and evolution mechanism of the iron-rich phases had also been discussed. This study has paved a new way to regen- erate the scrap AI-Si-Fe alloys, which has a great significance of promoting the recycling of aluminum resources.
文摘The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separation indicates that primary needle-like β phases are difficult to separate; while primary α iron-rich phases can be separated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully when the molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.
文摘Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron（III） oxide（from 25 wt% to 50 wt%）, the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy（SEM）, and X-ray diffraction（XRD） was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.
