Nickel based single crystal superalloy is currently widely used as the material for turbine blades in aerospace engines.However,metallurgical defects during the manufacturing process and damage during harsh environmen...Nickel based single crystal superalloy is currently widely used as the material for turbine blades in aerospace engines.However,metallurgical defects during the manufacturing process and damage during harsh environmental service are inevitable challenges for turbine blades.Therefore,bonding techniques play a very important role in the manufacturing and repair of turbine blades.The transient liquid phase(TLP)bonding of DD5 Ni-based single crystal superalloy was performed using the designed H1 interlayer.A new third-generation Ni-based superalloy T1 powder was mixed with H1 powder as another interlayer to improve the mechanical properties of the bonded joints.The res-ults show that,such a designed H1 interlayer is beneficial to the improvement of shear strength of DD5 alloy bonded joints by adjusting the bonding temperature and the prolongation of holding time.The maximum shear strength at room temperature of the joint with H1 interlayer reached 681 MPa when bonded at 1260℃for 3 h.The addition of T1 powder can effectively reduce holding time or relatively lower bond-ing temperature,while maintaining relatively high shear strength.When 1 wt.%T1 powder was mixed into H1 interlayer,the maximum room temperature shear strength of the joint bonded at 1260℃reached 641 MPa,which could be obtained for only 1 h.Considering the bonding temperature and the efficiency,the acceptable process parameter of H1+5 wt.%T1 interlayer was 1240℃/2 h,and the room tem-perature shear strength reached 613 MPa.展开更多
High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bon...High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bonding strength reaches a maximum of 6.2 MPa.In addition,a thermal stress model for GaAs/Si wafers is established based on finite element analysis to obtain the distribution of equivalent stress and deformation variables at different temperatures.The shape varia-tion of the wafer is directly proportional to the annealing temperature.At an annealing temperature of 400℃,the maximum protrusion of 4 inches GaAs/Si wafers is 3.6 mm.The interface of GaAs/Si wafers is observed to be dense and defect-free using a transmission electron microscope.The characterization of interface elements by X-ray energy dispersion spectroscopy indi-cates that the elements at the interface undergo mutual diffusion,which is beneficial for improving the bonding strength of the interface.There is an amorphous transition layer with a thickness of about 5 nm at the bonding interface.The preparation of Si-based GaAs heterojunctions can enrich the types of materials required for the development of integrated circuits,improve the performance of materials and devices,and promote the development of microelectronics technology.展开更多
Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have ...Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical design.In this work,we report two designed hybrid copper(I)iodides,(Ph_(3)MeP)_(2)Cu_(4)I_(6)and(Cy_(3)MeP)_(2)Cu_(4)I_(6),as blue-light-excitable yellow phosphors with ultrabroadband emission.In these compounds,the[Cu_(4)I_(6)]^(2-)anion forms an I6 octahedron centered on a cationic Cu_(4)tetrahedron.The strong cation-cation bonding within the unique cationic Cu_(4)tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)iodides.The ultrabroadband emission is attributed to the coexistence of free and self-trapped excitons.The WLED using the[Cu_(4)I_(6)]^(2-)anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W^(-1)and a high color rendering index of 88.This work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.展开更多
Non-destructive detection of wire bonding defects in integrated circuits(IC)is critical for ensuring product quality after packaging.Image-processing-based methods do not provide a detailed evaluation of the three-dim...Non-destructive detection of wire bonding defects in integrated circuits(IC)is critical for ensuring product quality after packaging.Image-processing-based methods do not provide a detailed evaluation of the three-dimensional defects of the bonding wire.Therefore,a method of 3D reconstruction and pattern recognition of wire defects based on stereo vision,which can achieve non-destructive detection of bonding wire defects is proposed.The contour features of bonding wires and other electronic components in the depth image is analysed to complete the 3D reconstruction of the bonding wires.Especially to filter the noisy point cloud and obtain an accurate point cloud of the bonding wire surface,a point cloud segmentation method based on spatial surface feature detection(SFD)was proposed.SFD can extract more distinct features from the bonding wire surface during the point cloud segmentation process.Furthermore,in the defect detection process,a directional discretisation descriptor with multiple local normal vectors is designed for defect pattern recognition of bonding wires.The descriptor combines local and global features of wire and can describe the spatial variation trends and structural features of wires.The experimental results show that the method can complete the 3D reconstruction and defect pattern recognition of bonding wires,and the average accuracy of defect recognition is 96.47%,which meets the production requirements of bonding wire defect detection.展开更多
This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile...This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 Pa.Non-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into MgO.In addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the interface.This process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.展开更多
Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of ne...Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.展开更多
The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulat...The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.展开更多
We put forward a method of fabricating Aluminum(Al)/carbon fibers(CFs) composite sheets by the accumulative roll bonding(ARB) method. The finished Al/CFs composite sheet has CFs and pure Al sheets as sandwich and surf...We put forward a method of fabricating Aluminum(Al)/carbon fibers(CFs) composite sheets by the accumulative roll bonding(ARB) method. The finished Al/CFs composite sheet has CFs and pure Al sheets as sandwich and surface layers. After cross-section observation of the Al/CFs composite sheet, we found that the CFs discretely distributed within the sandwich layer. Besides, the tensile test showed that the contribution of the sandwich CFs layer to tensile strength was less than 11% compared with annealed pure Al sheet. With ex-situ observation of the CFs breakage evolution with-16%,-32%, and-45% rolling reduction during the ARB process, the plastic instability of the Al layer was found to bring shear damages to the CFs. At last, the bridging strengthening mechanism introduced by CFs was sacrificed. We provide new insight into and instruction on Al/CFs composite sheet preparation method and processing parameters.展开更多
One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm ...One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.展开更多
TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure ti...TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding,thereby promoting the formation of an effective mechanical interlock at the interface,which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates.Moreover,the composite plate subjected to oxidation treatment exhibited high shear strength,particularly at a 43%reduction rate,achieving a commendable value of 117 MPa.Based on oxidation treatment and different reduction rates,the annealed composite plates at temperatures of 400,450,and 500°C displayed favorable resistance to interface delamination,highlighting their remarkable strength-plasticity compatibility as evidenced by a maximum elongation of 31.845%.展开更多
This year,Toray Industries,Inc.,announced that it has developed an insulating resin material for hybrid bonding(micro bonding).The material is based on Semicofine™and Photoneece™.These are high-heat-resistant polyimid...This year,Toray Industries,Inc.,announced that it has developed an insulating resin material for hybrid bonding(micro bonding).The material is based on Semicofine™and Photoneece™.These are high-heat-resistant polyimide coatings for semiconductor and display devices.The new material combines a conventional polyimide coating agent with the company’s processing and bonding technologies.It can enhance the yields and reliability of semiconductor devices in the hybrid bonding process,which entails bonding semiconductor chips with metal electrodes.Toray will push ahead with prototyping and providing samples to customers.It aims to obtain materials certification in 2025 and start mass production by 2028.展开更多
In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after ...In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete.The effects of steel corrosion rate,steel bar diameter,steel bar strength grade,and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed.The influence of different corrosion rates on specimens’bonding strength and bond-slip curves was determined,and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed.The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate.Additionally,an increase in corrosive crack width leads to a linear decrease in bonding strength.Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible.Furthermore,a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values,which aligned well with the experimental findings.展开更多
In this work,the ultrasonic assisted active metal soldering of SiO_(2) glass and Al was successfully achieved using Sn-2Ti solder filler at a low soldering temperature of 250℃in ambient atmosphere.A nano-crystalline...In this work,the ultrasonic assisted active metal soldering of SiO_(2) glass and Al was successfully achieved using Sn-2Ti solder filler at a low soldering temperature of 250℃in ambient atmosphere.A nano-crystallineα-Al2O3 layer with the average thickness of 13.9 nm and a nano-crystalline R-TiO_(2) layer with the average thickness of 16.2 nm are formed at the interface of Al/Sn and SiO_(2)/Sn respectively because Al elements did not diffuse from Al alloy side to SiO_(2) side,which verified that a sono-oxidation reaction had occurred during the ultrasonic assisted active metal soldering process.The soldered butt joints exhibited an average tensile strength of 25.31 MPa.展开更多
To evaluate various interlaminar bonding reinforcement techniques used for steel bridge decks,the UHPC surface was roughened with shot blasting(SB),transverse grooving(TG)and surface embedded stone(S),epoxy resin(E),e...To evaluate various interlaminar bonding reinforcement techniques used for steel bridge decks,the UHPC surface was roughened with shot blasting(SB),transverse grooving(TG)and surface embedded stone(S),epoxy resin(E),epoxy asphalt(EA)and high viscosity high elasticity asphalt(HV)as interlayer bonding materials.In addition,a diagonal shear test was conducted using a self-designed diagonal shear jig.The effects of adhesive layer materials type,surface texture type,and different loading rates on the interlaminar bonding performance of UHPC/SMA combination specimens were investigated.The experimental study showed that the peak shear strength and shear modulus of the combined specimen decreased gradually with the decrease of thermosetting of the adhesive layer materials.The peak shear fracture energy of E was greater than that of HV and EA.The synergistic effect of the contact force generated by the roughing of the UHPC surface,the friction force,and the bonding force provided by the adhesive layer material can significantly improve the interlaminar shear performance of the assemblies.The power-law function of shear strength and shear modulus was proposed.The power-law model of peak shear strength and loading rate was verified.The shear strength and predicted shear strength satisfy the positive proportional functions with scale factors of 0.985,1.015,0.961,and 1.028,respectively.展开更多
Dynamic modeling of a parallel manipulator(PM) is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the ...Dynamic modeling of a parallel manipulator(PM) is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.展开更多
Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely co...Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.展开更多
Insulating polymers are characterized by a predominantlyσ-covalent structure,which localize electrons in the atoms and exhibit dielectricity.Insulating polymers typically adopt a more linear and extended conformation...Insulating polymers are characterized by a predominantlyσ-covalent structure,which localize electrons in the atoms and exhibit dielectricity.Insulating polymers typically adopt a more linear and extended conformation,as the repeating units are connected by single covalent bonds,resulting in a relatively straight and extended chain structure.For most insulating polymers,the contour length(L_(c))is significantly larger than their persistence length(Lp)due to the rotation of C−C single bonds(Fig.1(a)).Consequently,this leads to a flexible,random-coil chain conformation.This structural feature contributes to the great mechanical durability and resistance to crack initiation during stretching or bending processes.In contrast,conjugated polymers possess aπ-conjugated molecular structure,allowing electron mobility along the main chain,called delocalization,which imparts semiconducting properties[1,2].The presence of rigid,alternating single and multiple bonds results in comparable Lc and Lp,thereby yielding a stiff or semi-flexible conformation(Fig.1(b))[3,4].As a consequence,most conjugated polymers are prone to fracture under low strain levels(<10%)[5−7].展开更多
Background: Bonding disorders affect the growth and development of infants. In Japan, the Japanese version of the Mother-to-Infant Bonding Scale (MIBS-J) is widely used for early detection of bonding disorders. Repeat...Background: Bonding disorders affect the growth and development of infants. In Japan, the Japanese version of the Mother-to-Infant Bonding Scale (MIBS-J) is widely used for early detection of bonding disorders. Repeated use of a questionnaire has problems of reduced validity. In order to correctly detect bonding disorders at multiple time points, it is necessary to confirm the measurement invariance of the scale. Baba et al. reported that invariance of the MIBS-J factor structure could only be obtained by abridging the scale into three items. Purpose: The aim of this study was to 1) confirm the factor structure and measurement invariance of the MIBS-J between two measurement times and 2) to examine factors that can be used without being affected by measurement time in order to identify item that contribute to measure met invariance. Methods: We analysed the data of 1049 and 878 mothers with a neonate collected in two waves: 5 days (Wave 1) and 1 month postpartum (Wave 2). Exploratory and confirmatory factor analyses were conducted on the data randomly divided into two groups in each wave. Results: The three-item model (MIBS-J items 1, 6, and 8) was most accepted. Measurement invariance and structural invariance were confirmed in the model. This was consistent with Baba et al.’s model. Conclusion: The three MIBS-J items showed measurement invariance and structural invariance in Japanese mothers during 1 month postpartum.展开更多
基金supported by the National Science and Technology Major Project(2017-VI-0009-0080)the Key-Area Research and Development Program of Guangdong Province(2019B010935001)+1 种基金Shenzhen Science and Technology Plan(Project No.JSGG20210802093205015)Industry and Information Technology Bureau of Shenzhen Municipality(Project No.201806071354163490).
文摘Nickel based single crystal superalloy is currently widely used as the material for turbine blades in aerospace engines.However,metallurgical defects during the manufacturing process and damage during harsh environmental service are inevitable challenges for turbine blades.Therefore,bonding techniques play a very important role in the manufacturing and repair of turbine blades.The transient liquid phase(TLP)bonding of DD5 Ni-based single crystal superalloy was performed using the designed H1 interlayer.A new third-generation Ni-based superalloy T1 powder was mixed with H1 powder as another interlayer to improve the mechanical properties of the bonded joints.The res-ults show that,such a designed H1 interlayer is beneficial to the improvement of shear strength of DD5 alloy bonded joints by adjusting the bonding temperature and the prolongation of holding time.The maximum shear strength at room temperature of the joint with H1 interlayer reached 681 MPa when bonded at 1260℃for 3 h.The addition of T1 powder can effectively reduce holding time or relatively lower bond-ing temperature,while maintaining relatively high shear strength.When 1 wt.%T1 powder was mixed into H1 interlayer,the maximum room temperature shear strength of the joint bonded at 1260℃reached 641 MPa,which could be obtained for only 1 h.Considering the bonding temperature and the efficiency,the acceptable process parameter of H1+5 wt.%T1 interlayer was 1240℃/2 h,and the room tem-perature shear strength reached 613 MPa.
基金This work was financially supported by the National Nature Science Foundation of China(Grant No.61673222)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.23KJB430036)Wuxi University Research Start-up Fund for Introduced Talents(Grant No.2022r036).
文摘High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bonding strength reaches a maximum of 6.2 MPa.In addition,a thermal stress model for GaAs/Si wafers is established based on finite element analysis to obtain the distribution of equivalent stress and deformation variables at different temperatures.The shape varia-tion of the wafer is directly proportional to the annealing temperature.At an annealing temperature of 400℃,the maximum protrusion of 4 inches GaAs/Si wafers is 3.6 mm.The interface of GaAs/Si wafers is observed to be dense and defect-free using a transmission electron microscope.The characterization of interface elements by X-ray energy dispersion spectroscopy indi-cates that the elements at the interface undergo mutual diffusion,which is beneficial for improving the bonding strength of the interface.There is an amorphous transition layer with a thickness of about 5 nm at the bonding interface.The preparation of Si-based GaAs heterojunctions can enrich the types of materials required for the development of integrated circuits,improve the performance of materials and devices,and promote the development of microelectronics technology.
基金financially supported by the National Natural Science Foundation of China(Grant No.51972130)the Startup Fund of Huazhong University of Science and Technologythe Director Fund of Wuhan National Laboratory for Optoelectronics
文摘Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical design.In this work,we report two designed hybrid copper(I)iodides,(Ph_(3)MeP)_(2)Cu_(4)I_(6)and(Cy_(3)MeP)_(2)Cu_(4)I_(6),as blue-light-excitable yellow phosphors with ultrabroadband emission.In these compounds,the[Cu_(4)I_(6)]^(2-)anion forms an I6 octahedron centered on a cationic Cu_(4)tetrahedron.The strong cation-cation bonding within the unique cationic Cu_(4)tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)iodides.The ultrabroadband emission is attributed to the coexistence of free and self-trapped excitons.The WLED using the[Cu_(4)I_(6)]^(2-)anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W^(-1)and a high color rendering index of 88.This work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.
基金Intelligent Manufacturing and Robot Technology Innovation Project of Beijing Municipal Commission of Science and Technology and Zhongguancun Science and Technology Park Management Committee,Grant/Award Number:Z221100000222016National Natural Science Foundation of China,Grant/Award Number:62076014Beijing Municipal Education Commission and Beijing Natural Science Foundation,Grant/Award Number:KZ202010005004。
文摘Non-destructive detection of wire bonding defects in integrated circuits(IC)is critical for ensuring product quality after packaging.Image-processing-based methods do not provide a detailed evaluation of the three-dimensional defects of the bonding wire.Therefore,a method of 3D reconstruction and pattern recognition of wire defects based on stereo vision,which can achieve non-destructive detection of bonding wire defects is proposed.The contour features of bonding wires and other electronic components in the depth image is analysed to complete the 3D reconstruction of the bonding wires.Especially to filter the noisy point cloud and obtain an accurate point cloud of the bonding wire surface,a point cloud segmentation method based on spatial surface feature detection(SFD)was proposed.SFD can extract more distinct features from the bonding wire surface during the point cloud segmentation process.Furthermore,in the defect detection process,a directional discretisation descriptor with multiple local normal vectors is designed for defect pattern recognition of bonding wires.The descriptor combines local and global features of wire and can describe the spatial variation trends and structural features of wires.The experimental results show that the method can complete the 3D reconstruction and defect pattern recognition of bonding wires,and the average accuracy of defect recognition is 96.47%,which meets the production requirements of bonding wire defect detection.
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFA0707300)the Key Research and Development Program projects of Shandong(No.2020CXGC010304).
文摘This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 Pa.Non-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into MgO.In addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the interface.This process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.
基金National Natural Science Foundation of China(U22B20131)for supporting this project.
文摘Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.
基金financially supported by the National Natural Science Foundation of China(Grant No.21905033,52271201)the Key Research and DevelopmentProgram of Sichuan Province(Grant No.2022YFG0100)+1 种基金the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(Grant No.2022ZYD0045)the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization(Grant No.2020P4FZG02A)
文摘The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.
基金Supported by Innovation and Technology Fund (No.ITP/045/19AP)Commercial Research&Development (CRD) Funding Supported by Hong Kong Productivity Council (No.10008787)。
文摘We put forward a method of fabricating Aluminum(Al)/carbon fibers(CFs) composite sheets by the accumulative roll bonding(ARB) method. The finished Al/CFs composite sheet has CFs and pure Al sheets as sandwich and surface layers. After cross-section observation of the Al/CFs composite sheet, we found that the CFs discretely distributed within the sandwich layer. Besides, the tensile test showed that the contribution of the sandwich CFs layer to tensile strength was less than 11% compared with annealed pure Al sheet. With ex-situ observation of the CFs breakage evolution with-16%,-32%, and-45% rolling reduction during the ARB process, the plastic instability of the Al layer was found to bring shear damages to the CFs. At last, the bridging strengthening mechanism introduced by CFs was sacrificed. We provide new insight into and instruction on Al/CFs composite sheet preparation method and processing parameters.
文摘One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.
基金supports from the National Natural Science Foundation of China(Nos.52075472,52004242)the National Key Research and Development Program of China(No.2018YFA0707300)the Natural Science Foundation of Hebei Province,China(No.E2020203001)。
文摘TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding,thereby promoting the formation of an effective mechanical interlock at the interface,which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates.Moreover,the composite plate subjected to oxidation treatment exhibited high shear strength,particularly at a 43%reduction rate,achieving a commendable value of 117 MPa.Based on oxidation treatment and different reduction rates,the annealed composite plates at temperatures of 400,450,and 500°C displayed favorable resistance to interface delamination,highlighting their remarkable strength-plasticity compatibility as evidenced by a maximum elongation of 31.845%.
文摘This year,Toray Industries,Inc.,announced that it has developed an insulating resin material for hybrid bonding(micro bonding).The material is based on Semicofine™and Photoneece™.These are high-heat-resistant polyimide coatings for semiconductor and display devices.The new material combines a conventional polyimide coating agent with the company’s processing and bonding technologies.It can enhance the yields and reliability of semiconductor devices in the hybrid bonding process,which entails bonding semiconductor chips with metal electrodes.Toray will push ahead with prototyping and providing samples to customers.It aims to obtain materials certification in 2025 and start mass production by 2028.
基金Scientific Research Fund of Hunan Provincial Education Department(21A0123)。
文摘In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete.The effects of steel corrosion rate,steel bar diameter,steel bar strength grade,and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed.The influence of different corrosion rates on specimens’bonding strength and bond-slip curves was determined,and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed.The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate.Additionally,an increase in corrosive crack width leads to a linear decrease in bonding strength.Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible.Furthermore,a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values,which aligned well with the experimental findings.
文摘In this work,the ultrasonic assisted active metal soldering of SiO_(2) glass and Al was successfully achieved using Sn-2Ti solder filler at a low soldering temperature of 250℃in ambient atmosphere.A nano-crystallineα-Al2O3 layer with the average thickness of 13.9 nm and a nano-crystalline R-TiO_(2) layer with the average thickness of 16.2 nm are formed at the interface of Al/Sn and SiO_(2)/Sn respectively because Al elements did not diffuse from Al alloy side to SiO_(2) side,which verified that a sono-oxidation reaction had occurred during the ultrasonic assisted active metal soldering process.The soldered butt joints exhibited an average tensile strength of 25.31 MPa.
基金Funded by National Natural Science Foundation of China(Nos.U21A20149 and 51878003)。
文摘To evaluate various interlaminar bonding reinforcement techniques used for steel bridge decks,the UHPC surface was roughened with shot blasting(SB),transverse grooving(TG)and surface embedded stone(S),epoxy resin(E),epoxy asphalt(EA)and high viscosity high elasticity asphalt(HV)as interlayer bonding materials.In addition,a diagonal shear test was conducted using a self-designed diagonal shear jig.The effects of adhesive layer materials type,surface texture type,and different loading rates on the interlaminar bonding performance of UHPC/SMA combination specimens were investigated.The experimental study showed that the peak shear strength and shear modulus of the combined specimen decreased gradually with the decrease of thermosetting of the adhesive layer materials.The peak shear fracture energy of E was greater than that of HV and EA.The synergistic effect of the contact force generated by the roughing of the UHPC surface,the friction force,and the bonding force provided by the adhesive layer material can significantly improve the interlaminar shear performance of the assemblies.The power-law function of shear strength and shear modulus was proposed.The power-law model of peak shear strength and loading rate was verified.The shear strength and predicted shear strength satisfy the positive proportional functions with scale factors of 0.985,1.015,0.961,and 1.028,respectively.
基金Supported by National Natural Science Foundation of China(Grant Nos.51275438,51405421)Hebei Provincial Natural Science Foundation of China(Grant No.E2015203101)
文摘Dynamic modeling of a parallel manipulator(PM) is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.
基金supported by Research Foundation funded by Thu Dau Mot University。
文摘Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.
基金supported by Ministry of Science and Technology(2018YFA0208504)the Beijing Natural Science Foundation(JQ21006,2212045)+6 种基金National Natural Science Foundation of China(92163128,52073016)supported by the Fundamental Research Funds for the Central Universities(buctrc201828,XK1802-2)Open Project of State Key Laboratory of Organic-Inorganic Composites(oic-202201006)Open Project of State Key Laboratory of Supramolecular Structure and Materials(sklssm2023010)L.Ding thanks the National Key Research and Development Program of China(2022YFB3803300)the open research fund of Songshan Lake Materials Laboratory(2021SLABFK02)he National Natural Science Foundation of China(21961160720).
文摘Insulating polymers are characterized by a predominantlyσ-covalent structure,which localize electrons in the atoms and exhibit dielectricity.Insulating polymers typically adopt a more linear and extended conformation,as the repeating units are connected by single covalent bonds,resulting in a relatively straight and extended chain structure.For most insulating polymers,the contour length(L_(c))is significantly larger than their persistence length(Lp)due to the rotation of C−C single bonds(Fig.1(a)).Consequently,this leads to a flexible,random-coil chain conformation.This structural feature contributes to the great mechanical durability and resistance to crack initiation during stretching or bending processes.In contrast,conjugated polymers possess aπ-conjugated molecular structure,allowing electron mobility along the main chain,called delocalization,which imparts semiconducting properties[1,2].The presence of rigid,alternating single and multiple bonds results in comparable Lc and Lp,thereby yielding a stiff or semi-flexible conformation(Fig.1(b))[3,4].As a consequence,most conjugated polymers are prone to fracture under low strain levels(<10%)[5−7].
文摘Background: Bonding disorders affect the growth and development of infants. In Japan, the Japanese version of the Mother-to-Infant Bonding Scale (MIBS-J) is widely used for early detection of bonding disorders. Repeated use of a questionnaire has problems of reduced validity. In order to correctly detect bonding disorders at multiple time points, it is necessary to confirm the measurement invariance of the scale. Baba et al. reported that invariance of the MIBS-J factor structure could only be obtained by abridging the scale into three items. Purpose: The aim of this study was to 1) confirm the factor structure and measurement invariance of the MIBS-J between two measurement times and 2) to examine factors that can be used without being affected by measurement time in order to identify item that contribute to measure met invariance. Methods: We analysed the data of 1049 and 878 mothers with a neonate collected in two waves: 5 days (Wave 1) and 1 month postpartum (Wave 2). Exploratory and confirmatory factor analyses were conducted on the data randomly divided into two groups in each wave. Results: The three-item model (MIBS-J items 1, 6, and 8) was most accepted. Measurement invariance and structural invariance were confirmed in the model. This was consistent with Baba et al.’s model. Conclusion: The three MIBS-J items showed measurement invariance and structural invariance in Japanese mothers during 1 month postpartum.