The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In...The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.展开更多
The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and develop...The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and development over the years in order to stay ahead of their competitors.Lightweight materials are critical in defence applications because they allow components to be lighter without sacrificing strength.This review provides an overview of the research related to defence applications.The book provides comprehensive details on current trends in the application of lightweight materials in defence.This review also includes historical and current perspectives on defence technologies.It discusses uses of lightweight materials such as metal matrix composites,polymer composites,ceramic matrix composites,fiber composites in defence sectors Finally,the review paper also emphasizes future military applications of lightweight materials.展开更多
With the development of new energy vehicles, the continuous application of new materials and new technology in the automobile industry. In order to realize the requirements of energy conservation and emission reductio...With the development of new energy vehicles, the continuous application of new materials and new technology in the automobile industry. In order to realize the requirements of energy conservation and emission reduction, new energy vehicles must be lightweight and designed, and the development of automobile lightweight materials is an important aspect of the development of automobile technology. The lightweight of the car should reduce its own weight as much as possible on the premise of protecting its own strength and safety performance. As one of the main components of the car, the lightweight effect has an important impact on the lightweight design of the vehicle. This paper introduces the common lightweight materials of the body and analyzes the application of lightweight materials for the main parts of the body, which can provide some reference for the study of lightweight design of hybrid material body.展开更多
In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance ...In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance of lightweight concrete.Through a mixture design approach,five formulations were selected and thoroughly characterized.The analysis of iso-response curves enabled an in-depth assessment of the cross-effects between formulation parameters and their interactions on the final properties of the material.The results show that integrating millet husks leads to a significant reduction in density,reaching up to 21%,while maintaining notable mechanical performance.A balanced formulation of sand and fibers achieved a maximum compressive strength of 12.11 MPa,demonstrating that,under specific conditions,plant fibers actively contribute to the structural integrity of the composite.In tensile strength,the positive influence of fibers is even more pronounced,with a maximum resistance of 8.62 MPa,highlighting their role in enhancing material cohesion.From a thermal perspective,millet husks reduce both thermal conductivity and effusivity,thereby limiting heat transfer and accumulation within the composite.Iso-response curve analysis reveals that these effects are directly linked to the proportions of the constituents and that achieving an optimal balance between sand,fibers,and cement is key to maximizing performance.These findings demonstrate that the adopted approach allows moving beyond conventional substitution methods by identifying optimal configurations for the design of lightweight bio-based concretes that are both strong and insulating,thereby confirming the potential of millet husks in developing lightweight concretes suitable for sustainable construction applications.展开更多
Damage evolution characterization and performance evaluation under realistic conditions are essential to ensure reliable operation of critical safety components.However,previous studies focus on the surface detection ...Damage evolution characterization and performance evaluation under realistic conditions are essential to ensure reliable operation of critical safety components.However,previous studies focus on the surface detection because of very limited penetration capacity of nondestructive testing facilities.Here,we review the recent progress of material damage mechanism by various in situ testing rigs that are compat-ible with laboratory and synchrotron radiation X-ray facilities.Then,taking metallic alloys and composites as model materials,we demonstrate the unique advantages of in situ X-ray three-dimensional tomography in unveiling complex failure mechanisms,quantifying crack growth driving forces and crack closure phenomena,and elucidating the strengthening/degrading effects from microstructure and environment on structural material degradation.Finally,we also discuss the ongoing direction of in situ multi-scale visualization and characterization with the development of advanced high-energy X-ray facilities,the improvement of in situ devices and sample environments,the demand of high-throughput tests,and the processing and application of massive test data.展开更多
With the increased electromagnetic wave(EMW)threat to military and human health,the develop-ment of EMW-absorbing materials is crucial.Metal-organic framework derivatives containing magnetic nanoparticles and a carbon...With the increased electromagnetic wave(EMW)threat to military and human health,the develop-ment of EMW-absorbing materials is crucial.Metal-organic framework derivatives containing magnetic nanoparticles and a carbon matrix are potential candidates for designing efficient EMW-absorbing mate-rials.Herein,a zeolitic imidazolate framework-67(ZIF-67)-embedded three-dimensional melamine foam is pyrolyzed to afford carbon foam-based nitrogen-doped carbon nanotube composites,named 3D foam-like CoO/Co/N-CNTs.Magnetic CoO/Co particles are confined in the dielectric carbon nanotube skeleton.The carbon nanotubes provide considerable conductive loss,while CoO/Co magnetic particles are con-ducive to providing magnetic loss and adjusting impedance matching.Moreover,the numerous defect structures introduced by heteroatomic doping(nitrogen)cause dipole polarization and simultaneously adjust impedance matching.Meanwhile,the unique porous nanotube structure promotes multiple re-flections and scattering of EMWs,further optimizing impedance matching.CoO/Co/N-CNTs composites exhibit a minimum reflection loss of−52.3 dB at a matching thickness of 2.0 mm,while the correspond-ing effective absorption bandwidth is 5.28 GHz at a matching thickness of 2.2 mm.This study reports a novel approach to fabricating a lightweight high-performance EMW-absorbing material.展开更多
To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using...To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using pyrophyl-lite, .fly ash, and Suzhou clay as the main starting materials and saw dast as the pore forming substance, and controlling the addition of the pyrophyllite （20%, 30% , and 40% by mass ） and the treating temperature （1 250, 1 300, 1 350, and 1 400 ℃ ）. The synthesized materials were characterized by the XRD, SEM and the thermal conductivity measuring in.strument. The results show at pyrophyllite addition of 30% and treat temperature of l 400 ℃ , the material can achieve linear shrinkage of 6. 6%, apparent porosity of 57%, bulk density of 0. 75 g · cm^-3, compressive strength of 2.7 MPa, and thermal conductivity at 350 ℃ of 0. 152 -0. 216 W·（ m·K）^-1.This indicates that the pyrophyllite decomposition at high temperatures forms mullite and amorphous quartz introducing volume expansion, which counteracts some shrinkage at high temperatures. So it is feasible to use pyrophyllite, fly ash waste and clay to prepare lightweight insulation refractory materials.展开更多
Titanium(Ti)alloys are widely used in high-tech fields like aerospace and biomedical engineering.Laser additive manufacturing(LAM),as an innovative technology,is the key driver for the development of Ti alloys.Despite...Titanium(Ti)alloys are widely used in high-tech fields like aerospace and biomedical engineering.Laser additive manufacturing(LAM),as an innovative technology,is the key driver for the development of Ti alloys.Despite the significant advancements in LAM of Ti alloys,there remain challenges that need further research and development efforts.To recap the potential of LAM high-performance Ti alloy,this article systematically reviews LAM Ti alloys with up-to-date information on process,materials,and properties.Several feasible solutions to advance LAM Ti alloys are reviewed,including intelligent process parameters optimization,LAM process innovation with auxiliary fields and novel Ti alloys customization for LAM.The auxiliary energy fields(e.g.thermal,acoustic,mechanical deformation and magnetic fields)can affect the melt pool dynamics and solidification behaviour during LAM of Ti alloys,altering microstructures and mechanical performances.Different kinds of novel Ti alloys customized for LAM,like peritecticα-Ti,eutectoid(α+β)-Ti,hybrid(α+β)-Ti,isomorphousβ-Ti and eutecticβ-Ti alloys are reviewed in detail.Furthermore,machine learning in accelerating the LAM process optimization and new materials development is also outlooked.This review summarizes the material properties and performance envelops and benchmarks the research achievements in LAM of Ti alloys.In addition,the perspectives and further trends in LAM of Ti alloys are also highlighted.展开更多
Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating...Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating refractories were prepared by the molten salt method with high silica magnesite and tertiary talc ore as raw materials by pretreating them to get light burnt magnesia and talc,and NaCl molten salt as the reaction medium.The effects of the NaCl addition,the sintering temperature,the holding time and the raw material ratio on the sample preparation were studied.The results show that when the NaCl addition is 20% of the mass of light burnt magnesia and talc mixture,the sintering temperature is 1 200 ℃,the holding time is 6 h,and m(light burnt magnesia):m(talc)=5:5,the sample has the optimal comprehensive properties:the bulk density of 1.46 g·cm^(-3) and the apparent porosity of 55.0%.In addition,it is found that self-decomposition of talc and the formation of forsterite can form pores inside the sample.展开更多
Developing lightweight lattice materials that possess exceptional strength,stiffness,and toughness(or energy absorption)simultaneously remains a significant challenge.In this study,we develop a novel design strategy:i...Developing lightweight lattice materials that possess exceptional strength,stiffness,and toughness(or energy absorption)simultaneously remains a significant challenge.In this study,we develop a novel design strategy:incorporating nonlocal interactions into lattice beams,creating“nonlocal lattices”.Utilizing simulation experiments,we investigated the bending behaviors of these lattices,with a particular focus on their damage evolution.Interestingly,these nonlocal lattices,categorized as stretch-dominated,exhibit extraordinary peak force(strength)and stiffness(modulus)comparable to traditional stretchdominated lattices,while maintaining superior energy absorption(toughness).Analysis of damage evolution within the lattice beams reveals a transition from localized to dispersed damage patterns.This transition delays strain localization,thereby improving material utilization efficiency.Furthermore,stronger nonlocal interaction leads to a more dispersed damage zone,further improving materials utilization efficiency.These findings demonstrate that nonlocal lattices achieve excellent energy dissipation(toughness)without compromising strength and stiffness.This highlights the crucial role of nonlocal interactions in governing strain localization within lattice materials.The design strategy here unlocks new inspirations for the development of strong and tough lightweight materials.展开更多
Foamed waste glass(FWG) material is newly developed for the purpose to utilize the waste glassware and other waste glass. FWG has a multi-porous structure that consists of continuous or discontinuous voids. Hence ligh...Foamed waste glass(FWG) material is newly developed for the purpose to utilize the waste glassware and other waste glass. FWG has a multi-porous structure that consists of continuous or discontinuous voids. Hence lightweight but considerable stiffness can be achieved. In the present study, the manufacture and engineering properties of FWG are introduced first. Then, the utilizations of FWG are investigated in laboratory tests and field tests. Some case studies on design and construction work are also reported here. Through these studies we know that the discontinuous void material can be utilized as a lightweight fill material, ground improvement material and lightweight aggregate for concrete. On the other hand, the continuous void material can be used as water holding material for the greening of ground slope and rooftop, and as clarification material for water.展开更多
In this work,zeolitic imidazolate framework-8(ZIF-8)with yolk-shell and hollow structures were pre-pared by a convenient chemical etching method.A subsequent pyrolysis of ZIF-8 enabled one to pro-duce ZnO/nitrogen-dop...In this work,zeolitic imidazolate framework-8(ZIF-8)with yolk-shell and hollow structures were pre-pared by a convenient chemical etching method.A subsequent pyrolysis of ZIF-8 enabled one to pro-duce ZnO/nitrogen-doped carbon nanocomplexes with original ZIF-8 morphology,where hollow struc-ture showed superior electromagnetic wave absorption capacity and was responsible for matching the impedance of free space.The minimum reflection coefficients of hollow ZnO/nitrogen-doped carbon nanocomplexes were-51.2 dB(700℃)and-52.4 dB(800℃),respectively,whereas the effective ab-sorption band width was as large as 4 GHz and the content of pyrolyzed hollow ZIF-8 was 15 wt%,which was inferior to the level among similar electromagnetic wave(EMW)absorption materials.The conve-nient and facile strategy paves the way toward designing hierarchical structures for highly efficient and light-weight electromagnetic wave absorbers.展开更多
The surface of hollow glass microspheres (HGMs) was roughened by a HCl+NH_(4)F strategy,which achieved a broken ratio as 16.10%,and then metallized by electroless plating by Co nanoparticles up to 90 wt% (abbreviated ...The surface of hollow glass microspheres (HGMs) was roughened by a HCl+NH_(4)F strategy,which achieved a broken ratio as 16.10%,and then metallized by electroless plating by Co nanoparticles up to 90 wt% (abbreviated as Co-HGMs).The average grain size of Co was measured to range from 0.4 to 0.5 μm.Then Co-HGMs were mixed with liquid silicone rubber and xylene,and cured on a perspex plate applicable for flexible electromagnetic shielding.By attentive parameter optimization,a film about 0.836 mm in thickness was obtained with a density of 0.729 g/cm^(3),showing a shielding effectiveness of 15.2 dB in the X-band (8.2-12.4 GHz) at room temperature,which was ascribed to the formation of a conductive network of Co-HGMs inside the film.Simultaneously,the tensile strength of 0.89 MPa at an elongation ratio of 194.5% was also obtained,showing good mechanical properties and tensile strength.展开更多
Light-weighting involves the use of advanced materials and engineering methods to enable structural elements to deliver the same,or enhanced,technical performance while using less material.The concept has been extensi...Light-weighting involves the use of advanced materials and engineering methods to enable structural elements to deliver the same,or enhanced,technical performance while using less material.The concept has been extensively explored and utilised in many industries from automotive applications to fashion and packaging and offers significant potential in the aviation sector.Typical implementations of light-weighting have involved use of high performance materials such as composites and optimisation of structures using computational aided engineering approaches with production enabled by advanced manufacturing methods such as additive manufacture,foam metals and hot forming.This paper reviews the principal approaches used in light-weighting,along with the scope for application of light-weighting in aviation applications from power-plants to airframe components.A particular area identified as warranting attention and amenable to the use of lightweighting approaches is the design of solar powered aircraft wings.The high aspect ratio typically used for these can be associated with insufficient stiffness,giving rise to non-linear deformation,aileron reversal,flutter and rigid-elastic coupling.Additional applications considered include ultralight aviation components and sub-systems,UAVs,and rockets.Advanced optimisation approaches can be applied to optimise the layout of structural elements,as well as geometrical parameters in order to maximise structural stiffness,minimise mass and enable incorporation of energy storage features.The use of additive manufacturing technologies,some capable of producing composite or multi-material components is an enabler for light-weighting,as features formally associated with one principal function can be designed to fulfil multiple functionalities。展开更多
WT5”BZ]In this study, by considering the scale ratio related to the specific gravity of the submerged bed material, and introducing a degree of distortion, n the similarity laws for a distorted river model with a mov...WT5”BZ]In this study, by considering the scale ratio related to the specific gravity of the submerged bed material, and introducing a degree of distortion, n the similarity laws for a distorted river model with a movable bed were derived under the conditions that the values of dual dimensionless parameters in a regime-criterion diagram for the bars are the same in a model as they are in a prototype, and that a resistance law such as the Manning-Strickler-type formula is to be valid for a model and a prototype. The usefulness of the similarity laws derived in this study was verified by comparing the bed forms from the distroted model experiments with the bed forms from the 1/50-scale undistorted model experiments, which were performed by the Hokkaido Development Bureau (H. D. B.), Japan, to examine the tentative plan for the improvement of a low-flow channel in the Chubetsu River, which is a tributary of the Ishikari River. It is considered that the distorted model experiments to be valid with either sand or lightweight bed material. [WT5”HZ]展开更多
基金supported by the Italian Ministry of University(MIUR)call PRIN 2017 with the project“PANACEA:A technology Platform for the sustainable recovery and advanced use of NAnostructured CEllulose from Agro-food residues”(grant No.2017LEPH3M).
文摘The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.
文摘The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and development over the years in order to stay ahead of their competitors.Lightweight materials are critical in defence applications because they allow components to be lighter without sacrificing strength.This review provides an overview of the research related to defence applications.The book provides comprehensive details on current trends in the application of lightweight materials in defence.This review also includes historical and current perspectives on defence technologies.It discusses uses of lightweight materials such as metal matrix composites,polymer composites,ceramic matrix composites,fiber composites in defence sectors Finally,the review paper also emphasizes future military applications of lightweight materials.
文摘With the development of new energy vehicles, the continuous application of new materials and new technology in the automobile industry. In order to realize the requirements of energy conservation and emission reduction, new energy vehicles must be lightweight and designed, and the development of automobile lightweight materials is an important aspect of the development of automobile technology. The lightweight of the car should reduce its own weight as much as possible on the premise of protecting its own strength and safety performance. As one of the main components of the car, the lightweight effect has an important impact on the lightweight design of the vehicle. This paper introduces the common lightweight materials of the body and analyzes the application of lightweight materials for the main parts of the body, which can provide some reference for the study of lightweight design of hybrid material body.
文摘In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance of lightweight concrete.Through a mixture design approach,five formulations were selected and thoroughly characterized.The analysis of iso-response curves enabled an in-depth assessment of the cross-effects between formulation parameters and their interactions on the final properties of the material.The results show that integrating millet husks leads to a significant reduction in density,reaching up to 21%,while maintaining notable mechanical performance.A balanced formulation of sand and fibers achieved a maximum compressive strength of 12.11 MPa,demonstrating that,under specific conditions,plant fibers actively contribute to the structural integrity of the composite.In tensile strength,the positive influence of fibers is even more pronounced,with a maximum resistance of 8.62 MPa,highlighting their role in enhancing material cohesion.From a thermal perspective,millet husks reduce both thermal conductivity and effusivity,thereby limiting heat transfer and accumulation within the composite.Iso-response curve analysis reveals that these effects are directly linked to the proportions of the constituents and that achieving an optimal balance between sand,fibers,and cement is key to maximizing performance.These findings demonstrate that the adopted approach allows moving beyond conventional substitution methods by identifying optimal configurations for the design of lightweight bio-based concretes that are both strong and insulating,thereby confirming the potential of millet husks in developing lightweight concretes suitable for sustainable construction applications.
基金supported by the National Natural Science Foundation of China(Nos.U2032121,12192212,and 52325407).
文摘Damage evolution characterization and performance evaluation under realistic conditions are essential to ensure reliable operation of critical safety components.However,previous studies focus on the surface detection because of very limited penetration capacity of nondestructive testing facilities.Here,we review the recent progress of material damage mechanism by various in situ testing rigs that are compat-ible with laboratory and synchrotron radiation X-ray facilities.Then,taking metallic alloys and composites as model materials,we demonstrate the unique advantages of in situ X-ray three-dimensional tomography in unveiling complex failure mechanisms,quantifying crack growth driving forces and crack closure phenomena,and elucidating the strengthening/degrading effects from microstructure and environment on structural material degradation.Finally,we also discuss the ongoing direction of in situ multi-scale visualization and characterization with the development of advanced high-energy X-ray facilities,the improvement of in situ devices and sample environments,the demand of high-throughput tests,and the processing and application of massive test data.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3807100/2022YFB3807101)the National Natural Science Foundation of China(Nos.22205182/52203101)+4 种基金the Foundation of Aeronautics Science Fund(No.2020Z056053002)the Natural Science Basic Research Program of Shaanxi Province(No.2021JQ-224)the Fundamental Research Funds for the Central Universities(No.5000220174)the China Postdoctoral Science Foundation(No.2022M722594)supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the increased electromagnetic wave(EMW)threat to military and human health,the develop-ment of EMW-absorbing materials is crucial.Metal-organic framework derivatives containing magnetic nanoparticles and a carbon matrix are potential candidates for designing efficient EMW-absorbing mate-rials.Herein,a zeolitic imidazolate framework-67(ZIF-67)-embedded three-dimensional melamine foam is pyrolyzed to afford carbon foam-based nitrogen-doped carbon nanotube composites,named 3D foam-like CoO/Co/N-CNTs.Magnetic CoO/Co particles are confined in the dielectric carbon nanotube skeleton.The carbon nanotubes provide considerable conductive loss,while CoO/Co magnetic particles are con-ducive to providing magnetic loss and adjusting impedance matching.Moreover,the numerous defect structures introduced by heteroatomic doping(nitrogen)cause dipole polarization and simultaneously adjust impedance matching.Meanwhile,the unique porous nanotube structure promotes multiple re-flections and scattering of EMWs,further optimizing impedance matching.CoO/Co/N-CNTs composites exhibit a minimum reflection loss of−52.3 dB at a matching thickness of 2.0 mm,while the correspond-ing effective absorption bandwidth is 5.28 GHz at a matching thickness of 2.2 mm.This study reports a novel approach to fabricating a lightweight high-performance EMW-absorbing material.
基金financial support from the National Nature Science Foundation of China(51502213)
文摘To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using pyrophyl-lite, .fly ash, and Suzhou clay as the main starting materials and saw dast as the pore forming substance, and controlling the addition of the pyrophyllite （20%, 30% , and 40% by mass ） and the treating temperature （1 250, 1 300, 1 350, and 1 400 ℃ ）. The synthesized materials were characterized by the XRD, SEM and the thermal conductivity measuring in.strument. The results show at pyrophyllite addition of 30% and treat temperature of l 400 ℃ , the material can achieve linear shrinkage of 6. 6%, apparent porosity of 57%, bulk density of 0. 75 g · cm^-3, compressive strength of 2.7 MPa, and thermal conductivity at 350 ℃ of 0. 152 -0. 216 W·（ m·K）^-1.This indicates that the pyrophyllite decomposition at high temperatures forms mullite and amorphous quartz introducing volume expansion, which counteracts some shrinkage at high temperatures. So it is feasible to use pyrophyllite, fly ash waste and clay to prepare lightweight insulation refractory materials.
基金financially supported by the Young Individual Research Grants(Grant No:M22K3c0097)Singapore RIE 2025 plan and Singapore Aerospace Programme Cycle 16(Grant No:M2215a0073)led by C Tan+2 种基金supported by the Singapore A*STAR Career Development Funds(Grant No:C210812047)the National Natural Science Foundation of China(52174361 and 52374385)the support by US NSF DMR-2104933。
文摘Titanium(Ti)alloys are widely used in high-tech fields like aerospace and biomedical engineering.Laser additive manufacturing(LAM),as an innovative technology,is the key driver for the development of Ti alloys.Despite the significant advancements in LAM of Ti alloys,there remain challenges that need further research and development efforts.To recap the potential of LAM high-performance Ti alloy,this article systematically reviews LAM Ti alloys with up-to-date information on process,materials,and properties.Several feasible solutions to advance LAM Ti alloys are reviewed,including intelligent process parameters optimization,LAM process innovation with auxiliary fields and novel Ti alloys customization for LAM.The auxiliary energy fields(e.g.thermal,acoustic,mechanical deformation and magnetic fields)can affect the melt pool dynamics and solidification behaviour during LAM of Ti alloys,altering microstructures and mechanical performances.Different kinds of novel Ti alloys customized for LAM,like peritecticα-Ti,eutectoid(α+β)-Ti,hybrid(α+β)-Ti,isomorphousβ-Ti and eutecticβ-Ti alloys are reviewed in detail.Furthermore,machine learning in accelerating the LAM process optimization and new materials development is also outlooked.This review summarizes the material properties and performance envelops and benchmarks the research achievements in LAM of Ti alloys.In addition,the perspectives and further trends in LAM of Ti alloys are also highlighted.
文摘Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating refractories were prepared by the molten salt method with high silica magnesite and tertiary talc ore as raw materials by pretreating them to get light burnt magnesia and talc,and NaCl molten salt as the reaction medium.The effects of the NaCl addition,the sintering temperature,the holding time and the raw material ratio on the sample preparation were studied.The results show that when the NaCl addition is 20% of the mass of light burnt magnesia and talc mixture,the sintering temperature is 1 200 ℃,the holding time is 6 h,and m(light burnt magnesia):m(talc)=5:5,the sample has the optimal comprehensive properties:the bulk density of 1.46 g·cm^(-3) and the apparent porosity of 55.0%.In addition,it is found that self-decomposition of talc and the formation of forsterite can form pores inside the sample.
基金supported by the National Natural Science Foundation of China(Grant Nos.11932002 and 11902004).
文摘Developing lightweight lattice materials that possess exceptional strength,stiffness,and toughness(or energy absorption)simultaneously remains a significant challenge.In this study,we develop a novel design strategy:incorporating nonlocal interactions into lattice beams,creating“nonlocal lattices”.Utilizing simulation experiments,we investigated the bending behaviors of these lattices,with a particular focus on their damage evolution.Interestingly,these nonlocal lattices,categorized as stretch-dominated,exhibit extraordinary peak force(strength)and stiffness(modulus)comparable to traditional stretchdominated lattices,while maintaining superior energy absorption(toughness).Analysis of damage evolution within the lattice beams reveals a transition from localized to dispersed damage patterns.This transition delays strain localization,thereby improving material utilization efficiency.Furthermore,stronger nonlocal interaction leads to a more dispersed damage zone,further improving materials utilization efficiency.These findings demonstrate that nonlocal lattices achieve excellent energy dissipation(toughness)without compromising strength and stiffness.This highlights the crucial role of nonlocal interactions in governing strain localization within lattice materials.The design strategy here unlocks new inspirations for the development of strong and tough lightweight materials.
文摘Foamed waste glass(FWG) material is newly developed for the purpose to utilize the waste glassware and other waste glass. FWG has a multi-porous structure that consists of continuous or discontinuous voids. Hence lightweight but considerable stiffness can be achieved. In the present study, the manufacture and engineering properties of FWG are introduced first. Then, the utilizations of FWG are investigated in laboratory tests and field tests. Some case studies on design and construction work are also reported here. Through these studies we know that the discontinuous void material can be utilized as a lightweight fill material, ground improvement material and lightweight aggregate for concrete. On the other hand, the continuous void material can be used as water holding material for the greening of ground slope and rooftop, and as clarification material for water.
基金financially supported by the National Natural Science Foundation of China (No. 21875190)the National Science Fund for Distinguished Young Scholars (No. 52025034)the Analytical & Testing Center of NPU for support
文摘In this work,zeolitic imidazolate framework-8(ZIF-8)with yolk-shell and hollow structures were pre-pared by a convenient chemical etching method.A subsequent pyrolysis of ZIF-8 enabled one to pro-duce ZnO/nitrogen-doped carbon nanocomplexes with original ZIF-8 morphology,where hollow struc-ture showed superior electromagnetic wave absorption capacity and was responsible for matching the impedance of free space.The minimum reflection coefficients of hollow ZnO/nitrogen-doped carbon nanocomplexes were-51.2 dB(700℃)and-52.4 dB(800℃),respectively,whereas the effective ab-sorption band width was as large as 4 GHz and the content of pyrolyzed hollow ZIF-8 was 15 wt%,which was inferior to the level among similar electromagnetic wave(EMW)absorption materials.The conve-nient and facile strategy paves the way toward designing hierarchical structures for highly efficient and light-weight electromagnetic wave absorbers.
文摘The surface of hollow glass microspheres (HGMs) was roughened by a HCl+NH_(4)F strategy,which achieved a broken ratio as 16.10%,and then metallized by electroless plating by Co nanoparticles up to 90 wt% (abbreviated as Co-HGMs).The average grain size of Co was measured to range from 0.4 to 0.5 μm.Then Co-HGMs were mixed with liquid silicone rubber and xylene,and cured on a perspex plate applicable for flexible electromagnetic shielding.By attentive parameter optimization,a film about 0.836 mm in thickness was obtained with a density of 0.729 g/cm^(3),showing a shielding effectiveness of 15.2 dB in the X-band (8.2-12.4 GHz) at room temperature,which was ascribed to the formation of a conductive network of Co-HGMs inside the film.Simultaneously,the tensile strength of 0.89 MPa at an elongation ratio of 194.5% was also obtained,showing good mechanical properties and tensile strength.
文摘Light-weighting involves the use of advanced materials and engineering methods to enable structural elements to deliver the same,or enhanced,technical performance while using less material.The concept has been extensively explored and utilised in many industries from automotive applications to fashion and packaging and offers significant potential in the aviation sector.Typical implementations of light-weighting have involved use of high performance materials such as composites and optimisation of structures using computational aided engineering approaches with production enabled by advanced manufacturing methods such as additive manufacture,foam metals and hot forming.This paper reviews the principal approaches used in light-weighting,along with the scope for application of light-weighting in aviation applications from power-plants to airframe components.A particular area identified as warranting attention and amenable to the use of lightweighting approaches is the design of solar powered aircraft wings.The high aspect ratio typically used for these can be associated with insufficient stiffness,giving rise to non-linear deformation,aileron reversal,flutter and rigid-elastic coupling.Additional applications considered include ultralight aviation components and sub-systems,UAVs,and rockets.Advanced optimisation approaches can be applied to optimise the layout of structural elements,as well as geometrical parameters in order to maximise structural stiffness,minimise mass and enable incorporation of energy storage features.The use of additive manufacturing technologies,some capable of producing composite or multi-material components is an enabler for light-weighting,as features formally associated with one principal function can be designed to fulfil multiple functionalities。
文摘WT5”BZ]In this study, by considering the scale ratio related to the specific gravity of the submerged bed material, and introducing a degree of distortion, n the similarity laws for a distorted river model with a movable bed were derived under the conditions that the values of dual dimensionless parameters in a regime-criterion diagram for the bars are the same in a model as they are in a prototype, and that a resistance law such as the Manning-Strickler-type formula is to be valid for a model and a prototype. The usefulness of the similarity laws derived in this study was verified by comparing the bed forms from the distroted model experiments with the bed forms from the 1/50-scale undistorted model experiments, which were performed by the Hokkaido Development Bureau (H. D. B.), Japan, to examine the tentative plan for the improvement of a low-flow channel in the Chubetsu River, which is a tributary of the Ishikari River. It is considered that the distorted model experiments to be valid with either sand or lightweight bed material. [WT5”HZ]
