Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadr...Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.展开更多
Additive manufacturing technology is highly regarded due to its advantages,such as high precision and the ability to address complex geometric challenges.However,the development of additive manufacturing process is co...Additive manufacturing technology is highly regarded due to its advantages,such as high precision and the ability to address complex geometric challenges.However,the development of additive manufacturing process is constrained by issues like unclear fundamental principles,complex experimental cycles,and high costs.Machine learning,as a novel artificial intelligence technology,has the potential to deeply engage in the development of additive manufacturing process,assisting engineers in learning and developing new techniques.This paper provides a comprehensive overview of the research and applications of machine learning in the field of additive manufacturing,particularly in model design and process development.Firstly,it introduces the background and significance of machine learning-assisted design in additive manufacturing process.It then further delves into the application of machine learning in additive manufacturing,focusing on model design and process guidance.Finally,it concludes by summarizing and forecasting the development trends of machine learning technology in the field of additive manufacturing.展开更多
As a subversive manufacturing technology, additive manufacturing technology has many technical advantages such as high freedom of design and not limited by complex structure of parts. The application of additive manuf...As a subversive manufacturing technology, additive manufacturing technology has many technical advantages such as high freedom of design and not limited by complex structure of parts. The application of additive manufacturing technology to the charge molding of energetic materials will subvert the traditional manufacturing concept of energetic materials, realize the advanced charge design concept, shorten the research and development time of weapons and equipment, and improve the comprehensive performance of weapons and equipment, which is of great significance for the rapid development of high-tech weapons and equipment. This paper analyzes the research progress of additive manufacturing technology in the field of energetic materials at home and abroad and puts forward some suggestions for future research of this technology. .展开更多
Thermal analysis plays a key role in the online inspection of molten iron quality.Different solidification process of molten iron can be reflected by thermal analysis curves,and silicon is one of important elements af...Thermal analysis plays a key role in the online inspection of molten iron quality.Different solidification process of molten iron can be reflected by thermal analysis curves,and silicon is one of important elements affecting the solidification of molten iron.In this study,FeSi75 was added in one chamber of the dual-chamber sample cup,and the influences of FeSi75 additive on the characteristic values of thermal analysis curves and vermiculating rate were investigated.The results show that with the increase of FeSi75,the start temperature of austenite formation TALfirstly decreases and then increases,but the start temperature of eutectic growth TSEF,the lowest eutectic temperature TEU,temperature at maximum eutectic reaction rate TEM,and highest eutectic temperature TERkeep always an increase.The temperature at final solidification point TEShas little change.The FeSi75 additive has different influences on the vermiculating rate of molten iron with different vermiculation,and the vermiculating rate increases for lower vermiculation molten iron while decreases for higher one.According to the thermal analysis curves obtained by a dual-chamber sample cup with 0.30wt.%FeSi75 additive in one chamber,the vermiculating rate of molten iron can be evaluated by comparing the characteristic values of these curves.The time differenceΔtERcorresponding to the highest eutectic temperature TERhas a closer relationship with the vermiculating rate,and a parabolic regression curve between the time differenceΔtERand vermiculating rateηhas been obtained within the range of 65%to 95%,which is suitable for the qualified melt.展开更多
Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode ...Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode limit their commercialization.These problems can be tackled through the optimization of the electrolyte.However,the screening of electrolyte additives using normal electrochemical methods is time-consuming and labor-intensive.Herein,a fast and simple method based on the digital holography is developed.It can realize the in situ monitoring of electrode/electrolyte interface and provide direct information concerning ion concentration evolution of the diffusion layer.It is effective and time-saving in estimating the homogeneity of the deposition layer and predicting the tendency of dendrite growth,thus able to value the applicability of electrolyte additives.The feasibility of this method is further validated by the forecast and evaluation of thioacetamide additive.Based on systematic characterization,it is proved that the introduction of thioacetamide can not only regulate the interficial ion flux to induce dendrite-free Zn deposition,but also construct adsorption molecule layers to inhibit side reactions of Zn anode.Being easy to operate,capable of in situ observation,and able to endure harsh conditions,digital holography method will be a promising approach for the interfacial investigation of other battery systems.展开更多
Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the ...Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the precision of molded parts.In this study,the discrete element method(DEM)was adopted to simulate the powder spreading process with a roller.The three powder bed quality indicators,including the molding layer offset,voidage fraction,and surface roughness,were established.Besides,the influence of the three process parameters,which are roller’s translational speed,rotational speed,and powder spreading layer thickness on the powder bed quality indicators was also analyzed.The results show that with the reduction of the powder spreading layer thickness and the increase of the rotational speed,the offset increased significantly;when the translational speed increased,the offset first increased and then decreased,which resulted in an extreme value;with the increase of the layer thickness and the decrease of the translational speed,the values for voidage fraction and surface roughness significantly reduced.The powder bed quality indicators were adopted as the optimization objective,and the multi-objective parameter optimization was carried out.The predicted optimal powder spreading parameters and powder bed quality indicators were then obtained.Moreover,the optimal values were then verified.This study can provide informative guidance for in-situ manufacturing at the moon in future deep space exploration missions.展开更多
Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufac...Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.展开更多
The magnesium matrix composites(MMCs) formed by introducing reinforcements to magnesium alloys overcome the limitations of the mechanical properties to a certain extent, presenting unique and excellent properties that...The magnesium matrix composites(MMCs) formed by introducing reinforcements to magnesium alloys overcome the limitations of the mechanical properties to a certain extent, presenting unique and excellent properties that any component does not have, such as high specific stiffness and specific strength, good dimensional stability, outstanding shock absorption performance, excellent electromagnetic shielding and hydrogen storage characteristics, etc. As an emerging manufacturing technology, additive manufacturing(AM) is based on the design of threedimensional(3D) data model to obtain 3D objects through layer-by-layer processing, which possesses the advantages of short manufacturing cycle, high material utilization rate, high degree of design freedom, excellent mechanical properties and the ability to fabricate complex structural components. Combining the high stiffness and high strength properties of MMCs and the technical advantages of AM forming complex structural parts with high performance, the prepared AM MMCs have huge potential advantages and broad application prospects in new high-tech industries such as automobile, aerospace, consumer electronics and biomedicine, etc. This paper reviews the research progress in the field of AM MMCs, mainly introduces the main AM technologies, including selective laser melting(SLM), electron beam selective melting(EBSM), laser engineered net shaping(LENS) and wire and arc additive manufacturing(WAAM). The formation mechanism and control methods of the typical defects including balling effect, porosity, poor fusion, loss of alloy elements and cracks produced during AM are discussed. The main challenges of AM MMCs are proposed from the aspects of composition design and the preparation of powder raw material. The relationship between the microstructure and mechanical properties, corrosion performance and biocompatibility of AM MMCs are elaborated in detail. The application potential of AM MMCs in various fields at present and in the future is introduced. Finally, the development direction and urgent problems to be solved in the AM MMCs are prospected.展开更多
Metal additive manufacturing(MAM)is an emerging and disruptive technology that builds three-dimensional(3D)components by adding layer-upon-layer of metallic materials.The complex cyclic thermal history and highly loca...Metal additive manufacturing(MAM)is an emerging and disruptive technology that builds three-dimensional(3D)components by adding layer-upon-layer of metallic materials.The complex cyclic thermal history and highly localized energy can produce large temperature gradients,which will,in turn,lead to compressive and tensile stress during the MAM process and eventually result in residual stress.Being an issue of great concern,residual stress,which can cause distortion,delamination,cracking,etc.,is considered a key mechanical quantity that affects the manufacturing quality and service performance of MAM parts.In this review paper,the ongoing work in the field of residual stress determination and control for MAM is described with a particular emphasis on the experimental measurement/control methods and numerical models.We also provide insight on what still requires to be achieved and the research opportunities and challenges.展开更多
Laser powder bed fusion(LPBF)makes it possible for biodegradable zinc(Zn)to be used to produce customized orthopedic implants.In this research,we investigate the impact of laser power and scanning speed on the develop...Laser powder bed fusion(LPBF)makes it possible for biodegradable zinc(Zn)to be used to produce customized orthopedic implants.In this research,we investigate the impact of laser power and scanning speed on the development of surface quality,relative densification,and texture during LPBF of Zn implants.Increasing laser power was able to decrease melt viscosity and surface tension,which improved the metallurgical bonding between adjacent tracks.Uneven and twisted tracks also became continuous and straight.Scanning speed could controlmolten-pool temperature to restrain grain natural orientation,achieving various crystal orientations and a weakened texture.Importantly,it further avoided the thermal expansion and contraction caused by excessive energy storage and accumulation in the matrix,thus reducing the generation of high-dislocation density.As a result,by selecting a reasonable laser power and scanning speed,the LPBF parts exhibited a flat surface morphology and a high density over 99.5%.Their average hardness,mechanical strength,and elongation reached 50.2 HV,127.8 MPa,and 7.6%,respectively.Additionally,the parts displayed a moderate degradation rate and excellent osteogenic properties.All these results provide a basis for selecting process parameters to optimize the comprehensive properties of LPBF-processed Zn parts for biodegradable applications.展开更多
The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in hig...The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems.However,the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states,inevitably leading to severe metallurgical defects in Ni-based superalloys.Cracks are the greatest threat to these materials’integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure.Consequently,there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking,as this knowledge will enable the wider application of these unique materials.To this end,this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM.In addition,several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.展开更多
Additive manufacturing(AM)technology makes parts through layer-by-layer deposition,which can regulate the microstructure and properties of different parts of a single part well.It provides a new idea for the preparati...Additive manufacturing(AM)technology makes parts through layer-by-layer deposition,which can regulate the microstructure and properties of different parts of a single part well.It provides a new idea for the preparation of functionally gradient materials(FGM),and has become a research hotspot at present.By referring to and analyzing the recent research achievements in the additive manufacturing tech-nology of FGM,the latest research progress at domestic and abroad from four aspects were summaried:selective laser melting additive man-ufacturing,electron beam additive manufacturing,arc additive manufacturing,path planning,and material texture.Moreover,the existing problems in the research are pointed out,and the future research direction and focus are prospected.展开更多
Additive manufacturing (AM) technology such as selective laser melting (SLM) often produces a high refection phenomenon that makes defect detection and information extraction challenging. Meanwhile, it is essential to...Additive manufacturing (AM) technology such as selective laser melting (SLM) often produces a high refection phenomenon that makes defect detection and information extraction challenging. Meanwhile, it is essential to establish a characterization method for defect analysis to provide sufcient information for process diagnosis and optimization. However, there is still a lack of universal standards for the characterization of defects in SLM parts. In this study, a polarization-based imaging system was proposed, and a set of characterization parameters for SLM defects was established. The contrast, defect contour information, and high refection suppression efect of the SLM part defects were analyzed. Comparative analysis was conducted on defect characterization parameters, including geometric and texture parameters. The experimental results demonstrated the efects of the polarization imaging system and verifed the feasibility of the defect feature extraction and characterization method. The research work provides an efective solution for defect detection and helps to establish a universal standard for defect characterization in additive manufacturing.展开更多
In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidati...In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon atmosphere.Compression tests were performed on as sintered parts.Additionally,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental results.The experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.展开更多
A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy was designed using the cluster formula approach(cluster-plus-glue-atom model)and prepared by laser melting deposition(LMD).Its composition formula 12[Al-Ti_(12...A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy was designed using the cluster formula approach(cluster-plus-glue-atom model)and prepared by laser melting deposition(LMD).Its composition formula 12[Al-Ti_(12)](AlTi_(2))+5[Al_(0.8)Si_(0.2)-Ti_(12)Zr_(2)](V_(0.8)Mo_(0.2)Nb_(1)Ti)features an enhancedβ-Ti via co-alloying of Zr,V,Mo,Nb and Si.The experimental results show that the cluster formula ofαandβphases in the novel alloy are respectivelyα-[Al-Ti_(11.5)Zr_(0.5)](Al_(1)Ti_(2))andβ-[Al_(0.8)Si_(0.2)-Ti_(13.2)Zr_(0.8)](V_(1)Mo_(0.4)Nb_(1.6)),both containing Zr elements.The fitted composition via the α andβphase cluster formulas has little difference with the actual alloy composition,suggesting that the validity of cluster-plus-glue-atom model in the alloy composition design.After hot isostatic pressing(HIP),both the Ti-6Al-4V and the novel alloy by LMD are characterized by prior-βcolumnar grains,while the typical<100>texture disappears.Compared with Ti-6Al-4V,Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy exhibits a combination of higher strength(1,056 MPa)and higher ductility(14%)at room temperature and higher strength(580 MPa)at 550℃ after HIP,and can potentially serves as LMD materials.展开更多
As a new type of lightweight structure,metallic lattice structure has higher stiffness and strength to weight ratio.To freely obtain 316L lattice structures with designed cell structure and adjustable porosity,additiv...As a new type of lightweight structure,metallic lattice structure has higher stiffness and strength to weight ratio.To freely obtain 316L lattice structures with designed cell structure and adjustable porosity,additive manufacturing combined with investment casting was conducted to fabricate the 316L lattice structures with Kelvin cell.The compression simulation of 316L lattice structures with different porosities was carried out by using the finite element method.The numerical simulation results were verified by compression experiment,and the simulated results were consistent with the compression tests.The compressive mechanical properties of 316L lattice structures are directly related to porosity and independent of strut diameters.The 316L lattice structures with Kelvin cell have a smooth stress-strain curve and obvious plastic platform,and the hump stress-strain curves are avoided.展开更多
Multifunctional structures(MFSs)integrate diverse functions to achieve superior properties.However,conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equi...Multifunctional structures(MFSs)integrate diverse functions to achieve superior properties.However,conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equipment with multiple stations to achieve the integration of distinct materials and devices—are unable to satisfy the requirements of MFS applications in emerging industries such as aerospace engineering.Motivated by the concept of design for manufacturing,we adopt a layer regulation method with an established optimization model to design typical MFSs with load-bearing,electric,heat-conduction,and radiation-shielding functions.A high-temperature in situ additive manufacturing(AM)technology is developed to print various metallic wires or carbon fiber-reinforced high-meltingpoint polyetheretherketone(PEEK)composites.It is found that the MFS,despite its low mass,exceeds the stiffness of the PEEK substrate by 21.5%.The embedded electrics remain functional after the elastic deformation stage.Compared with those of the PEEK substrate,the equivalent thermal conductivity of the MFS beneath the central heat source area is enhanced by 568.0%,and the radiation shielding is improved by 27.9%.Moreover,a satellite prototype with diverse MFSs is rapidly constructed as an illustration.This work provides a systematic approach for high-performance design and advanced manufacturing,which exhibits considerable prospects for both the function expansion and performance enhancement of industrial equipment.展开更多
We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After ...We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.展开更多
Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degr...Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degradation. In this work, mesoporous bioglass(MBG)with high pore volume(0.59 cc/g) and huge specific surface area(110.78 m^(2)/g) was synthesized using improved sol-gel method, and introduced into Mg-based composite via laser additive manufacturing. Immersion tests showed that the incorporated MBG served as powerful adsorption sites, which promoted the in-situ deposition of apatite by successively adsorbing Ca2+and HPO42-. Such dense apatite film acted as an efficient protection layer and enhanced the corrosion resistance of Mg matrix, which was proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg based composite showed a significantly decreased degradation rate of 0.31 mm/year. Furthermore,MBG also improved the mechanical properties as well as cell behavior. This work highlighted the advantages of MBG in the fabrication of Mg-based implant with enhanced overall performance for orthopedic application.展开更多
Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusio...Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.展开更多
基金The work is supported by the National Natural Science Foundation of China(Nos.U21A20124 and 52205059)the Key Research and Development Program of Zhejiang Province(No.2022C01039)。
文摘Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.
基金financially supported by the Technology Development Fund of China Academy of Machinery Science and Technology(No.170221ZY01)。
文摘Additive manufacturing technology is highly regarded due to its advantages,such as high precision and the ability to address complex geometric challenges.However,the development of additive manufacturing process is constrained by issues like unclear fundamental principles,complex experimental cycles,and high costs.Machine learning,as a novel artificial intelligence technology,has the potential to deeply engage in the development of additive manufacturing process,assisting engineers in learning and developing new techniques.This paper provides a comprehensive overview of the research and applications of machine learning in the field of additive manufacturing,particularly in model design and process development.Firstly,it introduces the background and significance of machine learning-assisted design in additive manufacturing process.It then further delves into the application of machine learning in additive manufacturing,focusing on model design and process guidance.Finally,it concludes by summarizing and forecasting the development trends of machine learning technology in the field of additive manufacturing.
文摘As a subversive manufacturing technology, additive manufacturing technology has many technical advantages such as high freedom of design and not limited by complex structure of parts. The application of additive manufacturing technology to the charge molding of energetic materials will subvert the traditional manufacturing concept of energetic materials, realize the advanced charge design concept, shorten the research and development time of weapons and equipment, and improve the comprehensive performance of weapons and equipment, which is of great significance for the rapid development of high-tech weapons and equipment. This paper analyzes the research progress of additive manufacturing technology in the field of energetic materials at home and abroad and puts forward some suggestions for future research of this technology. .
基金the financial support of the State Key Laboratory of Engine Reliability(skler-202105)。
文摘Thermal analysis plays a key role in the online inspection of molten iron quality.Different solidification process of molten iron can be reflected by thermal analysis curves,and silicon is one of important elements affecting the solidification of molten iron.In this study,FeSi75 was added in one chamber of the dual-chamber sample cup,and the influences of FeSi75 additive on the characteristic values of thermal analysis curves and vermiculating rate were investigated.The results show that with the increase of FeSi75,the start temperature of austenite formation TALfirstly decreases and then increases,but the start temperature of eutectic growth TSEF,the lowest eutectic temperature TEU,temperature at maximum eutectic reaction rate TEM,and highest eutectic temperature TERkeep always an increase.The temperature at final solidification point TEShas little change.The FeSi75 additive has different influences on the vermiculating rate of molten iron with different vermiculation,and the vermiculating rate increases for lower vermiculation molten iron while decreases for higher one.According to the thermal analysis curves obtained by a dual-chamber sample cup with 0.30wt.%FeSi75 additive in one chamber,the vermiculating rate of molten iron can be evaluated by comparing the characteristic values of these curves.The time differenceΔtERcorresponding to the highest eutectic temperature TERhas a closer relationship with the vermiculating rate,and a parabolic regression curve between the time differenceΔtERand vermiculating rateηhas been obtained within the range of 65%to 95%,which is suitable for the qualified melt.
基金supported by the National Natural Science Foundation of China(No.22075115)Natural Science Foundation of Jiangsu Province(No.BK20211352)+2 种基金Joint Funds of the National Natural Science Foundation of China(No.U2141201)Natural Science Foundation(No.22KJA430005)of Jiangsu Education Committee of ChinaPostgraduate Research and Practice Innovation Program of Jiangsu Normal University(No.2021XKT0296).
文摘Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode limit their commercialization.These problems can be tackled through the optimization of the electrolyte.However,the screening of electrolyte additives using normal electrochemical methods is time-consuming and labor-intensive.Herein,a fast and simple method based on the digital holography is developed.It can realize the in situ monitoring of electrode/electrolyte interface and provide direct information concerning ion concentration evolution of the diffusion layer.It is effective and time-saving in estimating the homogeneity of the deposition layer and predicting the tendency of dendrite growth,thus able to value the applicability of electrolyte additives.The feasibility of this method is further validated by the forecast and evaluation of thioacetamide additive.Based on systematic characterization,it is proved that the introduction of thioacetamide can not only regulate the interficial ion flux to induce dendrite-free Zn deposition,but also construct adsorption molecule layers to inhibit side reactions of Zn anode.Being easy to operate,capable of in situ observation,and able to endure harsh conditions,digital holography method will be a promising approach for the interfacial investigation of other battery systems.
文摘Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the precision of molded parts.In this study,the discrete element method(DEM)was adopted to simulate the powder spreading process with a roller.The three powder bed quality indicators,including the molding layer offset,voidage fraction,and surface roughness,were established.Besides,the influence of the three process parameters,which are roller’s translational speed,rotational speed,and powder spreading layer thickness on the powder bed quality indicators was also analyzed.The results show that with the reduction of the powder spreading layer thickness and the increase of the rotational speed,the offset increased significantly;when the translational speed increased,the offset first increased and then decreased,which resulted in an extreme value;with the increase of the layer thickness and the decrease of the translational speed,the values for voidage fraction and surface roughness significantly reduced.The powder bed quality indicators were adopted as the optimization objective,and the multi-objective parameter optimization was carried out.The predicted optimal powder spreading parameters and powder bed quality indicators were then obtained.Moreover,the optimal values were then verified.This study can provide informative guidance for in-situ manufacturing at the moon in future deep space exploration missions.
基金the financial support by National Key Research and Development Project(Grand No.2020YFC1107202)Guangdong Basic and Applied Basic Research Foundation(Grand No.2020A1515110754)+3 种基金MOE Key Lab of Disaster Forest and Control in Engineering,Jinan University(Grand No.20200904008)Educational Commission of Guangdong Province(Grand No.2020KTSCX012)the Fundamental Research Funds for Central Universities(Grand No.21620342)the support from National Natural Science Foundation of China,NSFC(Grand No.51775556)。
文摘Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.
基金financially supported by the Defense Industrial Technology Development Program (no.JCKY2021601B203)Ningbo Yongjiang Talent Project (no.YJ0222012)Ningbo Beilun District “Strong Port and Strong District Talent Introduction” Project (no.QG0222002)。
文摘The magnesium matrix composites(MMCs) formed by introducing reinforcements to magnesium alloys overcome the limitations of the mechanical properties to a certain extent, presenting unique and excellent properties that any component does not have, such as high specific stiffness and specific strength, good dimensional stability, outstanding shock absorption performance, excellent electromagnetic shielding and hydrogen storage characteristics, etc. As an emerging manufacturing technology, additive manufacturing(AM) is based on the design of threedimensional(3D) data model to obtain 3D objects through layer-by-layer processing, which possesses the advantages of short manufacturing cycle, high material utilization rate, high degree of design freedom, excellent mechanical properties and the ability to fabricate complex structural components. Combining the high stiffness and high strength properties of MMCs and the technical advantages of AM forming complex structural parts with high performance, the prepared AM MMCs have huge potential advantages and broad application prospects in new high-tech industries such as automobile, aerospace, consumer electronics and biomedicine, etc. This paper reviews the research progress in the field of AM MMCs, mainly introduces the main AM technologies, including selective laser melting(SLM), electron beam selective melting(EBSM), laser engineered net shaping(LENS) and wire and arc additive manufacturing(WAAM). The formation mechanism and control methods of the typical defects including balling effect, porosity, poor fusion, loss of alloy elements and cracks produced during AM are discussed. The main challenges of AM MMCs are proposed from the aspects of composition design and the preparation of powder raw material. The relationship between the microstructure and mechanical properties, corrosion performance and biocompatibility of AM MMCs are elaborated in detail. The application potential of AM MMCs in various fields at present and in the future is introduced. Finally, the development direction and urgent problems to be solved in the AM MMCs are prospected.
基金financially supported by the National Natural Science Foundation of China(12032013,12272131)the Provincial Natural Science Foundation of Hunan(2022JJ40029)the Scientific Research Foundation of Hunan Provincial Education Department(21C0087)。
文摘Metal additive manufacturing(MAM)is an emerging and disruptive technology that builds three-dimensional(3D)components by adding layer-upon-layer of metallic materials.The complex cyclic thermal history and highly localized energy can produce large temperature gradients,which will,in turn,lead to compressive and tensile stress during the MAM process and eventually result in residual stress.Being an issue of great concern,residual stress,which can cause distortion,delamination,cracking,etc.,is considered a key mechanical quantity that affects the manufacturing quality and service performance of MAM parts.In this review paper,the ongoing work in the field of residual stress determination and control for MAM is described with a particular emphasis on the experimental measurement/control methods and numerical models.We also provide insight on what still requires to be achieved and the research opportunities and challenges.
基金The National Natural Science Foundation of China(Nos.51935014,52165043,52105352,and 82072084)Jiangxi Provincial Natural Science Foundation of China(No.20212BAB214026)+1 种基金The Project of State Key Laboratory of High Performance Complex ManufacturingThe Project of Science and Technology of Jiangxi Provincial Education Department(No.GJJ210835).
文摘Laser powder bed fusion(LPBF)makes it possible for biodegradable zinc(Zn)to be used to produce customized orthopedic implants.In this research,we investigate the impact of laser power and scanning speed on the development of surface quality,relative densification,and texture during LPBF of Zn implants.Increasing laser power was able to decrease melt viscosity and surface tension,which improved the metallurgical bonding between adjacent tracks.Uneven and twisted tracks also became continuous and straight.Scanning speed could controlmolten-pool temperature to restrain grain natural orientation,achieving various crystal orientations and a weakened texture.Importantly,it further avoided the thermal expansion and contraction caused by excessive energy storage and accumulation in the matrix,thus reducing the generation of high-dislocation density.As a result,by selecting a reasonable laser power and scanning speed,the LPBF parts exhibited a flat surface morphology and a high density over 99.5%.Their average hardness,mechanical strength,and elongation reached 50.2 HV,127.8 MPa,and 7.6%,respectively.Additionally,the parts displayed a moderate degradation rate and excellent osteogenic properties.All these results provide a basis for selecting process parameters to optimize the comprehensive properties of LPBF-processed Zn parts for biodegradable applications.
基金This work was supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030the National Natural Science Foundation of China(No.91860131and No.52074157)+2 种基金Guangdong Provincial Department of Science and Technology,Key-Area Research and Development Program of Guangdong Province(No.2020B090923002)the National Key Research and Development Program of China(No.2017YFB0702901)the Shenzhen Science and Technology Innovation Commission(No.JCYJ20170817111811303,No.KQTD20170328154443162and No.ZDSYS201703031748354).
文摘The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems.However,the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states,inevitably leading to severe metallurgical defects in Ni-based superalloys.Cracks are the greatest threat to these materials’integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure.Consequently,there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking,as this knowledge will enable the wider application of these unique materials.To this end,this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM.In addition,several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.
基金This research was funded by the National Natural Science Foundation of China(Grant number No.52175324)the APC was funded by the Innovation Capability Improvement Project of higher education institutions in Gansu Province of China in 2019(No.2019-198A).
文摘Additive manufacturing(AM)technology makes parts through layer-by-layer deposition,which can regulate the microstructure and properties of different parts of a single part well.It provides a new idea for the preparation of functionally gradient materials(FGM),and has become a research hotspot at present.By referring to and analyzing the recent research achievements in the additive manufacturing tech-nology of FGM,the latest research progress at domestic and abroad from four aspects were summaried:selective laser melting additive man-ufacturing,electron beam additive manufacturing,arc additive manufacturing,path planning,and material texture.Moreover,the existing problems in the research are pointed out,and the future research direction and focus are prospected.
基金Supported by National Natural Science Foundation of China(Grant No.52075100)Shanghai Municipal Science and Technology Committee Innovation Program(Grant No.23ZR1404200).
文摘Additive manufacturing (AM) technology such as selective laser melting (SLM) often produces a high refection phenomenon that makes defect detection and information extraction challenging. Meanwhile, it is essential to establish a characterization method for defect analysis to provide sufcient information for process diagnosis and optimization. However, there is still a lack of universal standards for the characterization of defects in SLM parts. In this study, a polarization-based imaging system was proposed, and a set of characterization parameters for SLM defects was established. The contrast, defect contour information, and high refection suppression efect of the SLM part defects were analyzed. Comparative analysis was conducted on defect characterization parameters, including geometric and texture parameters. The experimental results demonstrated the efects of the polarization imaging system and verifed the feasibility of the defect feature extraction and characterization method. The research work provides an efective solution for defect detection and helps to establish a universal standard for defect characterization in additive manufacturing.
基金Alexander von Humboldt Foundation for the award of the Post-Doctoral Fellowship to M.Marvi-Mashhadi to undertake this research workthe support from the Bundesministerium für Bildung und Forschung(BMBF)through Bio Mag3D project code Nr.03VP09852 to undertake this research。
文摘In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon atmosphere.Compression tests were performed on as sintered parts.Additionally,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental results.The experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.
基金supported by the Natural Science Foundation of Shenyang,China(Grant No.22315605).
文摘A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy was designed using the cluster formula approach(cluster-plus-glue-atom model)and prepared by laser melting deposition(LMD).Its composition formula 12[Al-Ti_(12)](AlTi_(2))+5[Al_(0.8)Si_(0.2)-Ti_(12)Zr_(2)](V_(0.8)Mo_(0.2)Nb_(1)Ti)features an enhancedβ-Ti via co-alloying of Zr,V,Mo,Nb and Si.The experimental results show that the cluster formula ofαandβphases in the novel alloy are respectivelyα-[Al-Ti_(11.5)Zr_(0.5)](Al_(1)Ti_(2))andβ-[Al_(0.8)Si_(0.2)-Ti_(13.2)Zr_(0.8)](V_(1)Mo_(0.4)Nb_(1.6)),both containing Zr elements.The fitted composition via the α andβphase cluster formulas has little difference with the actual alloy composition,suggesting that the validity of cluster-plus-glue-atom model in the alloy composition design.After hot isostatic pressing(HIP),both the Ti-6Al-4V and the novel alloy by LMD are characterized by prior-βcolumnar grains,while the typical<100>texture disappears.Compared with Ti-6Al-4V,Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy exhibits a combination of higher strength(1,056 MPa)and higher ductility(14%)at room temperature and higher strength(580 MPa)at 550℃ after HIP,and can potentially serves as LMD materials.
基金supported by the Technology Development Fund of the China Academy of Machinery Science and Technology(No.170221ZY01).
文摘As a new type of lightweight structure,metallic lattice structure has higher stiffness and strength to weight ratio.To freely obtain 316L lattice structures with designed cell structure and adjustable porosity,additive manufacturing combined with investment casting was conducted to fabricate the 316L lattice structures with Kelvin cell.The compression simulation of 316L lattice structures with different porosities was carried out by using the finite element method.The numerical simulation results were verified by compression experiment,and the simulated results were consistent with the compression tests.The compressive mechanical properties of 316L lattice structures are directly related to porosity and independent of strut diameters.The 316L lattice structures with Kelvin cell have a smooth stress-strain curve and obvious plastic platform,and the hump stress-strain curves are avoided.
基金supported by the National Natural Science Foundation of China(51822503,U20A20297,and 51975142)Key-Area Research and Development Program of Guangdong Province,China(2020B090923003)。
文摘Multifunctional structures(MFSs)integrate diverse functions to achieve superior properties.However,conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equipment with multiple stations to achieve the integration of distinct materials and devices—are unable to satisfy the requirements of MFS applications in emerging industries such as aerospace engineering.Motivated by the concept of design for manufacturing,we adopt a layer regulation method with an established optimization model to design typical MFSs with load-bearing,electric,heat-conduction,and radiation-shielding functions.A high-temperature in situ additive manufacturing(AM)technology is developed to print various metallic wires or carbon fiber-reinforced high-meltingpoint polyetheretherketone(PEEK)composites.It is found that the MFS,despite its low mass,exceeds the stiffness of the PEEK substrate by 21.5%.The embedded electrics remain functional after the elastic deformation stage.Compared with those of the PEEK substrate,the equivalent thermal conductivity of the MFS beneath the central heat source area is enhanced by 568.0%,and the radiation shielding is improved by 27.9%.Moreover,a satellite prototype with diverse MFSs is rapidly constructed as an illustration.This work provides a systematic approach for high-performance design and advanced manufacturing,which exhibits considerable prospects for both the function expansion and performance enhancement of industrial equipment.
基金Funded by the National Natural Science Foundation of China(No.51775068)。
文摘We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.
基金National Natural Science Foundation of China (51935014,52165043, 82072084, 81871498)Jiang Xi Provincial Natural Science Foundation of China (20192ACB20005,2020ACB214004)+6 种基金The Provincial Key R&D Projects of Jiangxi (20201BBE51012)Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme (2018)Shenzhen Science and Technology Plan Project (JCYJ20170817112445033)Innovation Team Project on University of Guangdong Province(2018GKCXTD001)Technology Innovation Platform Project of Shenzhen Institute of Information Technology 2020(PT2020E002)China Postdoctoral Science Foundation(2020M682114)Open Research Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology。
文摘Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degradation. In this work, mesoporous bioglass(MBG)with high pore volume(0.59 cc/g) and huge specific surface area(110.78 m^(2)/g) was synthesized using improved sol-gel method, and introduced into Mg-based composite via laser additive manufacturing. Immersion tests showed that the incorporated MBG served as powerful adsorption sites, which promoted the in-situ deposition of apatite by successively adsorbing Ca2+and HPO42-. Such dense apatite film acted as an efficient protection layer and enhanced the corrosion resistance of Mg matrix, which was proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg based composite showed a significantly decreased degradation rate of 0.31 mm/year. Furthermore,MBG also improved the mechanical properties as well as cell behavior. This work highlighted the advantages of MBG in the fabrication of Mg-based implant with enhanced overall performance for orthopedic application.
基金This work was financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120078,2021A1515111140,and 2021B1515120059)National Key Research and Development Project of China(No.2020YFC1107202)+3 种基金Science Research Cultivation Program(PY2022002)Science and Technology Planning Project of Guangzhou(No.202206010030)City University of Hong Kong Donation Research Grants[DONRMG No.9229021 and 9220061]as well as City University of Hong Kong Strategic Research Grant[SRG 7005505].
文摘Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.