Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend ...Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend the service lifespan of EMI shielding materials,degradation of its protection capability and insufficient self-healing are troublesome issues due to unavoidable physical/chemical damages under long-term application conditions.Here,we report,for the first time,an instantaneously self-healing approach via microwave heating to achieve durable shielding performance.First,a hydrophobic 1H,1H,2H,2H-perfluorooctyltriethoxysilane(POTS)layer was coated on a polypyrrole(PPy)-modified fabric(PPy@POTS),enabling protection against the invasion of water,salt solution,and corrosive acidic and basic solutions.Moreover,after being damaged,the POTS layer can,for the first time,be instantaneously self-healed via microwave heating for a very short time,i.e.,4 s,benefiting from the intense thermal energy generated by PPy under electromagnetic wave radiation.This self-healing ability is also repeatable even after intentionally severe plasma etching,which highlights the great potential to achieve robust and durable EMI shielding applications.Significantly,this approach can be extended to other EMI shielding materials where heat is a triggering stimulus for healing thin protection layers.We envision that this work could provide insights into fabricating EMI shielding materials with durable performance for portable and wearable devices,as well as for human health care.展开更多
Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometrie...Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometries,and harsh environments.In this work,oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni-Cu-P functionalization of(Fe_(0.76)Si_(0.09)B_(0.1)P_(0.05))_(99)Nb_(1)amorphous powder precursors and then thermal spraying them onto aluminum(Al)substrate.Benefiting from the unique magnetic-electric structure,the coating@Al composite delivered prominent EMI shielding performance.The EMI shielding effectiveness(SE)of modified coating@Al composite is~41 dB at 8-12 GHz,doubling the value of Al substrate and is 15 dB greater than that of Ni-Cu-P-free coating@Al composite.Microstructure analysis showed that the introduced Ni−Cu−P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic matrix.Electron holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu−P conductive network,magnetic loss from Fe-based amorphous coating,and the electromagnetic interactions in the oriented segregated architectures.Moreover,the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading environments.Our work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms.展开更多
Controlling the orientation of two-dimensional MXene within layered films is essential to optimize or tune their mechanical properties and electromagnetic interference shielding(EMI)performance,but achieving the high ...Controlling the orientation of two-dimensional MXene within layered films is essential to optimize or tune their mechanical properties and electromagnetic interference shielding(EMI)performance,but achieving the high orientation MXene layers on an industrial scale remains a challenging goal.In this paper,a scalable layer-by-layer blade coating(LbLBC)method was employed to fabricate highly oriented MXene/polyvinyl alcohol(PVA)films.During the LbLBC process,MXene/PVA colloid suffered a strong shearing effect,which induced the ordered alignment of MXene nanosheets along the direction of the blade movement.The orientation of MXene can be effectively adjusted by changing the scraping gap of LbLBC,achieving a maximum Herman orientation factor f of 0.81.As a result,the mechanical properties and EMI performance of the as-prepared MXene/PVA films are in direct proportion to their orientation,with the optimal values of tensile strength of 145.5 MPa,fracture strain of 19.6%,toughness of 17.7 MJ·m^(−3),and EMI shielding effectiveness of 36.7 dB.Furthermore,the inherently low mid-infrared(mid-IR)emissivity of MXene,combined with the densely oriented structure affords the composite films with IR stealth,resulting in a substantial decrease from 150 to 66.1℃in the radiative temperature of a surface.Conclusively,these scalable MXene/PVA films exhibit remarkable potential for integration into the next generation of multifunctional protective camouflage materials.展开更多
To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in poly...To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer matrices.Herein,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne polyurethane.The 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the MXene.The resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µm.In addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 V.The multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.展开更多
Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding perfo...Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding performance.The research process ofMg-Li alloys is reviewed and three main problems are pointed out.Aimed at the poor corrosion resistance of Mg-Li alloys,thecorrosion behavior is mainly summarized.The surface treatment technologies,including electroplating,electroless plating,plasmaspraying,molten salt replacement,conversion coating,anodizing,micro-arc oxidation,organic coating,and organic-inorganic hybridcoating,are introduced in detail.Finally,the future development of corrosion and protection of Mg?Li alloys is discussed.展开更多
An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate compo...An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate composed of aramid and carbon fibers was innovatively used in flexible Electromagnetic Interference(EMI)shielding materials.The natural network structure is advantageous to the uniform deposition of metal particles to the establishment of conductive pathways subsequently in order to improve conductivity.The induction of a synergistic effect from Electromagnetic(EM)wave-reflection and EM wave-absorption through the whole carbonCo-Ni-ternary system notably enhanced the EMI Shielding Effectiveness(SE)value to an average of 42.57 d B in the range of 30-6000 MHz.On the other hand,together with the inherent toughness of the alloy coatings,the tensile strength of the aramid fibers used for bulletproof made a significant contribution to the desired mechanical properties.The light weight of the resultant composite made it applicable to aerospace vehicles simultaneously.X-ray Photoelectron Spectroscopy(XPS)was conducted to investigate the variations of elements and groups on the sample surface in pretreating process.The elemental components and surface morphologies of fabric samples during different stages of the process were investigated by Scanning Electron Microscope(SEM)and Energy Dispersive spectrometer(EDX)measurements.X-Ray Diffraction(XRD)results indicated that the obtained Co-Ni alloy coating had a combined Hexagonal Closed-Packed(HCP)and FacedCentered Cubic(FCC)crystalline phase.The relatively high corrosion resistance demonstrated in different acid and alkaline conditions was instrumental in more complex environments as well.展开更多
基金L.Z.and C.L.contributed equally to this work.This work was supported by the Natural Science Foundation of China(No.51903001)Anhui Province International Science and Technology Cooperation Program(No.1804b06020360)+2 种基金Anhui Province International Cooperation Research Center of Textile Structure Composites(No.2021ACTC07)Research Funds of Anhui Polytechnic University(No.Xjky2020041)S.C.T.acknowledges the financial support from MOE AcRF2(R-284-000-217-112).
文摘Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend the service lifespan of EMI shielding materials,degradation of its protection capability and insufficient self-healing are troublesome issues due to unavoidable physical/chemical damages under long-term application conditions.Here,we report,for the first time,an instantaneously self-healing approach via microwave heating to achieve durable shielding performance.First,a hydrophobic 1H,1H,2H,2H-perfluorooctyltriethoxysilane(POTS)layer was coated on a polypyrrole(PPy)-modified fabric(PPy@POTS),enabling protection against the invasion of water,salt solution,and corrosive acidic and basic solutions.Moreover,after being damaged,the POTS layer can,for the first time,be instantaneously self-healed via microwave heating for a very short time,i.e.,4 s,benefiting from the intense thermal energy generated by PPy under electromagnetic wave radiation.This self-healing ability is also repeatable even after intentionally severe plasma etching,which highlights the great potential to achieve robust and durable EMI shielding applications.Significantly,this approach can be extended to other EMI shielding materials where heat is a triggering stimulus for healing thin protection layers.We envision that this work could provide insights into fabricating EMI shielding materials with durable performance for portable and wearable devices,as well as for human health care.
基金supported by National Key Research and Development Program of China(No.2016YFB0300500)National Natural Science Foundation of China(No.51771215)+1 种基金Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025(No.2018B10084)China Postdoctoral Science Foundation(No.2020M673174)。
文摘Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometries,and harsh environments.In this work,oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni-Cu-P functionalization of(Fe_(0.76)Si_(0.09)B_(0.1)P_(0.05))_(99)Nb_(1)amorphous powder precursors and then thermal spraying them onto aluminum(Al)substrate.Benefiting from the unique magnetic-electric structure,the coating@Al composite delivered prominent EMI shielding performance.The EMI shielding effectiveness(SE)of modified coating@Al composite is~41 dB at 8-12 GHz,doubling the value of Al substrate and is 15 dB greater than that of Ni-Cu-P-free coating@Al composite.Microstructure analysis showed that the introduced Ni−Cu−P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic matrix.Electron holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu−P conductive network,magnetic loss from Fe-based amorphous coating,and the electromagnetic interactions in the oriented segregated architectures.Moreover,the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading environments.Our work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms.
基金the National Natural Science Foundation of China(Nos.52273085,52303113,and 12072325)the Natural Science Foundation of China of Henan Province(No.222300420541)the Key Scientific Research Projects of Colleges and Universities in Henan Province,China(No.24A430045).
文摘Controlling the orientation of two-dimensional MXene within layered films is essential to optimize or tune their mechanical properties and electromagnetic interference shielding(EMI)performance,but achieving the high orientation MXene layers on an industrial scale remains a challenging goal.In this paper,a scalable layer-by-layer blade coating(LbLBC)method was employed to fabricate highly oriented MXene/polyvinyl alcohol(PVA)films.During the LbLBC process,MXene/PVA colloid suffered a strong shearing effect,which induced the ordered alignment of MXene nanosheets along the direction of the blade movement.The orientation of MXene can be effectively adjusted by changing the scraping gap of LbLBC,achieving a maximum Herman orientation factor f of 0.81.As a result,the mechanical properties and EMI performance of the as-prepared MXene/PVA films are in direct proportion to their orientation,with the optimal values of tensile strength of 145.5 MPa,fracture strain of 19.6%,toughness of 17.7 MJ·m^(−3),and EMI shielding effectiveness of 36.7 dB.Furthermore,the inherently low mid-infrared(mid-IR)emissivity of MXene,combined with the densely oriented structure affords the composite films with IR stealth,resulting in a substantial decrease from 150 to 66.1℃in the radiative temperature of a surface.Conclusively,these scalable MXene/PVA films exhibit remarkable potential for integration into the next generation of multifunctional protective camouflage materials.
基金the National Natural Science Foundation of China(Nos.51922020 and 52090034)the Fundamental Research Funds for the Central Universities(Nos.BHYC1707B and XK1802-2).
文摘To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer matrices.Herein,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne polyurethane.The 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the MXene.The resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µm.In addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 V.The multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.
基金Project(2017zzts005) supported by the Fundamental Research Funds for the Central Universities of Central South University
文摘Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding performance.The research process ofMg-Li alloys is reviewed and three main problems are pointed out.Aimed at the poor corrosion resistance of Mg-Li alloys,thecorrosion behavior is mainly summarized.The surface treatment technologies,including electroplating,electroless plating,plasmaspraying,molten salt replacement,conversion coating,anodizing,micro-arc oxidation,organic coating,and organic-inorganic hybridcoating,are introduced in detail.Finally,the future development of corrosion and protection of Mg?Li alloys is discussed.
基金supported by the National Natural Science Foundation of China(No.U1830108)the Shanghai Natural Science Foundation,China(No.20ZR1405000)+1 种基金the Innovation Foundation of Shanghai Aerospace Science and Technology,China(No.SAST2018-061)the Exploratory Research Project of“Yanchang Petroleum(Group)-Fudan University”,China。
文摘An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate composed of aramid and carbon fibers was innovatively used in flexible Electromagnetic Interference(EMI)shielding materials.The natural network structure is advantageous to the uniform deposition of metal particles to the establishment of conductive pathways subsequently in order to improve conductivity.The induction of a synergistic effect from Electromagnetic(EM)wave-reflection and EM wave-absorption through the whole carbonCo-Ni-ternary system notably enhanced the EMI Shielding Effectiveness(SE)value to an average of 42.57 d B in the range of 30-6000 MHz.On the other hand,together with the inherent toughness of the alloy coatings,the tensile strength of the aramid fibers used for bulletproof made a significant contribution to the desired mechanical properties.The light weight of the resultant composite made it applicable to aerospace vehicles simultaneously.X-ray Photoelectron Spectroscopy(XPS)was conducted to investigate the variations of elements and groups on the sample surface in pretreating process.The elemental components and surface morphologies of fabric samples during different stages of the process were investigated by Scanning Electron Microscope(SEM)and Energy Dispersive spectrometer(EDX)measurements.X-Ray Diffraction(XRD)results indicated that the obtained Co-Ni alloy coating had a combined Hexagonal Closed-Packed(HCP)and FacedCentered Cubic(FCC)crystalline phase.The relatively high corrosion resistance demonstrated in different acid and alkaline conditions was instrumental in more complex environments as well.
