Search2022 Vol. 29, No. 9
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2022, vol. 29, no. 9, pp.
1647-1655.
https://doi.org/10.1007/s12613-022-2477-5
Abstract:
Under the background of increasingly scarce ore worldwide and increasingly fierce market competition, developing the mining industry could be strongly restricted. Intelligent ore sorting equipment not only improves ore use and enhances the economic benefits of enterprises but also increases the ore grade and lessens the grinding cost and tailings production. However, long-term research on intelligent ore sorting equipment found that the factors affecting sorting efficiency mainly include ore information identification technology, equipment sorting actuator, and information processing algorithm. The high precision, strong anti-interference capability, and high speed of these factors guarantee the separation efficiency of intelligent ore sorting equipment. Color ore sorter, X-ray ore transmission sorter, dual-energy X-ray transmission ore sorter, X-ray fluorescence ore sorter, and near-infrared ore sorter have been successfully developed in accordance with the different characteristics of minerals while ensuring the accuracy of equipment sorting and improving the equipment sorting efficiency. With the continuous improvement of mine automation level, the application of online element rapid analysis technology with high speed, high precision, and strong anti-interference capability in intelligent ore sorting equipment will become an inevitable trend of equipment development in the future. Laser-induced breakdown spectroscopy, transient γ neutron activation analysis, online Fourier transform infrared spectroscopy, and nuclear magnetic resonance techniques will promote the development of ore sorting equipment. In addition, the improvement and joint application of additional high-speed and high-precision operation algorithms (such as peak area, principal component analysis, artificial neural network, partial least squares, and Monte Carlo library least squares methods) are an essential part of the development of intelligent ore sorting equipment in the future.
Under the background of increasingly scarce ore worldwide and increasingly fierce market competition, developing the mining industry could be strongly restricted. Intelligent ore sorting equipment not only improves ore use and enhances the economic benefits of enterprises but also increases the ore grade and lessens the grinding cost and tailings production. However, long-term research on intelligent ore sorting equipment found that the factors affecting sorting efficiency mainly include ore information identification technology, equipment sorting actuator, and information processing algorithm. The high precision, strong anti-interference capability, and high speed of these factors guarantee the separation efficiency of intelligent ore sorting equipment. Color ore sorter, X-ray ore transmission sorter, dual-energy X-ray transmission ore sorter, X-ray fluorescence ore sorter, and near-infrared ore sorter have been successfully developed in accordance with the different characteristics of minerals while ensuring the accuracy of equipment sorting and improving the equipment sorting efficiency. With the continuous improvement of mine automation level, the application of online element rapid analysis technology with high speed, high precision, and strong anti-interference capability in intelligent ore sorting equipment will become an inevitable trend of equipment development in the future. Laser-induced breakdown spectroscopy, transient γ neutron activation analysis, online Fourier transform infrared spectroscopy, and nuclear magnetic resonance techniques will promote the development of ore sorting equipment. In addition, the improvement and joint application of additional high-speed and high-precision operation algorithms (such as peak area, principal component analysis, artificial neural network, partial least squares, and Monte Carlo library least squares methods) are an essential part of the development of intelligent ore sorting equipment in the future.
2022, vol. 29, no. 9, pp.
1656-1669.
https://doi.org/10.1007/s12613-021-2380-5
Abstract:
Ilmenite is an essential mineral for the extraction of titanium. Conventional physical separation methods have difficulty recovering fine ilmenite, and dressing plants have begun applying flotation to recover ilmenite. The interaction of reagent groups with Ti and Fe sites on the ilmenite surface dramatically influences the ilmenite flotation. However, the investigation on Fe sites has received more attention because the activity of Ti is lower than that of Fe. For the activators on ilmenite flotation, most are metal ions but typically lead ions. The metal ions of activators promote ilmenite flotation by increasing the active sites on the ilmenite surface. Combined reagents have a better selective separation of ilmenite than single reagents due to their synergistic effect. Combining the lead ion (Pb2+) and the benzyl hydroxamic acid (BHA) into a Pb–BHA complex has a marked effect on ilmenite flotation, which puts forward a new idea of developing combined reagents for ilmenite flotation. This review considers reagent types and action mechanisms in ilmenite flotation. On the basis of the analysis of previous research, a brief future outlook of reagent types and action mechanisms in ilmenite flotation is also proposed in this study.
Ilmenite is an essential mineral for the extraction of titanium. Conventional physical separation methods have difficulty recovering fine ilmenite, and dressing plants have begun applying flotation to recover ilmenite. The interaction of reagent groups with Ti and Fe sites on the ilmenite surface dramatically influences the ilmenite flotation. However, the investigation on Fe sites has received more attention because the activity of Ti is lower than that of Fe. For the activators on ilmenite flotation, most are metal ions but typically lead ions. The metal ions of activators promote ilmenite flotation by increasing the active sites on the ilmenite surface. Combined reagents have a better selective separation of ilmenite than single reagents due to their synergistic effect. Combining the lead ion (Pb2+) and the benzyl hydroxamic acid (BHA) into a Pb–BHA complex has a marked effect on ilmenite flotation, which puts forward a new idea of developing combined reagents for ilmenite flotation. This review considers reagent types and action mechanisms in ilmenite flotation. On the basis of the analysis of previous research, a brief future outlook of reagent types and action mechanisms in ilmenite flotation is also proposed in this study.
2022, vol. 29, no. 9, pp.
1670-1682.
https://doi.org/10.1007/s12613-021-2403-2
Abstract:
Circulating fluidized bed fly ash (CFBFA) is a solid waste product from circulating fluidized bed (CFB) boilers in power plants, and the storage of CFBFA is increasingly become an environmental problem. Previous scholars have made contributions to improve the resource utilization of CFBFA. Especially, ecological cement is prepared by CFBFA, which is more conducive to its large-scale utilization. In recent years, a lot of effort has been paid to improve the properties of ecological cement containing CFBFA. In this work, the physicochemical properties of CFBFA are introduced, and recent research progress on the mechanical, expansion, and rheological properties of CFBFA based ecological cement (CEC) is extensively reviewed. The problem of over- expansion of f-CaO is summarized, which limits the scale application of CFBFA in ecological cement. Hence, the challenge for f-CaO in CFBFA to compensate for cement volume shrinkage is proposed, which is beneficial to the utilization of CFBFA in ecological cement, and the reduction of CO2 emissions from the cement industry. In addition, the environmental performance, durability, and economy of CEC should be valued in future research, especially the environmental performance, because the CFBFA contains heavy metals, such as Cr, As, which may pollute groundwater.
Circulating fluidized bed fly ash (CFBFA) is a solid waste product from circulating fluidized bed (CFB) boilers in power plants, and the storage of CFBFA is increasingly become an environmental problem. Previous scholars have made contributions to improve the resource utilization of CFBFA. Especially, ecological cement is prepared by CFBFA, which is more conducive to its large-scale utilization. In recent years, a lot of effort has been paid to improve the properties of ecological cement containing CFBFA. In this work, the physicochemical properties of CFBFA are introduced, and recent research progress on the mechanical, expansion, and rheological properties of CFBFA based ecological cement (CEC) is extensively reviewed. The problem of over- expansion of f-CaO is summarized, which limits the scale application of CFBFA in ecological cement. Hence, the challenge for f-CaO in CFBFA to compensate for cement volume shrinkage is proposed, which is beneficial to the utilization of CFBFA in ecological cement, and the reduction of CO2 emissions from the cement industry. In addition, the environmental performance, durability, and economy of CEC should be valued in future research, especially the environmental performance, because the CFBFA contains heavy metals, such as Cr, As, which may pollute groundwater.
2022, vol. 29, no. 9, pp.
1683-1696.
https://doi.org/10.1007/s12613-022-2439-y
Abstract:
High-entropy alloys (HEAs) are suitable for engineering applications requiring excellent mechanical, corrosion, thermal, and magnetic properties. In the last decade, electrodeposition has emerged as a promising synthesis technique for HEAs. Research has focused on the influence of procedure parameters on the deposition of different HEA layers and the effect of their microstructure on their corrosion and magnetic properties. This review of current literature provides comprehensive information on HEAs and the use of direct and pulse electrodeposition as a synthesis technique for these materials. This review also addresses the research gaps on HEA production via electrodeposition, such as using other ceramic particles instead of graphene oxide in composite structures based on HEAs.
High-entropy alloys (HEAs) are suitable for engineering applications requiring excellent mechanical, corrosion, thermal, and magnetic properties. In the last decade, electrodeposition has emerged as a promising synthesis technique for HEAs. Research has focused on the influence of procedure parameters on the deposition of different HEA layers and the effect of their microstructure on their corrosion and magnetic properties. This review of current literature provides comprehensive information on HEAs and the use of direct and pulse electrodeposition as a synthesis technique for these materials. This review also addresses the research gaps on HEA production via electrodeposition, such as using other ceramic particles instead of graphene oxide in composite structures based on HEAs.
2022, vol. 29, no. 9, pp.
1697-1704.
https://doi.org/10.1007/s12613-021-2313-3
Abstract:
Since the physical and chemical properties of apatite and dolomite can be similar, the separation of these two minerals is difficult. Therefore, when performing this separation using the flotation method, it is necessary to search for selective depressants. An experimental research was performed on the separation behavior of apatite and dolomite using calcium lignosulfonate as a depressant, and the mechanism by which this occurs was analyzed. The results show that calcium lignosulfonate has a depressant effect on both apatite and dolomite, but the depressant effect on dolomite is stronger at the same dosage. Mechanism analysis shows that the adsorptive capacity of calcium lignosulfonate on dolomite is higher than that of apatite, which is due to the strong reaction between calcium lignosulfonate and the Ca sites on dolomite. In addition, there is a hydrogen bond between calcium lignosulfonate and dolomite, which further prevents the adsorption of sodium oleate to dolomite, thus greatly inhibiting the flotation of dolomite.
Since the physical and chemical properties of apatite and dolomite can be similar, the separation of these two minerals is difficult. Therefore, when performing this separation using the flotation method, it is necessary to search for selective depressants. An experimental research was performed on the separation behavior of apatite and dolomite using calcium lignosulfonate as a depressant, and the mechanism by which this occurs was analyzed. The results show that calcium lignosulfonate has a depressant effect on both apatite and dolomite, but the depressant effect on dolomite is stronger at the same dosage. Mechanism analysis shows that the adsorptive capacity of calcium lignosulfonate on dolomite is higher than that of apatite, which is due to the strong reaction between calcium lignosulfonate and the Ca sites on dolomite. In addition, there is a hydrogen bond between calcium lignosulfonate and dolomite, which further prevents the adsorption of sodium oleate to dolomite, thus greatly inhibiting the flotation of dolomite.
2022, vol. 29, no. 9, pp.
1705-1714.
https://doi.org/10.1007/s12613-021-2293-3
Abstract:
An energy-efficient route was adopted to treat titanium-bearing blast furnace slag (TBBFS) in this study. Titanium, aluminum, and magnesium were simultaneously extracted and silicon was separated by low temperature sulfuric acid curing and low concentration sulfuric acid leaching. The process parameters of sulfuric acid curing TBBFS were systematically studied. Under the optimal conditions, the recovery of titanium, aluminum, and magnesium reached 85.96%, 81.17%, and 93.82%, respectively. The rapid leaching model was used to limit the dissolution and polymerization of silicon, and the dissolution of silicon was only 3.18%. The mechanism of sulfuric acid curing–leaching was investigated. During the curing process, the reaction occurred rapidly and released heat massively. Under the attack of hydrogen ions, the structure of TBBFS was destroyed, silicate was depolymerized to form filterable silica, and titanium, magnesium, aluminum, and calcium ions were replaced to form sulfates and enriched on the surface of silica particles. Titanium, aluminum, and magnesium were recovered in the leaching solution, and calcium sulfate and silica were enriched in the residue after leaching. This method could effectively avoid the formation of silica sol during the leaching process and accelerate the solid–liquid separation.
An energy-efficient route was adopted to treat titanium-bearing blast furnace slag (TBBFS) in this study. Titanium, aluminum, and magnesium were simultaneously extracted and silicon was separated by low temperature sulfuric acid curing and low concentration sulfuric acid leaching. The process parameters of sulfuric acid curing TBBFS were systematically studied. Under the optimal conditions, the recovery of titanium, aluminum, and magnesium reached 85.96%, 81.17%, and 93.82%, respectively. The rapid leaching model was used to limit the dissolution and polymerization of silicon, and the dissolution of silicon was only 3.18%. The mechanism of sulfuric acid curing–leaching was investigated. During the curing process, the reaction occurred rapidly and released heat massively. Under the attack of hydrogen ions, the structure of TBBFS was destroyed, silicate was depolymerized to form filterable silica, and titanium, magnesium, aluminum, and calcium ions were replaced to form sulfates and enriched on the surface of silica particles. Titanium, aluminum, and magnesium were recovered in the leaching solution, and calcium sulfate and silica were enriched in the residue after leaching. This method could effectively avoid the formation of silica sol during the leaching process and accelerate the solid–liquid separation.
2022, vol. 29, no. 9, pp.
1715-1721.
https://doi.org/10.1007/s12613-021-2366-3
Abstract:
The effective and low-temperature extraction of lithium from the pyrometallurgical slag of spent lithium-ion batteries (LIBs) remains a great challenge. Herein, potassium carbonate/sodium carbonate (K2CO3/Na2CO3), which could form a eutectic molten salt system at 720°C, was used as a roasting agent to extract lithium from pyrometallurgical slag. Lithium was successfully extracted from the slag by K2CO3/Na2CO3 roasting followed by water leaching. Theoretical calculation results indicate that the lengths of Li–O bonds increase after K+/Na+ adsorption, resulting in the easy release of Li+ from the LiAlSi2O6 lattice after roasting with K2CO3/Na2CO3. Thermogravimetry–differential scanning calorimetry results indicate that the eutectic phenomenon of K2CO3 and Na2CO3 could be observed at 720°C and that the reaction of the slag and eutectic molten salts occurs at temperatures above 720°C. X-ray diffraction results suggest that Li+ in the slag is exchanged by K+ in K2CO3 with the concurrent formation of KAlSiO4, while Na2CO3 mainly functions as a fluxing agent. The lithium extraction efficiency can reach 93.87% under the optimal conditions of a roasting temperature of 740°C, roasting time of 30 min, leaching temperature of 50°C, leaching time of 40 min, and water/roasted sample mass ratio of 10:1. This work provides a new system for extracting lithium from the pyrometallurgical slag of spent LIBs.
The effective and low-temperature extraction of lithium from the pyrometallurgical slag of spent lithium-ion batteries (LIBs) remains a great challenge. Herein, potassium carbonate/sodium carbonate (K2CO3/Na2CO3), which could form a eutectic molten salt system at 720°C, was used as a roasting agent to extract lithium from pyrometallurgical slag. Lithium was successfully extracted from the slag by K2CO3/Na2CO3 roasting followed by water leaching. Theoretical calculation results indicate that the lengths of Li–O bonds increase after K+/Na+ adsorption, resulting in the easy release of Li+ from the LiAlSi2O6 lattice after roasting with K2CO3/Na2CO3. Thermogravimetry–differential scanning calorimetry results indicate that the eutectic phenomenon of K2CO3 and Na2CO3 could be observed at 720°C and that the reaction of the slag and eutectic molten salts occurs at temperatures above 720°C. X-ray diffraction results suggest that Li+ in the slag is exchanged by K+ in K2CO3 with the concurrent formation of KAlSiO4, while Na2CO3 mainly functions as a fluxing agent. The lithium extraction efficiency can reach 93.87% under the optimal conditions of a roasting temperature of 740°C, roasting time of 30 min, leaching temperature of 50°C, leaching time of 40 min, and water/roasted sample mass ratio of 10:1. This work provides a new system for extracting lithium from the pyrometallurgical slag of spent LIBs.
2022, vol. 29, no. 9, pp.
1722-1732.
https://doi.org/10.1007/s12613-021-2299-x
Abstract:
The effective recycling of waste printed circuit boards (WPCBs) can conserve resources and reduce environmental pollution. This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres through thermogravimetric and Gaussian fitting analyses. Furthermore, this study analyses the pyrolysis products and combustion processes of WPCBs through thermogravimetric and Fourier transform infrared analyses (TG–FTIR) and thermogravimetry–mass spectrometry (TG–MS). Results show that the pyrolysis and combustion processes of WPCBs do not constitute a single reaction, but rather an overlap of multiple reactions. The pyrolysis and combustion process of WPCBs is divided into multiple reactions by Gaussian peak fitting. The kinetic parameters of each reaction are obtained by the Coats–Redfern method. In an argon atmosphere, pyrolysis consists of the overlap of the preliminary pyrolysis of epoxy resin, pyrolysis of small organic molecules, and pyrolysis of brominated flame retardants. The thermal decomposition process in the O2 atmosphere is mainly divided into two reactions: brominated flame retardant combustion and epoxy combustion. This study provided the theoretical basis for pollution control, process optimization, and reactor design of WPCBs pyrolysis.
The effective recycling of waste printed circuit boards (WPCBs) can conserve resources and reduce environmental pollution. This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres through thermogravimetric and Gaussian fitting analyses. Furthermore, this study analyses the pyrolysis products and combustion processes of WPCBs through thermogravimetric and Fourier transform infrared analyses (TG–FTIR) and thermogravimetry–mass spectrometry (TG–MS). Results show that the pyrolysis and combustion processes of WPCBs do not constitute a single reaction, but rather an overlap of multiple reactions. The pyrolysis and combustion process of WPCBs is divided into multiple reactions by Gaussian peak fitting. The kinetic parameters of each reaction are obtained by the Coats–Redfern method. In an argon atmosphere, pyrolysis consists of the overlap of the preliminary pyrolysis of epoxy resin, pyrolysis of small organic molecules, and pyrolysis of brominated flame retardants. The thermal decomposition process in the O2 atmosphere is mainly divided into two reactions: brominated flame retardant combustion and epoxy combustion. This study provided the theoretical basis for pollution control, process optimization, and reactor design of WPCBs pyrolysis.
2022, vol. 29, no. 9, pp.
1733-1745.
https://doi.org/10.1007/s12613-021-2369-0
Abstract:
This work studied the effects of adding Zr and Mn in amounts less than 1wt% on the microstructure, mechanical properties, casting properties, and corrosion resistance of Mg–Zn–Cu alloys containing 2.5wt% Cu and 2.5wt%–6.5wt% Zn. The hardness and electrical conductivity measurements were used to find an optimal heat treatment schedule with the best mechanical properties. It has been established that Zr significantly increases the yield strength of the alloys due to a strong grain refinement effect. However, the presence of Mn and Zr has a detrimental effect on alloy’s elongation at fracture. It was shown that the precipitation of the Mg2Cu cathodic phase in the alloy structure negatively affects the corrosion behavior. Nevertheless, the addition of Mn decreases the corrosion rate of the investigated alloys. The best combination of the mechanical, casting, and corrosion properties were achieved in the alloys containing 2.5wt% Cu and 5wt% Zn. However, the Mn or Zr addition can improve the properties of the alloys; for example, the addition of Mn or Zr increases the fluidity of the alloys.
This work studied the effects of adding Zr and Mn in amounts less than 1wt% on the microstructure, mechanical properties, casting properties, and corrosion resistance of Mg–Zn–Cu alloys containing 2.5wt% Cu and 2.5wt%–6.5wt% Zn. The hardness and electrical conductivity measurements were used to find an optimal heat treatment schedule with the best mechanical properties. It has been established that Zr significantly increases the yield strength of the alloys due to a strong grain refinement effect. However, the presence of Mn and Zr has a detrimental effect on alloy’s elongation at fracture. It was shown that the precipitation of the Mg2Cu cathodic phase in the alloy structure negatively affects the corrosion behavior. Nevertheless, the addition of Mn decreases the corrosion rate of the investigated alloys. The best combination of the mechanical, casting, and corrosion properties were achieved in the alloys containing 2.5wt% Cu and 5wt% Zn. However, the Mn or Zr addition can improve the properties of the alloys; for example, the addition of Mn or Zr increases the fluidity of the alloys.
2022, vol. 29, no. 9, pp.
1746-1754.
https://doi.org/10.1007/s12613-021-2327-x
Abstract:
The effects of trace yttrium (Y) element on the microstructure, mechanical properties, and corrosion resistance of Mg–2Zn–0.1Mn–0.3Ca–xY (x = 0, 0.1, 0.2, 0.3) biological magnesium alloys are investigated. Results show that grain size decreases from 310 to 144 μm when Y content increases from 0wt% to 0.3wt%. At the same time, volume fraction of the second phase increases from 0.4% to 6.0%, yield strength of the alloy continues to increase, and ultimate tensile strength and elongation decrease initially and then increase. When the Y content increases to 0.3wt%, Mg3Zn6Y phase begins to precipitate in the alloy; thus, the alloy exhibits the most excellent mechanical property. At this time, its ultimate tensile strength, yield strength, and elongation are 119 MPa, 69 MPa, and 9.1%, respectively. In addition, when the Y content is 0.3wt%, the alloy shows the best corrosion resistance in the simulated body fluid (SBF). This investigation has revealed that the improvement of mechanical properties and corrosion resistance is mainly attributed to the grain refinement and the precipitated Mg3Zn6Y phase.
The effects of trace yttrium (Y) element on the microstructure, mechanical properties, and corrosion resistance of Mg–2Zn–0.1Mn–0.3Ca–xY (x = 0, 0.1, 0.2, 0.3) biological magnesium alloys are investigated. Results show that grain size decreases from 310 to 144 μm when Y content increases from 0wt% to 0.3wt%. At the same time, volume fraction of the second phase increases from 0.4% to 6.0%, yield strength of the alloy continues to increase, and ultimate tensile strength and elongation decrease initially and then increase. When the Y content increases to 0.3wt%, Mg3Zn6Y phase begins to precipitate in the alloy; thus, the alloy exhibits the most excellent mechanical property. At this time, its ultimate tensile strength, yield strength, and elongation are 119 MPa, 69 MPa, and 9.1%, respectively. In addition, when the Y content is 0.3wt%, the alloy shows the best corrosion resistance in the simulated body fluid (SBF). This investigation has revealed that the improvement of mechanical properties and corrosion resistance is mainly attributed to the grain refinement and the precipitated Mg3Zn6Y phase.
2022, vol. 29, no. 9, pp.
1755-1769.
https://doi.org/10.1007/s12613-022-2506-4
Abstract:
Single-pass deposits of 6061 aluminum alloy with a single-layer thickness of 4 mm were fabricated by force-controlled friction- and extrusion-based additive manufacturing. The formation characteristics of the interface, which were achieved by using a featureless shoulder, were investigated and elucidated. The microstructure and bonding strength of the final build both with and without heat treatment were explored. A pronounced microstructural heterogeneity was observed throughout the thickness of the final build. Grains at the interface with Cu, {213}<111>, and Goss orientations prevailed, which were refined to approximately 4.0 μm. Nearly all of the hardening precipitates were dissolved, resulting in the bonding interface displaying the lowest hardness. The fresh layer, subjected to thermal processes and plastic deformation only once, was dominated by a strong recrystallization texture with a Cube orientation. The previous layer, subjected twice to thermal processes and plastic deformation, was governed by P- and Goss-related components. The ultimate tensile strength along the build direction in as-deposited and heat-treated states could reach 57.0% and 82.9% of the extruded 6061-T651 aluminum alloy.
Single-pass deposits of 6061 aluminum alloy with a single-layer thickness of 4 mm were fabricated by force-controlled friction- and extrusion-based additive manufacturing. The formation characteristics of the interface, which were achieved by using a featureless shoulder, were investigated and elucidated. The microstructure and bonding strength of the final build both with and without heat treatment were explored. A pronounced microstructural heterogeneity was observed throughout the thickness of the final build. Grains at the interface with Cu, {213}<111>, and Goss orientations prevailed, which were refined to approximately 4.0 μm. Nearly all of the hardening precipitates were dissolved, resulting in the bonding interface displaying the lowest hardness. The fresh layer, subjected to thermal processes and plastic deformation only once, was dominated by a strong recrystallization texture with a Cube orientation. The previous layer, subjected twice to thermal processes and plastic deformation, was governed by P- and Goss-related components. The ultimate tensile strength along the build direction in as-deposited and heat-treated states could reach 57.0% and 82.9% of the extruded 6061-T651 aluminum alloy.
2022, vol. 29, no. 9, pp.
1770-1779.
https://doi.org/10.1007/s12613-021-2287-1
Abstract:
Many studies have investigated the selective laser melting (SLM) of AlSi10Mg and AlSi7Mg alloys, but there are still lack of researches focused on Al–Si–Mg alloys specifically tailored for SLM. In this work, a novel high Mg-content AlSi8Mg3 alloy was specifically designed for SLM. The results showed that this new alloy exhibited excellent SLM processability with a lowest porosity of 0.07%. Massive lattice distortion led to a high Vickers hardness in samples fabricated at a high laser power due to the precipitation of Mg2Si nanoparticles from the α-Al matrix induced by high-intensity intrinsic heat treatment during SLM. The maximum microhardness and compressive yield strength of the alloy reached HV (211 ± 4) and (526 ± 12) MPa, respectively. After aging treatment at 150°C, the maximum microhardness and compressive yield strength of the samples were further improved to HV (221 ± 4) and (577 ± 5) MPa, respectively. These values are higher than those of most known aluminum alloys fabricated by SLM. This paper provides a new idea for optimizing the mechanical properties of Al–Si–Mg alloys fabricated using SLM.
Many studies have investigated the selective laser melting (SLM) of AlSi10Mg and AlSi7Mg alloys, but there are still lack of researches focused on Al–Si–Mg alloys specifically tailored for SLM. In this work, a novel high Mg-content AlSi8Mg3 alloy was specifically designed for SLM. The results showed that this new alloy exhibited excellent SLM processability with a lowest porosity of 0.07%. Massive lattice distortion led to a high Vickers hardness in samples fabricated at a high laser power due to the precipitation of Mg2Si nanoparticles from the α-Al matrix induced by high-intensity intrinsic heat treatment during SLM. The maximum microhardness and compressive yield strength of the alloy reached HV (211 ± 4) and (526 ± 12) MPa, respectively. After aging treatment at 150°C, the maximum microhardness and compressive yield strength of the samples were further improved to HV (221 ± 4) and (577 ± 5) MPa, respectively. These values are higher than those of most known aluminum alloys fabricated by SLM. This paper provides a new idea for optimizing the mechanical properties of Al–Si–Mg alloys fabricated using SLM.
2022, vol. 29, no. 9, pp.
1780-1787.
https://doi.org/10.1007/s12613-021-2322-2
Abstract:
Laser shock peening (LSP) is an attractive post-processing method to tailor surface microstructure and enhance mechanical performances of additive manufactured (AM) components. The effects of multiple LSP treatments on the microstructure and mechanical properties of Ti–6Al–4V part produced by electron beam melting (EBM), as a mature AM process, were studied in this work. Microstructure, surface topography, residual stress, and tensile performance of EBM-manufactured Ti–6Al–4V specimens were systematically analyzed subjected to different LSP treatments. The distribution of porosities in EBM sample was assessed via X-ray computed tomography. The results showed that EBM samples with two LSP treatments possessed a lower porosity value of 0.05% compared to the value of 0.08% for the untreated samples. The strength of EBM samples with two LSP treatments was remarkably raised by 12% as compared with the as-built samples. The grains of α phase were refined in near-surface layer, and a dramatic increase in the depth and magnitude of compressive residual stress (CRS) was achieved in EBM sample with multiple LSP treatments. The grain refinement of α phase and CRS with larger depth were responsible for the strength enhancement of EBM samples with two LSP treatments.
Laser shock peening (LSP) is an attractive post-processing method to tailor surface microstructure and enhance mechanical performances of additive manufactured (AM) components. The effects of multiple LSP treatments on the microstructure and mechanical properties of Ti–6Al–4V part produced by electron beam melting (EBM), as a mature AM process, were studied in this work. Microstructure, surface topography, residual stress, and tensile performance of EBM-manufactured Ti–6Al–4V specimens were systematically analyzed subjected to different LSP treatments. The distribution of porosities in EBM sample was assessed via X-ray computed tomography. The results showed that EBM samples with two LSP treatments possessed a lower porosity value of 0.05% compared to the value of 0.08% for the untreated samples. The strength of EBM samples with two LSP treatments was remarkably raised by 12% as compared with the as-built samples. The grains of α phase were refined in near-surface layer, and a dramatic increase in the depth and magnitude of compressive residual stress (CRS) was achieved in EBM sample with multiple LSP treatments. The grain refinement of α phase and CRS with larger depth were responsible for the strength enhancement of EBM samples with two LSP treatments.
2022, vol. 29, no. 9, pp.
1788-1797.
https://doi.org/10.1007/s12613-021-2303-5
Abstract:
The study explores the excellent modification effect of Nb nanocatalyst prepared via surfactant assisted ball milling technique (SABM) on the hydrogen storage properties of MgH2. Optimal catalyst doping concentration was determined by comparing onset decomposition temperature, released hydrogen capacity, and reaction rate for different MgH2–ywt%Nb (y = 0, 3, 5, 7, 9) composites. The MgH2–5wt%Nb composite started releasing hydrogen at 186.7°C and a total of 7.0wt% hydrogen was released in the dehydrogenation process. In addition, 5wt% Nb doped MgH2 also managed to release 4.2wt% H2 within 14 min at 250°C and had the ability to absorb 4.0wt% hydrogen in 30 min at 100°C. Cycling tests revealed that MgH2–5wt%Nb could retain 6.3wt% H2 storage capacity (89.2%) after 20 cycles. Dehydrogenation and hydrogenation activation energy values were decreased from 140.51±4.74 and 70.67±2.07 kJ·mol−1 to 90.04±2.83 and 53.46±3.33 kJ·mol−1 after doping MgH2 with Nb, respectively. Microstructure analysis proved that homogeneously distributed NbH acted as active catalytic unit for improving the hydrogen storage performance of MgH2. These results indicate SABM can be considered as an option to develop other nanocatalysts for energy related areas.
The study explores the excellent modification effect of Nb nanocatalyst prepared via surfactant assisted ball milling technique (SABM) on the hydrogen storage properties of MgH2. Optimal catalyst doping concentration was determined by comparing onset decomposition temperature, released hydrogen capacity, and reaction rate for different MgH2–ywt%Nb (y = 0, 3, 5, 7, 9) composites. The MgH2–5wt%Nb composite started releasing hydrogen at 186.7°C and a total of 7.0wt% hydrogen was released in the dehydrogenation process. In addition, 5wt% Nb doped MgH2 also managed to release 4.2wt% H2 within 14 min at 250°C and had the ability to absorb 4.0wt% hydrogen in 30 min at 100°C. Cycling tests revealed that MgH2–5wt%Nb could retain 6.3wt% H2 storage capacity (89.2%) after 20 cycles. Dehydrogenation and hydrogenation activation energy values were decreased from 140.51±4.74 and 70.67±2.07 kJ·mol−1 to 90.04±2.83 and 53.46±3.33 kJ·mol−1 after doping MgH2 with Nb, respectively. Microstructure analysis proved that homogeneously distributed NbH acted as active catalytic unit for improving the hydrogen storage performance of MgH2. These results indicate SABM can be considered as an option to develop other nanocatalysts for energy related areas.
2022, vol. 29, no. 9, pp.
1798-1808.
https://doi.org/10.1007/s12613-021-2345-8
Abstract:
Bi0.5(Na0.68K0.22Li0.10)0.5Ti1–xCoxO3 lead-free perovskite ceramics (BNKLT–xCo, x = 0, 0.005, 0.010, 0.015 and 0.020) were fabricated via the solid-state combustion technique. A small-amount of Co2+ ion substitution into Ti-sites led to modification of the phase formation, microstructure, electrical and magnetic properties of BNKLT ceramics. Coexisting rhombohedral and tetragonal phases were observed in all samples using the X-ray diffraction (XRD) technique. The Rietveld refinement revealed that the rhombohedral phase increased from 39% to 88% when x increased from 0 to 0.020. The average grain size increased when x increased. With increasing x, more oxygen vacancies were generated, leading to asymmetry in the bipolar strain (S–E) hysteresis loops. For the composition of x = 0.010, a high dielectric constant (εm) of 5384 and a large strain (Smax) of 0.23% with the normalized strain\begin{document}$ \left({d}_{33}^{*}\right) $\end{document} ![]()
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Bi0.5(Na0.68K0.22Li0.10)0.5Ti1–xCoxO3 lead-free perovskite ceramics (BNKLT–xCo, x = 0, 0.005, 0.010, 0.015 and 0.020) were fabricated via the solid-state combustion technique. A small-amount of Co2+ ion substitution into Ti-sites led to modification of the phase formation, microstructure, electrical and magnetic properties of BNKLT ceramics. Coexisting rhombohedral and tetragonal phases were observed in all samples using the X-ray diffraction (XRD) technique. The Rietveld refinement revealed that the rhombohedral phase increased from 39% to 88% when x increased from 0 to 0.020. The average grain size increased when x increased. With increasing x, more oxygen vacancies were generated, leading to asymmetry in the bipolar strain (S–E) hysteresis loops. For the composition of x = 0.010, a high dielectric constant (εm) of 5384 and a large strain (Smax) of 0.23% with the normalized strain
2022, vol. 29, no. 9, pp.
1809-1816.
https://doi.org/10.1007/s12613-021-2309-z
Abstract:
Since ultraviolet (UV) light, as well as blue light, which is part of visible light, is harmful to skin, samarium–cerium compounds containing Sm2O2S were synthesized by co-precipitation method. This kind of compounds blocks not only UV light, but also blue light. The minimum values of average transmittance (360–450 nm) and band gap of samarium–cerium compounds were 8.90% and 2.76 eV, respectively, which were less than 13.96% and 3.01 eV of CeO2. Elemental analysis (EA), X-ray diffraction (XRD), Fourier transformation infrared (FTIR), and Raman spectra determined that the samples contained Ce4O7, Sm2O2S, Sm2O3, and Sm2O2SO4. The microstructure of samples was analyzed by scanning and transmission electron microscopies (SEM and TEM). X-ray photoelectron spectrum (XPS) showed that cerium had Ce3+ and Ce4+ valence states, and oxygen was divided into lattice oxygen and oxygen vacancy, which was the direct cause of the decrease of average transmittance and band gap.
Since ultraviolet (UV) light, as well as blue light, which is part of visible light, is harmful to skin, samarium–cerium compounds containing Sm2O2S were synthesized by co-precipitation method. This kind of compounds blocks not only UV light, but also blue light. The minimum values of average transmittance (360–450 nm) and band gap of samarium–cerium compounds were 8.90% and 2.76 eV, respectively, which were less than 13.96% and 3.01 eV of CeO2. Elemental analysis (EA), X-ray diffraction (XRD), Fourier transformation infrared (FTIR), and Raman spectra determined that the samples contained Ce4O7, Sm2O2S, Sm2O3, and Sm2O2SO4. The microstructure of samples was analyzed by scanning and transmission electron microscopies (SEM and TEM). X-ray photoelectron spectrum (XPS) showed that cerium had Ce3+ and Ce4+ valence states, and oxygen was divided into lattice oxygen and oxygen vacancy, which was the direct cause of the decrease of average transmittance and band gap.
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