Microlattices pose ample opportunity for constructing light weight structures for the automotive and aerospace industries.Laser powder bed fusion is an appealing technique to fabricate these structures because of its ...Microlattices pose ample opportunity for constructing light weight structures for the automotive and aerospace industries.Laser powder bed fusion is an appealing technique to fabricate these structures because of its capabilities to process high-resolution complex architectured structures.In this work we explore the use of a 718 oxide dispersion strengthened alloy to create three microlattice structures designed in nTop,a straight bar,honeycomb and body-centered cubic(BCC)microlattice and investigate the effects of architectures on tensile behavior of the microlattices in a scanning electron microscope.The straight bar configurations deliver high strength but low ductility.The BCC lattices are highly deformable but soft.The honeycomb has an attractive combination of high strength and pronounced work hardening.Furthermore,electron backscattered diffraction studies revealed substantial crystallographic reorientation and grain refinement in the honeycomb lattice during deformation,in contrast to little crystal orientation change in the straight bar specimens.This study suggests that architectures play a significant role in the tensile behavior and deformation mechanisms in metallic materials.展开更多
Incorporating high-entropy alloys(HEAs) in composite microlattice structures yields superior mechanical performance and desirable functional properties compared to conventional metallic lattices. However, the modulus ...Incorporating high-entropy alloys(HEAs) in composite microlattice structures yields superior mechanical performance and desirable functional properties compared to conventional metallic lattices. However, the modulus mismatch and relatively poor adhesion between the soft polymer core and stiff metallic film coating often results in film delamination and brittle strut fracture at relatively low strain levels(typically below 10%). In this work, we demonstrate that optimizing the HEA film thickness of a CoCrNiFe-coated microlattice completely suppresses delamination,significantly delays the onset of strut fracture(~100% increase in compressive strain),and increases the specific strength by up to 50%. This work presents an efficient strategy to improve the properties of metal-composite mechanical metamaterials for structural applications.展开更多
Precursor-derived ceramic SiOC(PDC-SiOC)microlattices exhibit excellent oxidation resistance,high-temperature stability,and superior mechanical properties.However,the printing accuracy of the PDC-SiOC microlattices by...Precursor-derived ceramic SiOC(PDC-SiOC)microlattices exhibit excellent oxidation resistance,high-temperature stability,and superior mechanical properties.However,the printing accuracy of the PDC-SiOC microlattices by 3D printing is still limited,and mechanical properties of the PDC-SiOC microlattices have not been studied systematically.Here,PDC-SiOC octet microlattices were fabricated by projection micro stereolithography(PμSL)3D printing,and photoabsorber(Sudan III)’s effect on the accuracy was systematically analyzed.The results showed that the addition of Sudan III improved the printing accuracy significantly.Then,the ceramization process of the green body was analyzed in detail.The order of the green body decreased,and most of their chemical bonds were broken during pyrolysis.After that,the PDC-SiOC microlattices with different truss diameters in the range of 52–220μm were fabricated,and their mechanical properties were investigated.The PDC-SiOC microlattices with a truss diameter of 52μm exhibited higher compression strength(31 MPa)than those with bigger truss diameters.The size effect among the PDC-SiOC microlattices was analyzed.Our work provides a deeper insight into the manufacturing of PDC-SiOC micro-scaled architectures by 3D printing and paves a path to the research of the size effect in ceramic structures.展开更多
Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables th...Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables the production of customized 3D microlattices with feature sizes down to several microns.However,the mechanical properties of as-printed polymers were not systemically studied at the relevant length scales,especially when the feature sizes step into micron/sub-micron level,limiting its reliable performance prediction in micro/nanolattice and other metamaterial applications.In this work,we demonstrate that PμSL-printed microfibers could become stronger and significantly more ductile with reduced size ranging from 20μm to 60μm,showing an obvious size-dependent mechanical behavior,in which the size decreases to 20μm with a fracture strain up to~100%and fracture strength up to~100 MPa.Such size effect enables the tailoring of the material strength and stiffness of PμSL-printed microlattices over a broad range,allowing to fabricate the microlattice metamaterials with desired/tunable mechanical properties for various structural and functional applications.展开更多
A compatible artificialbone impla nt requires large pores for enhanced nutrients transports,small pores to allow cell seeding and bone-like mechanical properties to avoid stress shielding.Herein,we report novel improv...A compatible artificialbone impla nt requires large pores for enhanced nutrients transports,small pores to allow cell seeding and bone-like mechanical properties to avoid stress shielding.Herein,we report novel improved gyroid lattices with millimetre-scaled gyroid wall spacings and micrometre-scaled additional pores on the walls.Designs are successfully fabricated by electron beam melting using Ti-6 Al-4 V to high part qualities while exhibiting bone-like mechanical properties with a range of Young's modulus of 8-15 GPa and strength of 150-250 MPa.The improved design also eliminates brittle failure by allowing the structure to deform more stably.展开更多
A method was developed and proposed to fabricate graphene-enhanced hollow microlattice materials,which include the three-dimensional(3D)printing,nanocomposite electroless plating,and polymer etching technologies.The s...A method was developed and proposed to fabricate graphene-enhanced hollow microlattice materials,which include the three-dimensional(3D)printing,nanocomposite electroless plating,and polymer etching technologies.The surface morphology and uniformity of as-deposited coatings were systematically characterized and analyzed.Moreover,the mechanical properties of the microlattices were investigated through quasi-static compression tests.The results demonstrated that a uniform Nickel-phossphorous-graphene(Ni-P-G)coating was obtained successfully,and the specific modulus and strength were increased by adding graphene into the microlattice materials.The optimal mass concentration of graphene nanoplatelets was obtained after comparing the specific modulus and strength of the materials with different densities of graphene,and the strength mechanism was discussed.展开更多
The notorious growth of sodium dendrites and significant volume fluctuations have posed substantial challenges to the practical application of sodium metal anodes.In this work,an aerogel composed of MgF_(2) nanopartic...The notorious growth of sodium dendrites and significant volume fluctuations have posed substantial challenges to the practical application of sodium metal anodes.In this work,an aerogel composed of MgF_(2) nanoparticles(NPs)onto a three-dimensional(3D)printed reduced graphene oxide(rGO)(MgF_(2)/rGO)monolith was employed as a scaffold for sodium metal anodes.During the initial discharge process,the MgF_(2) NPs underwent an electrochemical in-situ conversion into NaF and sodiophilic Mg NPs,which act as the Na metal nucleation centers and contribute to the formation of a stable solid electrolyte interface(SEI)layer.Benefiting from these synergistic effects,the 3D printed MgF_(2)/rGO electrode exhibits a high Coulombic efficiency of 99.49% after 1200 cycles at 0.5 mA·cm^(-2) with 1 mAh·cm^(-2).It also shows a long cycle lifespan of 2500 h with a high capacity of 10 mAh·cm^(-2) at 5 mA·cm^(-2).Moreover,when assembled into a full cell with a Na@MgF_(2)/rGO anode and a Na3V2(PO4)3@C-rGO cathode,the cell delivers an extended cycle life of 3500 cycles at 1 C,preserving a reversible capacity of 86.98 mAh·g^(-1).This work paves the way for utilization of 3D printed metal-fluorides to enhance the electrochemical performance of the sodium metal anodes.展开更多
基金Benjamin Stegman and Xinghang Zhang would like to acknowledge the financial support from the NSF-DFG CMMI grant(No.2228266)Benjamin Stegman and Haiyan Wang acknowledge the partial support from the U.S.Office of Naval Research(ONR,No.N00014-22-1-2160)for microscopy analysis.
文摘Microlattices pose ample opportunity for constructing light weight structures for the automotive and aerospace industries.Laser powder bed fusion is an appealing technique to fabricate these structures because of its capabilities to process high-resolution complex architectured structures.In this work we explore the use of a 718 oxide dispersion strengthened alloy to create three microlattice structures designed in nTop,a straight bar,honeycomb and body-centered cubic(BCC)microlattice and investigate the effects of architectures on tensile behavior of the microlattices in a scanning electron microscope.The straight bar configurations deliver high strength but low ductility.The BCC lattices are highly deformable but soft.The honeycomb has an attractive combination of high strength and pronounced work hardening.Furthermore,electron backscattered diffraction studies revealed substantial crystallographic reorientation and grain refinement in the honeycomb lattice during deformation,in contrast to little crystal orientation change in the straight bar specimens.This study suggests that architectures play a significant role in the tensile behavior and deformation mechanisms in metallic materials.
基金funding for this work from Shenzhen Science and Technology Innovation Committee under the Grant JCYJ20170413141157573Part of this project was supported by City University of Hong Kong (Project Nos. 9667164)。
文摘Incorporating high-entropy alloys(HEAs) in composite microlattice structures yields superior mechanical performance and desirable functional properties compared to conventional metallic lattices. However, the modulus mismatch and relatively poor adhesion between the soft polymer core and stiff metallic film coating often results in film delamination and brittle strut fracture at relatively low strain levels(typically below 10%). In this work, we demonstrate that optimizing the HEA film thickness of a CoCrNiFe-coated microlattice completely suppresses delamination,significantly delays the onset of strut fracture(~100% increase in compressive strain),and increases the specific strength by up to 50%. This work presents an efficient strategy to improve the properties of metal-composite mechanical metamaterials for structural applications.
基金supported by the National Natural Science Foundation of China(No.52275310)the Open Project of State Key Laboratory of Explosion Science and Technology(No.QNKT22-15)the characterization at the Analysis&Testing Center,Beijing Institute of Technology.
文摘Precursor-derived ceramic SiOC(PDC-SiOC)microlattices exhibit excellent oxidation resistance,high-temperature stability,and superior mechanical properties.However,the printing accuracy of the PDC-SiOC microlattices by 3D printing is still limited,and mechanical properties of the PDC-SiOC microlattices have not been studied systematically.Here,PDC-SiOC octet microlattices were fabricated by projection micro stereolithography(PμSL)3D printing,and photoabsorber(Sudan III)’s effect on the accuracy was systematically analyzed.The results showed that the addition of Sudan III improved the printing accuracy significantly.Then,the ceramization process of the green body was analyzed in detail.The order of the green body decreased,and most of their chemical bonds were broken during pyrolysis.After that,the PDC-SiOC microlattices with different truss diameters in the range of 52–220μm were fabricated,and their mechanical properties were investigated.The PDC-SiOC microlattices with a truss diameter of 52μm exhibited higher compression strength(31 MPa)than those with bigger truss diameters.The size effect among the PDC-SiOC microlattices was analyzed.Our work provides a deeper insight into the manufacturing of PDC-SiOC micro-scaled architectures by 3D printing and paves a path to the research of the size effect in ceramic structures.
基金the financial support from Shenzhen Science and Technology Innovation Committee under the Grant Nos. JCYJ20170818103206501, Type C 202011033000145Changsha Municipal Science and Technology Bureau Project kh2201035supported by the City University of Hong Kong under the Grant No. 9667226
文摘Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables the production of customized 3D microlattices with feature sizes down to several microns.However,the mechanical properties of as-printed polymers were not systemically studied at the relevant length scales,especially when the feature sizes step into micron/sub-micron level,limiting its reliable performance prediction in micro/nanolattice and other metamaterial applications.In this work,we demonstrate that PμSL-printed microfibers could become stronger and significantly more ductile with reduced size ranging from 20μm to 60μm,showing an obvious size-dependent mechanical behavior,in which the size decreases to 20μm with a fracture strain up to~100%and fracture strength up to~100 MPa.Such size effect enables the tailoring of the material strength and stiffness of PμSL-printed microlattices over a broad range,allowing to fabricate the microlattice metamaterials with desired/tunable mechanical properties for various structural and functional applications.
基金financially supported by A*STAR Industrial Additive Manufacturing Program:Work Package 3(Electron Beam Melting,Grant No.1325504103)the A*STAR Additive Manufacturing Centre(AMC)Initiative:Work Package 1(High Temperature Materials Development for 3D Additive Manufacturing,Grant No.1426800088)。
文摘A compatible artificialbone impla nt requires large pores for enhanced nutrients transports,small pores to allow cell seeding and bone-like mechanical properties to avoid stress shielding.Herein,we report novel improved gyroid lattices with millimetre-scaled gyroid wall spacings and micrometre-scaled additional pores on the walls.Designs are successfully fabricated by electron beam melting using Ti-6 Al-4 V to high part qualities while exhibiting bone-like mechanical properties with a range of Young's modulus of 8-15 GPa and strength of 150-250 MPa.The improved design also eliminates brittle failure by allowing the structure to deform more stably.
基金National Natural Science Foundation of China(No.U1637105)Fundamental Research Funds for the Central Universities(No.17X100040056)。
文摘A method was developed and proposed to fabricate graphene-enhanced hollow microlattice materials,which include the three-dimensional(3D)printing,nanocomposite electroless plating,and polymer etching technologies.The surface morphology and uniformity of as-deposited coatings were systematically characterized and analyzed.Moreover,the mechanical properties of the microlattices were investigated through quasi-static compression tests.The results demonstrated that a uniform Nickel-phossphorous-graphene(Ni-P-G)coating was obtained successfully,and the specific modulus and strength were increased by adding graphene into the microlattice materials.The optimal mass concentration of graphene nanoplatelets was obtained after comparing the specific modulus and strength of the materials with different densities of graphene,and the strength mechanism was discussed.
基金supported by the Natural Science Foundation of Henan Province(Nos.252300421283 and 242300421427)Tackling Key Scientific and Technological Problems of the Henan Province(No.242102220104)the Major Science and Technology Projects of Henan Province(No.231100230300).
文摘The notorious growth of sodium dendrites and significant volume fluctuations have posed substantial challenges to the practical application of sodium metal anodes.In this work,an aerogel composed of MgF_(2) nanoparticles(NPs)onto a three-dimensional(3D)printed reduced graphene oxide(rGO)(MgF_(2)/rGO)monolith was employed as a scaffold for sodium metal anodes.During the initial discharge process,the MgF_(2) NPs underwent an electrochemical in-situ conversion into NaF and sodiophilic Mg NPs,which act as the Na metal nucleation centers and contribute to the formation of a stable solid electrolyte interface(SEI)layer.Benefiting from these synergistic effects,the 3D printed MgF_(2)/rGO electrode exhibits a high Coulombic efficiency of 99.49% after 1200 cycles at 0.5 mA·cm^(-2) with 1 mAh·cm^(-2).It also shows a long cycle lifespan of 2500 h with a high capacity of 10 mAh·cm^(-2) at 5 mA·cm^(-2).Moreover,when assembled into a full cell with a Na@MgF_(2)/rGO anode and a Na3V2(PO4)3@C-rGO cathode,the cell delivers an extended cycle life of 3500 cycles at 1 C,preserving a reversible capacity of 86.98 mAh·g^(-1).This work paves the way for utilization of 3D printed metal-fluorides to enhance the electrochemical performance of the sodium metal anodes.
