Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites wer...Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites were investigated by X-ray diffraction(XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and celi volumes appear as shrinkable.展开更多
Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in ...Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in heat dissipation,and reduces the risk of thermal warping,residual stress,and distortion,particularly in the fabrication of complex geometries that challenge traditional manufacturing methods.Despite the importance of support structures in AM,a systematic review covering all aspects of the design,optimisation,and removal of support structures remains lacking.This review provides an overview of various support structure types—contact and non-contact,as well as identical and dissimilar material configurations—and outlines optimisation methods,including geometric,topology,simulation-driven,data-driven,and multi-objective approaches.Additionally,the mechanisms of support removal,such as mechanical milling and chemical dissolution,and innovations like dissolvable supports and sensitised interfaces,are discussed.Future research directions are outlined,emphasising artificial intelligence(AI)-driven intelligent design,multi-material supports,sustainable support materials,support-free AM techniques,and innovative support removal methods,all of which are essential for advancing AM technology.Overall,this review aims to serve as a foundational reference for the design and optimisation of the support structure in AM.展开更多
Aqueous zinc-ion batteries(AZIBs)have emerged as a promising next-generation energy storage solution due to their high energy density,abundant resources,low cost,and high safety.However,unstable zinc anode caused by s...Aqueous zinc-ion batteries(AZIBs)have emerged as a promising next-generation energy storage solution due to their high energy density,abundant resources,low cost,and high safety.However,unstable zinc anode caused by side reactions and dendritic growth always severely worsens the long-term operation of AZIBs.Herein,a novel 3-cyclobutene sulfone(CS)additive was employed in the aqueous electrolyte to achieve a highly reversible Zn anode.The CS additive can offer strong electronegativity and high binding energy for the coordination with Zn^(2+),which enables its entry into the solvent sheath structure of Zn^(2+)and eliminates the free H_(2)O molecules from the solvated{Zn^(2+)-SO_(4)^(2-)-(H_(2)O)_(5)}.Thus,the occurrence of side reactions and dendritic growth can be effectively inhibited.Accordingly,the Zn anode achieves long cycle-life(1400 h at 1 m A cm^(-2),1 m Ah cm^(-2),and 400 h at 5 m A cm^(-2),5 m Ah cm^(-2))and high average coulombic efficiency(99.5% over 500 cycles at 10 m A cm^(-2),1 m Ah cm^(-2)).Besides,the assembled Zn||NH_(4)V_(4)O_(10)full cell suggests enhanced cycling reversibility(123.8 m Ah g^(-1)over 500 cycles at 2 A g^(-1),84.9 m Ah g^(-1)over 800 cycles at 5 A g^(-1))and improved rate capability(139.1 m Ah g^(-1)at 5 A g^(-1)).This work may exhibit the creative design and deep understanding of sulfone-based electrolyte additives for the achievement of high-performance AZIBs.展开更多
Volumetric additive manufacturing(VAM) transforms traditional 2D light pattern projection into spatial light field energy superposition,maximizing the utilization of radiated light and allowing for ultra-fast,support-...Volumetric additive manufacturing(VAM) transforms traditional 2D light pattern projection into spatial light field energy superposition,maximizing the utilization of radiated light and allowing for ultra-fast,support-free printing,which has specific applications in fields such as life sciences and optics.However,traditional VAM processes require numerous projections and extensive computational preparation,limiting practical applications due to low projection efficiency and prolonged calculation times.In this study,we developed sparse-view irradiation processing VAM(SVIP-VAM),employing an optimized odd-even(OE) irradiation strategy inspired by sparse-view computed tomography.Theoretically,we demonstrated structural contour reconstruction feasibility with as few as 8 projections.Using this sparse-view approach,we achieved high-quality fabrication with only 15 projections,enhancing each projection efficiency by over 60 times and reducing projection set computational time by nearly 10-fold.Ultimately,this efficient sparse-view method significantly expands VAM applications into fields requiring rapid manufacturing,such as tissue engineering,medical implants,and aerospace manufacturing.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of W...Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of WAAM processes,which involves intricate thermal dynamics,phase transitions,and metallurgical,mechanical,and chemical interactions,presents considerable challenges in final product qualities.Simulation technologies in WAAM have proven invaluable,providing accurate predictions in key areas such as material properties,defect identification,deposit morphology,and residual stress.These predictions play a critical role in optimising manufacturing strategies for the final product.This paper provides a comprehensive review of the simulation techniques applied in WAAM,tracing developments from 2013 to 2023.Initially,it analyses the current challenges faced by simulation methods in three main areas.Subsequently,the review explores the current modelling approaches and the applications of these simulations.Following this,the paper discusses the present state of WAAM simulation,identifying specific issues inherent to WAAM simulation itself.Finally,through a thorough review of existing literature and related analysis,the paper offers future perspectives on potential advancements in WAAM simulation strategies.展开更多
Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio o...Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio of Li/Si and the sintering temperatures on properties were discussed in terms of electrical properties and microstructures of materials.The results showed thatSrTiO 3 based varistor ceramics,with 0.6 mol% Li 2CO 3 SiO 2(Li/Si=3/2) and sintered at 1 380 ℃ in graphite and N 2 reducing atomosphere,had excellent current volatage sensing and dielectric characteristics.展开更多
Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio o...Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio of Li/Si and the sintering temperatures on properties were discussed in terms of electrical properties and microstructures of materials.The results showed thatSrTiO 3 based varistor ceramics,with 0.6 mol% Li 2CO 3 SiO 2(Li/Si=3/2) and sintered at 1 380 ℃ in graphite and N 2 reducing atomosphere,had excellent current volatage sensing and dielectric characteristics.展开更多
Additive manufacturing and 3D printing tech-nology have been developing rapidly in the last 30 years, and indicate great potential for future development. The promising future of this technology makes its impact on tr...Additive manufacturing and 3D printing tech-nology have been developing rapidly in the last 30 years, and indicate great potential for future development. The promising future of this technology makes its impact on traditional industry unpredictable. 3D printing will propel the revolution of fabrication modes forward, and bring in a new era for customized fabrication by realizing the five "any"s: use of almost any material to fabricate any part, in any quantity and any location, for any industrial field. Innovations in material, design, and fabrication processes will be inspired by the merging of 3D-printing technology and processes with traditional manufacturing processes. Finally, 3D printing will become as valuable for manufacturing industries as equivalent and subtractive manufacturing processes.展开更多
Additive manufacturing(AM),also known as three-dimensional printing,is gaining increasing attention from academia and industry due to the unique advantages it has in comparison with traditional subtractive manufacturi...Additive manufacturing(AM),also known as three-dimensional printing,is gaining increasing attention from academia and industry due to the unique advantages it has in comparison with traditional subtractive manufacturing.However,AM processing parameters are difficult to tune,since they can exert a huge impact on the printed microstructure and on the performance of the subsequent products.It is a difficult task to build a process-structure-property-performance(PSPP)relationship for AM using traditional numerical and analytical models.Today,the machine learning(ML)method has been demonstrated to be a valid way to perform complex pattern recognition and regression analysis without an explicit need to construct and solve the underlying physical models.Among ML algorithms,the neural network(NN)is the most widely used model due to the large dataset that is currently available,strong computational power,and sophisticated algorithm architecture.This paper overviews the progress of applying the NN algorithm to several aspects of the AM whole chain,including model design,in situ monitoring,and quality evaluation.Current challenges in applying NNs to AM and potential solutions for these problems are then outlined.Finally,future trends are proposed in order to provide an overall discussion of this interdisciplinary area.展开更多
Magnesium alloys remain critical in the context of light-weighting and advanced devices. The increased utilisation of magnesium(Mg)each year reveals growing demand for its Mg-based alloys. Additive manufacturing(AM) p...Magnesium alloys remain critical in the context of light-weighting and advanced devices. The increased utilisation of magnesium(Mg)each year reveals growing demand for its Mg-based alloys. Additive manufacturing(AM) provides the possibility to directly manufacture components in net-shape, providing new possibilities and applications for the use of Mg-alloys, and new prospects in the utilisation of novel physical structures made possible from ‘3D printing’. The review herein seeks to holistically explore the additive manufacturing of Mg-alloys to date, including a synopsis of processes used and properties measured(with a comparison to conventionally prepared Mg-alloys). The challenges and possibilities of AM Mg-alloys are critically elaborated for the field of mechanical metallurgy.展开更多
The study aims to demonstrate the suitability of the 3DPMD for the production of titanium components with and without reinforcing particles in layer-by-layer design. Various demonstrators are prepared and analyzed. Th...The study aims to demonstrate the suitability of the 3DPMD for the production of titanium components with and without reinforcing particles in layer-by-layer design. Various demonstrators are prepared and analyzed. The microstructure, the porosity and the hardness values of the different structures are compared with each other through metallographic cross-sections. The uniform distribution of the carbides and the interaction with the matrix was analyzed by SEM and EDX.The miller-test method(ASTM G75-07) was used to determine data for the relative abrasivity of the structures. In summary, 3DPMD offers the possibility to produce titanium structures with and without reinforced particles. Using automated routines, it is possible to generate metal structures using welding robots directly from the CAD drawings. Microstructures and properties are directly related to the process and therefore material-process-property relationships are discussed within this work.展开更多
The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.Howeve...The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.However,many void defects exist between layers in the printing process of additive manufacturing;consequently,the bonding performance between layers is poor.The bonding neck is considered a key parameter for representing the quality of interfacial bonding.In this study,the formation mechanism of the bonding neck was comprehensively analyzed.First,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was measured.Second,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was analyzed.When the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was determined.In conclusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.展开更多
In order to build a ceramic component by inkjet printing, the object must be fabricated through the interaction and solidification of drops, typically in the range of 10–100 p L. In order to achieve this goal, stable...In order to build a ceramic component by inkjet printing, the object must be fabricated through the interaction and solidification of drops, typically in the range of 10–100 p L. In order to achieve this goal, stable ceramic inks must be developed. These inks should satisfy specific rheological conditions that can be illustrated within a parameter space defined by the Reynolds and Weber numbers. Printed drops initially deform on impact with a surface by dynamic dissipative processes, but then spread to an equilibrium shape defined by capillarity. We can identify the processes by which these drops interact to form linear features during printing, but there is a poorer level of understanding as to how 2D and 3D structures form. The stability of 2D sheets of ink appears to be possible over a more limited range of process conditions that is seen with the formation of lines. In most cases, the ink solidifies through evaporation and there is a need to control the drying process to eliminate the "coffee ring" defect. Despite these uncertainties, there have been a large number of reports on the successful use of inkjet printing for the manufacture of small ceramic components from a number of different ceramics. This technique offers good prospects as a future manufacturing technique. This review identifies potential areas for future research to improve our understanding of this manufacturing method.展开更多
Additive manufacturing(AM)of ceramic matrix composites(CMCs)has enabled the production of highly customized,geometrically complex and functionalized parts with significantly improved properties and functionality,compa...Additive manufacturing(AM)of ceramic matrix composites(CMCs)has enabled the production of highly customized,geometrically complex and functionalized parts with significantly improved properties and functionality,compared to single-phase ceramic components.It also opens up a new way to shape damage-tolerant ceramic composites with co-continuous phase reinforcement inspired by natural ma-terials.Nowadays,a large variety of AM techniques has been successfully applied to fabricate CMCs,but variable properties have been obtained so far.This article provides a comprehensive review on the AM of ceramic matrix composites through a systematic evaluation of the capabilities and limitations of each AM technique,with an emphasis on reported results regarding the properties and potentials of AM man-ufactured ceramic matrix composites.展开更多
Additive manufacturing is expected to transform and upgrade the traditional foundry industry to realize the integrated manufacturing and rapid and low-cost development of high-performance components with complex shape...Additive manufacturing is expected to transform and upgrade the traditional foundry industry to realize the integrated manufacturing and rapid and low-cost development of high-performance components with complex shapes.The additive manufacturing technology commonly applied in casting mold preparation(fusible molds,sand molds/cores and ceramic cores)mainly includes selective laser sintering(SLS)and binder injection three-dimensional printing(3DP).In this work,the research status of SLS/3DP-casting processes on material preparation,equipment development,process optimization,simulation and application cases in aerospace,automotive and other fields were elaborated.Finally,the developing trends of the additive manufacturing technology in the future of foundry field are introduced,including multi-material sand molds(metal core included),ceramic core-shell integration and die-casting dies with conformal cooling runners.展开更多
By employing sintering additives of Li2CO3 and Y2O3,porous Si3N4 ceramics are prepared after experiencing the processes of sintering and post-vacuum heat treatment at 1680 and 1550°C,respectively.The experimental...By employing sintering additives of Li2CO3 and Y2O3,porous Si3N4 ceramics are prepared after experiencing the processes of sintering and post-vacuum heat treatment at 1680 and 1550°C,respectively.The experimental results demonstrate the completed phase transformation fromαtoβ-Si3N4 in Si3N4 ceramic samples with a amount of 1.60 wt%Li2CO3(0.65 wt%Li2O)and 0.33 wt%Y2O3 additives.The as-synthesized porous Si3N4 ceramics exhibit high flexural strength((126.7±2.7)MPa)and high open porosity of 50.4%at elevated temperature(1200°C).These results are attributed to the significant role of added Li2CO3 as sintering additive,where the volatilization of intergranular glassy phase occurs during sintering process.Therefore,porous Si3N4 ceramics with desired mechanical property prepared by altering the addition of sintering additives demonstrate their great potential as a promising candidate for high temperature applications.展开更多
The application of additive manufacturing technology is one of the main approaches to achieving the rapid casting.Additive manufacturing technology can directly prepare casting molds(cores)with no need of patterns,and...The application of additive manufacturing technology is one of the main approaches to achieving the rapid casting.Additive manufacturing technology can directly prepare casting molds(cores)with no need of patterns,and quickly cast complex castings.The combination of additive manufacturing and traditional casting technology can break the constraint of traditional casting technology,improve casting flexibility,and ameliorate the working environment.Besides,additive manufacturing promotes the realization of"free casting",greatly simplifying the processing procedures and shortening the manufacturing cycle.This paper summarizes the basic principle of additive manufacturing technology and its development situation domestically and overseas,mainly focusing on the development status of several main additive manufacturing technologies applicable to the foundry field,including three-dimensional printing,selective laser sintering,stereolithography,layered extrusion forming,etc.Finally,the future development trend of additive manufacturing technology in the foundry field is prospected.展开更多
Biopolymers are promising environmentally benign materials applicable in multifarious applications.They are especially favorable in implantable biomedical devices thanks to their excellent unique properties,including ...Biopolymers are promising environmentally benign materials applicable in multifarious applications.They are especially favorable in implantable biomedical devices thanks to their excellent unique properties,including bioactivity,renewability,bioresorbability,biocompatibility,biodegradability and hydrophilicity.Additive manufacturing(AM)is a flexible and intricate manufacturing technology,which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems.Three-dimensional(3D)printing of these sustainable materials is applied in functional clinical settings including wound dressing,drug delivery systems,medical implants and tissue engineering.The present review highlights recent advancements in different types of biopolymers,such as proteins and polysaccharides,which are employed to develop different biomedical products by using extrusion,vat polymerization,laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional(4D)bioprinting techniques.It also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds,and addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AMtechniques.Ideally,there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas.We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future.展开更多
Silicon carbide (SiC) ceramics have excellent properties and widely used for high temperature applications. So far, joining techniques have been applied to fabricate large SiC ceramics with complicated shapes. In this...Silicon carbide (SiC) ceramics have excellent properties and widely used for high temperature applications. So far, joining techniques have been applied to fabricate large SiC ceramics with complicated shapes. In this work, the additive manufacturing (AM) technique was examined to fabricated SiC ceramics with complicated hollow structures using the Fused Deposition Modeling (FDM) type 3D-printer. To mold the hollow structure for the applications such as heat exchangers, the “support-less” condition must be achieved. Thus, extruded SiC-phenol resin compounds must be cured immediately after molding to keep the molded shapes. To increase the thermal conductivity of the SiC compounds, the combinations of commercial SiC powders with different average diameters were examined for increasing the volume fraction of SiC particles to the phenol resin. SiC compounds with optimized rheological properties for the modified FDM-type 3D-printer were successfully obtained.展开更多
文摘Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites were investigated by X-ray diffraction(XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and celi volumes appear as shrinkable.
基金supported by the Advanced Research and Technology Innovation Centre (ARTIC)the National University of Singapore under Grant (Project Number:ADTRP1)the sponsorship of the China Scholarship Council (No. 202306130143).
文摘Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in heat dissipation,and reduces the risk of thermal warping,residual stress,and distortion,particularly in the fabrication of complex geometries that challenge traditional manufacturing methods.Despite the importance of support structures in AM,a systematic review covering all aspects of the design,optimisation,and removal of support structures remains lacking.This review provides an overview of various support structure types—contact and non-contact,as well as identical and dissimilar material configurations—and outlines optimisation methods,including geometric,topology,simulation-driven,data-driven,and multi-objective approaches.Additionally,the mechanisms of support removal,such as mechanical milling and chemical dissolution,and innovations like dissolvable supports and sensitised interfaces,are discussed.Future research directions are outlined,emphasising artificial intelligence(AI)-driven intelligent design,multi-material supports,sustainable support materials,support-free AM techniques,and innovative support removal methods,all of which are essential for advancing AM technology.Overall,this review aims to serve as a foundational reference for the design and optimisation of the support structure in AM.
基金the financial support from the Foshan Talents Special Foundation(BKBS202003)。
文摘Aqueous zinc-ion batteries(AZIBs)have emerged as a promising next-generation energy storage solution due to their high energy density,abundant resources,low cost,and high safety.However,unstable zinc anode caused by side reactions and dendritic growth always severely worsens the long-term operation of AZIBs.Herein,a novel 3-cyclobutene sulfone(CS)additive was employed in the aqueous electrolyte to achieve a highly reversible Zn anode.The CS additive can offer strong electronegativity and high binding energy for the coordination with Zn^(2+),which enables its entry into the solvent sheath structure of Zn^(2+)and eliminates the free H_(2)O molecules from the solvated{Zn^(2+)-SO_(4)^(2-)-(H_(2)O)_(5)}.Thus,the occurrence of side reactions and dendritic growth can be effectively inhibited.Accordingly,the Zn anode achieves long cycle-life(1400 h at 1 m A cm^(-2),1 m Ah cm^(-2),and 400 h at 5 m A cm^(-2),5 m Ah cm^(-2))and high average coulombic efficiency(99.5% over 500 cycles at 10 m A cm^(-2),1 m Ah cm^(-2)).Besides,the assembled Zn||NH_(4)V_(4)O_(10)full cell suggests enhanced cycling reversibility(123.8 m Ah g^(-1)over 500 cycles at 2 A g^(-1),84.9 m Ah g^(-1)over 800 cycles at 5 A g^(-1))and improved rate capability(139.1 m Ah g^(-1)at 5 A g^(-1)).This work may exhibit the creative design and deep understanding of sulfone-based electrolyte additives for the achievement of high-performance AZIBs.
基金supported financially by the Beijing Municipal Natural Science Foundation (L232109)National Natural Science Foundation of China (22073003)Fundamental Research Funds for the Central Universities (YWF-22-K-101)。
文摘Volumetric additive manufacturing(VAM) transforms traditional 2D light pattern projection into spatial light field energy superposition,maximizing the utilization of radiated light and allowing for ultra-fast,support-free printing,which has specific applications in fields such as life sciences and optics.However,traditional VAM processes require numerous projections and extensive computational preparation,limiting practical applications due to low projection efficiency and prolonged calculation times.In this study,we developed sparse-view irradiation processing VAM(SVIP-VAM),employing an optimized odd-even(OE) irradiation strategy inspired by sparse-view computed tomography.Theoretically,we demonstrated structural contour reconstruction feasibility with as few as 8 projections.Using this sparse-view approach,we achieved high-quality fabrication with only 15 projections,enhancing each projection efficiency by over 60 times and reducing projection set computational time by nearly 10-fold.Ultimately,this efficient sparse-view method significantly expands VAM applications into fields requiring rapid manufacturing,such as tissue engineering,medical implants,and aerospace manufacturing.
基金supported in part by China Scholarship Council under Grant 202208200010。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of WAAM processes,which involves intricate thermal dynamics,phase transitions,and metallurgical,mechanical,and chemical interactions,presents considerable challenges in final product qualities.Simulation technologies in WAAM have proven invaluable,providing accurate predictions in key areas such as material properties,defect identification,deposit morphology,and residual stress.These predictions play a critical role in optimising manufacturing strategies for the final product.This paper provides a comprehensive review of the simulation techniques applied in WAAM,tracing developments from 2013 to 2023.Initially,it analyses the current challenges faced by simulation methods in three main areas.Subsequently,the review explores the current modelling approaches and the applications of these simulations.Following this,the paper discusses the present state of WAAM simulation,identifying specific issues inherent to WAAM simulation itself.Finally,through a thorough review of existing literature and related analysis,the paper offers future perspectives on potential advancements in WAAM simulation strategies.
文摘Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio of Li/Si and the sintering temperatures on properties were discussed in terms of electrical properties and microstructures of materials.The results showed thatSrTiO 3 based varistor ceramics,with 0.6 mol% Li 2CO 3 SiO 2(Li/Si=3/2) and sintered at 1 380 ℃ in graphite and N 2 reducing atomosphere,had excellent current volatage sensing and dielectric characteristics.
文摘Semiconducting SrTiO 3 based voltage sensing and dielectric ceramics were prepared by single step sintering with Li 2CO 3 SiO 2 as liquid phase additives.The effects of the content of liquid phase,the ratio of Li/Si and the sintering temperatures on properties were discussed in terms of electrical properties and microstructures of materials.The results showed thatSrTiO 3 based varistor ceramics,with 0.6 mol% Li 2CO 3 SiO 2(Li/Si=3/2) and sintered at 1 380 ℃ in graphite and N 2 reducing atomosphere,had excellent current volatage sensing and dielectric characteristics.
文摘Additive manufacturing and 3D printing tech-nology have been developing rapidly in the last 30 years, and indicate great potential for future development. The promising future of this technology makes its impact on traditional industry unpredictable. 3D printing will propel the revolution of fabrication modes forward, and bring in a new era for customized fabrication by realizing the five "any"s: use of almost any material to fabricate any part, in any quantity and any location, for any industrial field. Innovations in material, design, and fabrication processes will be inspired by the merging of 3D-printing technology and processes with traditional manufacturing processes. Finally, 3D printing will become as valuable for manufacturing industries as equivalent and subtractive manufacturing processes.
文摘Additive manufacturing(AM),also known as three-dimensional printing,is gaining increasing attention from academia and industry due to the unique advantages it has in comparison with traditional subtractive manufacturing.However,AM processing parameters are difficult to tune,since they can exert a huge impact on the printed microstructure and on the performance of the subsequent products.It is a difficult task to build a process-structure-property-performance(PSPP)relationship for AM using traditional numerical and analytical models.Today,the machine learning(ML)method has been demonstrated to be a valid way to perform complex pattern recognition and regression analysis without an explicit need to construct and solve the underlying physical models.Among ML algorithms,the neural network(NN)is the most widely used model due to the large dataset that is currently available,strong computational power,and sophisticated algorithm architecture.This paper overviews the progress of applying the NN algorithm to several aspects of the AM whole chain,including model design,in situ monitoring,and quality evaluation.Current challenges in applying NNs to AM and potential solutions for these problems are then outlined.Finally,future trends are proposed in order to provide an overall discussion of this interdisciplinary area.
基金support from Australian National University Futures Schemethe support from the first Singapore-Germany Academic-Industry (2 + 2) international collaboration grant (Grant No.: A1890b0050)。
文摘Magnesium alloys remain critical in the context of light-weighting and advanced devices. The increased utilisation of magnesium(Mg)each year reveals growing demand for its Mg-based alloys. Additive manufacturing(AM) provides the possibility to directly manufacture components in net-shape, providing new possibilities and applications for the use of Mg-alloys, and new prospects in the utilisation of novel physical structures made possible from ‘3D printing’. The review herein seeks to holistically explore the additive manufacturing of Mg-alloys to date, including a synopsis of processes used and properties measured(with a comparison to conventionally prepared Mg-alloys). The challenges and possibilities of AM Mg-alloys are critically elaborated for the field of mechanical metallurgy.
文摘The study aims to demonstrate the suitability of the 3DPMD for the production of titanium components with and without reinforcing particles in layer-by-layer design. Various demonstrators are prepared and analyzed. The microstructure, the porosity and the hardness values of the different structures are compared with each other through metallographic cross-sections. The uniform distribution of the carbides and the interaction with the matrix was analyzed by SEM and EDX.The miller-test method(ASTM G75-07) was used to determine data for the relative abrasivity of the structures. In summary, 3DPMD offers the possibility to produce titanium structures with and without reinforced particles. Using automated routines, it is possible to generate metal structures using welding robots directly from the CAD drawings. Microstructures and properties are directly related to the process and therefore material-process-property relationships are discussed within this work.
基金Supported by National Key R&D Program of China(Grant No.2017YFB1103400).
文摘The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.However,many void defects exist between layers in the printing process of additive manufacturing;consequently,the bonding performance between layers is poor.The bonding neck is considered a key parameter for representing the quality of interfacial bonding.In this study,the formation mechanism of the bonding neck was comprehensively analyzed.First,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was measured.Second,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was analyzed.When the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was determined.In conclusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.
文摘In order to build a ceramic component by inkjet printing, the object must be fabricated through the interaction and solidification of drops, typically in the range of 10–100 p L. In order to achieve this goal, stable ceramic inks must be developed. These inks should satisfy specific rheological conditions that can be illustrated within a parameter space defined by the Reynolds and Weber numbers. Printed drops initially deform on impact with a surface by dynamic dissipative processes, but then spread to an equilibrium shape defined by capillarity. We can identify the processes by which these drops interact to form linear features during printing, but there is a poorer level of understanding as to how 2D and 3D structures form. The stability of 2D sheets of ink appears to be possible over a more limited range of process conditions that is seen with the formation of lines. In most cases, the ink solidifies through evaporation and there is a need to control the drying process to eliminate the "coffee ring" defect. Despite these uncertainties, there have been a large number of reports on the successful use of inkjet printing for the manufacture of small ceramic components from a number of different ceramics. This technique offers good prospects as a future manufacturing technique. This review identifies potential areas for future research to improve our understanding of this manufacturing method.
基金This work was supported by Shenzhen Science and Technology Innovation Commission(Nos.KQTD20190929172505711,20200925155544005)The author(Ji Zou)gratefully acknowledges the support from the National Natural Science Foundation of China(No.52022072)This work was also supported by Shenzhen International Collaboration Programme(No.GJHZ20200731095606021).The authors acknowledge the assistance of SUSTech Core Research Facilities.
文摘Additive manufacturing(AM)of ceramic matrix composites(CMCs)has enabled the production of highly customized,geometrically complex and functionalized parts with significantly improved properties and functionality,compared to single-phase ceramic components.It also opens up a new way to shape damage-tolerant ceramic composites with co-continuous phase reinforcement inspired by natural ma-terials.Nowadays,a large variety of AM techniques has been successfully applied to fabricate CMCs,but variable properties have been obtained so far.This article provides a comprehensive review on the AM of ceramic matrix composites through a systematic evaluation of the capabilities and limitations of each AM technique,with an emphasis on reported results regarding the properties and potentials of AM man-ufactured ceramic matrix composites.
基金the Principle and Method of Integrated Laser 3D Printing of Metal Core-Variable Area Performance Complex Sand Mold(Grant No.U1808216)the Aero Engine and Gas Turbine Major Special Fundamental Research Fund Project(2017-Ⅶ-0008-0102)。
文摘Additive manufacturing is expected to transform and upgrade the traditional foundry industry to realize the integrated manufacturing and rapid and low-cost development of high-performance components with complex shapes.The additive manufacturing technology commonly applied in casting mold preparation(fusible molds,sand molds/cores and ceramic cores)mainly includes selective laser sintering(SLS)and binder injection three-dimensional printing(3DP).In this work,the research status of SLS/3DP-casting processes on material preparation,equipment development,process optimization,simulation and application cases in aerospace,automotive and other fields were elaborated.Finally,the developing trends of the additive manufacturing technology in the future of foundry field are introduced,including multi-material sand molds(metal core included),ceramic core-shell integration and die-casting dies with conformal cooling runners.
基金Project(202045007)supported by the Start-up Funds for Outstanding Talents in Central South University,China。
文摘By employing sintering additives of Li2CO3 and Y2O3,porous Si3N4 ceramics are prepared after experiencing the processes of sintering and post-vacuum heat treatment at 1680 and 1550°C,respectively.The experimental results demonstrate the completed phase transformation fromαtoβ-Si3N4 in Si3N4 ceramic samples with a amount of 1.60 wt%Li2CO3(0.65 wt%Li2O)and 0.33 wt%Y2O3 additives.The as-synthesized porous Si3N4 ceramics exhibit high flexural strength((126.7±2.7)MPa)and high open porosity of 50.4%at elevated temperature(1200°C).These results are attributed to the significant role of added Li2CO3 as sintering additive,where the volatilization of intergranular glassy phase occurs during sintering process.Therefore,porous Si3N4 ceramics with desired mechanical property prepared by altering the addition of sintering additives demonstrate their great potential as a promising candidate for high temperature applications.
基金the National Natural Science Foundation of China(Grant Nos.59635040,51775204,51375190)the National Key R&D Program of China(Grant Nos.2020YFB2008300,2020YFB2008304)。
文摘The application of additive manufacturing technology is one of the main approaches to achieving the rapid casting.Additive manufacturing technology can directly prepare casting molds(cores)with no need of patterns,and quickly cast complex castings.The combination of additive manufacturing and traditional casting technology can break the constraint of traditional casting technology,improve casting flexibility,and ameliorate the working environment.Besides,additive manufacturing promotes the realization of"free casting",greatly simplifying the processing procedures and shortening the manufacturing cycle.This paper summarizes the basic principle of additive manufacturing technology and its development situation domestically and overseas,mainly focusing on the development status of several main additive manufacturing technologies applicable to the foundry field,including three-dimensional printing,selective laser sintering,stereolithography,layered extrusion forming,etc.Finally,the future development trend of additive manufacturing technology in the foundry field is prospected.
文摘Biopolymers are promising environmentally benign materials applicable in multifarious applications.They are especially favorable in implantable biomedical devices thanks to their excellent unique properties,including bioactivity,renewability,bioresorbability,biocompatibility,biodegradability and hydrophilicity.Additive manufacturing(AM)is a flexible and intricate manufacturing technology,which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems.Three-dimensional(3D)printing of these sustainable materials is applied in functional clinical settings including wound dressing,drug delivery systems,medical implants and tissue engineering.The present review highlights recent advancements in different types of biopolymers,such as proteins and polysaccharides,which are employed to develop different biomedical products by using extrusion,vat polymerization,laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional(4D)bioprinting techniques.It also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds,and addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AMtechniques.Ideally,there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas.We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future.
文摘Silicon carbide (SiC) ceramics have excellent properties and widely used for high temperature applications. So far, joining techniques have been applied to fabricate large SiC ceramics with complicated shapes. In this work, the additive manufacturing (AM) technique was examined to fabricated SiC ceramics with complicated hollow structures using the Fused Deposition Modeling (FDM) type 3D-printer. To mold the hollow structure for the applications such as heat exchangers, the “support-less” condition must be achieved. Thus, extruded SiC-phenol resin compounds must be cured immediately after molding to keep the molded shapes. To increase the thermal conductivity of the SiC compounds, the combinations of commercial SiC powders with different average diameters were examined for increasing the volume fraction of SiC particles to the phenol resin. SiC compounds with optimized rheological properties for the modified FDM-type 3D-printer were successfully obtained.
