High-purity and high-yield boron nitride nanotubes with large aspect ratio were prepared by a facile two-step process,including the synthesis of boron/nickel containing precursors by precipitation reactions and subseq...
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High-purity and high-yield boron nitride nanotubes with large aspect ratio were prepared by a facile two-step process,including the synthesis of boron/nickel containing precursors by precipitation reactions and subsequent thermally catalytic chemical vapor deposition *** influence of catalyst content and annealing temperature on the phase composition and microstructure of the products were *** results show that it is difficult to exert the catalytic effect of nickel-based catalyst at low temperatures(<1400℃).At appropriate temperatures(1400-1500℃),highly crystalline boron nitride nanotubes with a length of more than 50 mm and a diameter of 50 nm are *** content of catalyst in the precursor mainly affects the morphology of the boron nitride *** the content is too low,it is easy to form boron nitride particles;while high catalyst content can easily lead to catalyst aggregation and form a submicron one-dimensional boron nitride with unregular *** on microstructural evolutions,phase changes,and thermodynamic analysis,the vapor-liquid-solid(V-L-S)growth mechanism of the tip growth mode dominates the formation of boron nitride nanotubes has also been verified.
Amorphous alloys without crystalline defects(dislocation,crystal boundary)are ideal hydrophobic coating materials due to their low surface *** work used a synergistic method of detonation spraying and surface modifica...
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Amorphous alloys without crystalline defects(dislocation,crystal boundary)are ideal hydrophobic coating materials due to their low surface *** work used a synergistic method of detonation spraying and surface modification to obtain the superhydrophobic Febased amorphous coatings with high hardness and dense structure on the Q 235 *** results showed that the water contact angles(WCA)of the superhydrophobic coating was 160°±3.6°,and water droplets could bounce off the superhydrophobic coating surface,illustrating the excellent self-cleaning performance of ***,the corrosion current density(i_(corr))of the superhydrophobic coating further decreased by 2 orders of magnitude down to8.008×10^(-8)A·cm^(-2)compared to the as-deposited coating with 5.473×10^(-6)A·cm^(-2);the corrosion potential(E_(corr))of the superhydrophobic coating shifted by 34 mV to the positive side compared with that of the as-deposited coating(-310 mV).Likewise,the impedance modulus|Z|values of the superhydrophobic coating increased by nearly2 orders of magnitude up to 1×10^(5.6)compared to the asdeposited coating with 1×10^(3.8).Even through lasting immersion in NaCl for 10 days,|Z|values of the superhydrophobic coating were still much higher than those of the as-deposited *** superhydrophobic Fe-based amorphous coatings could respond to their applications under extreme conditions due to their excellent hydrophobicity and self-cleaning properties,illustrating their promising future in aerospace,automotive,and machinery industries.
Semiconductors can generate excited charge carriers for photo-or electro-chemical reactions such as water splitting for H2 ***,the dynamic charge-transfer process has been directly observed to reveal the photocatalyti...
Semiconductors can generate excited charge carriers for photo-or electro-chemical reactions such as water splitting for H2 ***,the dynamic charge-transfer process has been directly observed to reveal the photocatalytic mechanism.
In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound *...
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In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound *** effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first *** demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 *** 10μm’s Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds(IMCs)at the interface zone of the AZ91D/A356 bimetal,while the Ni coating with the thickness of 45μm and 190μm can avoid the formation of the Al-Mg *** the Ni coating was 45μm,the Ni coating disappeared and transformed into Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles at the interface *** a thickness of 190μm’s Ni coating,part of the Ni coating remained and the interface layer was composed of the Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles,Mg_(2)Ni layer,Ni solid solution(SS)layer,Al_(3)Ni_(2) layer,Al_(3)Ni layer and sporadic Al_(3)Ni+Al-Al_(3)Ni eutectic structures from AZ91D side to A356 side in *** interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg *** shear strength of the AZ91D/A356 bimetal with a Ni coating of 45μm thickness enhanced 41.4%in comparison with that of the bimetal without Ni coating,and the fracture of the bimetal with 45μm’s Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.
Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been ***,the current reports about TPMS porous structures highly rely ...
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Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been ***,the current reports about TPMS porous structures highly rely on the implicit equation,which limited the design *** this work,novel shell-based TPMS structures were designed and fabricated by laser powder bed *** comparisons of manufacturability,mechanical properties,and shape recovery responses between traditional solid-based and novel shell-based TPMS structures were *** indicated that the shell-based TPMS porous structures possessed larger Young's moduli and higher compressive ***,Diamond shell structure possessed the highest Young's moduli of 605.8±24.5MPa,while Gyroid shell structure possessed the highest compressive strength of 43.90±3.32 *** addition,because of the larger specific surface area,higher critical stress to induce martensite transformation,and lower austenite finish temperature,the Diamond shell porous structure exhibited much higher shape recovery performance(only 0.1%residual strain left at pre-strains of 6%)than other porous *** results substantially uncover the effects of structural topology on the mechanical properties and shape recovery responses of NiTi shape memory alloy scaffolds,and confirm the effectiveness of this novel structural design *** research can provide guidance for the structural design application of NiTi porous scaffolds in bone implants.
Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine ***,the tradeoff between their high sensitivity and wide response range remains ...
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Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine ***,the tradeoff between their high sensitivity and wide response range remains a *** by human skin,we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube(CNT)/polydimethylsiloxane(PDMS)composite film with a hierarchical structured surface(h-CNT/PDMS)through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane(PU)scotch tape to obtain an h-CNT/PDMS-based flexible pressure *** on in-situ optical images and finite element analysis,the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range(0.1661 kPa^(-1),0.4574 kPa^(-1)and 0.0989 kPa^(-1)in the pressure range of 0–18 kPa,18–133 kPa and 133–300 kPa)compared with planar CNT/PDMS composite film(0.0066 kPa^(-1)in the pressure range of 0–240 kPa).The prepared pressure sensor displays rapid response/recovery time,excellent stability,durability,and stable response to different loading modes(bending and torsion).In addition,our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial *** study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.
Silver-based alloys are significant light-load electrical contact materials(ECMs).The trade-off between mechanical properties and electrical conductivity is always an important issue for the development of silver-base...
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Silver-based alloys are significant light-load electrical contact materials(ECMs).The trade-off between mechanical properties and electrical conductivity is always an important issue for the development of silver-based *** this paper,we proposed an idea for the regulation of the mechanical properties and the electrical conductivity of Ag-11.40Cu-0.66Ni-0.05Ce(wt%)alloy using in-situ composite *** alloy was processed using rolling,heat treatment,and heavy drawing,the strength and electrical conductivity were tested at different deformation stages,and the microstructures during deformation were observed using field emission scanning electron microscope(FESEM),transmission electron microscope(TEM)and electron backscatter diffraction(EBSD).The results show that the method proposed in this paper can achieve the preparation of in-situ composite fiber-reinforced Ag-Cu-Ni-Ce *** the heavy deformation drawing,the room temperature Vickers hardness of the as-cast alloy increased from HV 81.6 to HV 169.3,and the electrical conductivity improved from 74.3%IACS(IACS,i.e.,international annealed copper standard)to 78.6%*** the deformation increases,the alloy strength displays two different strengthening mechanisms,and the electrical conductivity has three stages of *** research provides a new idea for the comprehensive performance control of high-performance silver-based ECMs.
Designing highly efficient photocatalyst for hydrogen peroxide(HO)production is an ideal strategy to avoid the shortcomings of traditional HOproduction and to realize the conversion of solar energy to chemical *** thi...
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Designing highly efficient photocatalyst for hydrogen peroxide(HO)production is an ideal strategy to avoid the shortcomings of traditional HOproduction and to realize the conversion of solar energy to chemical *** this work,a step-scheme(S-scheme)heterojunction photocatalyst composed of Zn O and WOis carefully prepared by hydrothermal and calcination method for efficient photocatalytic *** ZW30 composite photocatalysts exhibit enhanced activity with the highest HO-production rate of 6788μmol *** results show that the photocatalytic HOproduction process is dominated by a direct two-electron Oreduction *** enhanced photocatalytic HO-production activity is attributed to the formation of interfacial internal electric field(IEF)in the S-scheme heterojunction,which boosts the spatial separation of charge carriers and enables electrons with the strongest reduction power to participate in *** work provides an in-depth insight of the great advantages of S-scheme heterojunction in photocatalytic HOproduction.
Because the amorphous/amorphous nano-laminates could enhance signifcantly the mechanical properties of the amorphous materials,they have been widely studied as a new group of structural *** this study,the nano-scratch...
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Because the amorphous/amorphous nano-laminates could enhance signifcantly the mechanical properties of the amorphous materials,they have been widely studied as a new group of structural *** this study,the nano-scratch performance of the Cu_(80)Zr_(20)/Cu_(20)Zr_(80)(A/B-type)and the Cu_(20)Zr_(80)/Cu_(80)Zr_(20)(B/A-type)amorphous/amorphous nano-laminates was evaluated by molecular dynamics *** dependences on the type of indenter,layer thickness,stacking mode and scratch depth were systematically *** is a signifcant size effect for the tribological properties of amorphous/amorphous nanolaminates that the friction force of the A/B-type increases with the increase of layer thickness,but the friction force of the B/A-type decreases as the layer thickness *** interface has an obvious obstruction effect on the shear deformation and reduces the plastic affected region below the scratched ***,the contact environment of the indenter bottom has an important influence on the normal force,so it’s not that the deeper the depth,the greater the normal *** it should not be ignored when evaluating the tribological properties of the amorphous/amorphous *** work can deepen the understanding of hetero-interface on the deformation mechanism during nano-scratch,and help to design amorphous nano-laminates with tailored tribological performance for practical applications.
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