It is extremely difficult to incorporate and disperse nanoparticles (NPs), especially for a high percentage, into metal matrix during solidification processing to achieve crucial property enhancement in metal matrix n...
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ISBN:
(纸本)9781118888162
It is extremely difficult to incorporate and disperse nanoparticles (NPs), especially for a high percentage, into metal matrix during solidification processing to achieve crucial property enhancement in metal matrix nanocomposites (MMNCs), mainly due to the strong tendency of NP aggregation. Thus, the significant property enhancement expected by the addition of a high percentage of NPs is rarely achieved in solidification processing of bulk MMNCs. Here we show that an unprecedented uniform distribution of 5 vol.% SiC NPs in Mgl8Sn alloy matrix is obtained by solidification processing. The resulting Mgl8Sn matrix nanocomposites exhibits a very high microhardness value of 150 kg/mm2. The results reported in this work shed light on a potential pathway for production of ultrahigh performance metallic nanocomposites.
Compared with the conventional microcellular foaming injection molding, a novel technology named Supercritical fluid-laden pellet Injection molding Foaming Technology (SIFT), which havebeen developed recently, has a l...
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Compared with the conventional microcellular foaming injection molding, a novel technology named Supercritical fluid-laden pellet Injection molding Foaming Technology (SIFT), which havebeen developed recently, has a low equipment cost and good surface *** this study, the SIFT technology of PP/PC/PE-c-GMA was investigated and the mechanical properties, morphology and surface quality were *** experimental results show that the tensile strength of foamed componentis better than that of the solid componentwithout the packing pressure, and the surface quality is similar tothe solid *** can be concluded that the SIFT technology can be applied to manufacture the PP/PC/PE-c-GMA blends.
Colloids with anisotropic shape and properties can enable the assembly of advanced materials otherwise not attainable by microfabrication. In this study, we present a convenient method using common microfabrication to...
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Colloids with anisotropic shape and properties can enable the assembly of advanced materials otherwise not attainable by microfabrication. In this study, we present a convenient method using common microfabrication tools to generate a diverse array of non-spherical microparticles with well-defined shapes, sizes, electromagnetic properties for self-assembly applications. Projection photolithography onto SU-8 photoresist enabled the production of large aspect ratio microparticles such as cubes, cuboids, cylinders, hexagonal prisms, and parallelepipeds. We characterized these particles to confirm their anisotropic shape and size monodispersity. Fluorescent stains (e.g., Nile red) were mixed into the photoresist prepolymer to enhance the visualization of particle orientation. Particles designed for passive self-assembly were prepared by conventional photolithographic techniques. Particles designed for active assembly were then decorated with metallic patches in precise locations along the surface (e.g., top, side or multiple sides) using electron beam metal evaporation. This metal deposition process can enable orientational control of particles during their assembly in directed fields. After fabrication, large particles (e.g., 1,000 µm3) were released from the substrate via gentle sheer forces, whereas small particles (e.g., 10 µm3) were released by the dissolution of a sacrificial layer underneath the SU-8. Suspending the particles in water with surfactant (or other suitable solvents) provided amenable conditions for their assembly in static or dynamic systems. These conventional methods have the potential to catalyze new research in the fabrication and assembly of anisotropic patchy particles with controllable properties for the hierarchical development of self-assembled micromirrors, biosensors, and photonic crystals as examples.
A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styren...
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A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styrene/Cu （ABS/Cu） gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10^15 Ω at ABS rich side, while that declined to 10^5 Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vo1%- 4.74 vol% Cu content at Cu particles rich side. mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.
A resonance Raman study of graphene samples with different C13 isotopic concentrations and using different laser excitation energies is presented. The main Raman peaks (D, G, G*, and 2D) of graphene were measured and ...
A resonance Raman study of graphene samples with different C13 isotopic concentrations and using different laser excitation energies is presented. The main Raman peaks (D, G, G*, and 2D) of graphene were measured and the dependence of their frequencies on the isotope atomic mass follows a simple harmonic oscillator relation. The G* and 2D double-resonance peak positions were measured as a function of the laser energy, and we observed that the slopes of the laser energy dependence are the same independently of isotope concentration. This result shows that isotopic substitution does not alter the electron and phonon dispersions near the K point of the graphene Brillouin zone. From the linewidth of G and 2D Raman peaks, we have also obtained a dependence of the phonon lifetime on the C13 isotope concentration.
A layered structure of different copper oxides was produced by thermal oxidation of copper. The structure and microstructure of the different layers were investigated by scanning electron microscopy and transmission e...
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The aglycones of anthocyanidin dyes were previously reported to form carbinol pseudobase, cis-chalcone, and trans-chalcone due to the basic levels. The further investigations of ground and excited state properties of ...
The aglycones of anthocyanidin dyes were previously reported to form carbinol pseudobase, cis-chalcone, and trans-chalcone due to the basic levels. The further investigations of ground and excited state properties of the dyes were characterized using density functional theory with PCM(UFF)/B3LYP/6-31+G(d,p) level in the basic solutions. However, to the best of our knowledge, the theoretical investigation of their potential photosensitizers has never been reported before. In this paper, the theoretical photovoltaic properties sensitized by dyes have been successfully investigated including the electron injections, the ground and excited state oxidation potentials, the estimated open circuit voltages, and the light harvesting efficiencies. The results prove that the electronic properties represented by dyes’ LUMO-HOMO levels will affect to the photovoltaic performances. Cis-chalcone dye is the best anthocyanidin aglycone dye with the electron injection spontaneity of −1.208 eV, the theoretical open circuit voltage of 1.781 V, and light harvesting efficiency of 56.55% due to the best HOMO-LUMO levels. Moreover, the ethanol solvent slightly contributes to the better cell performance than the water solvent dye because of the better oxidation potential stabilization in the ground state as well as in the excited state. These results are in good agreement with the known experimental report that the aglycones of anthocyanidin dyes in basic solvent are the high potential photosensitizers for dye-sensitized solar cell.
The mechanical properties of Al alloys can be effectively enhanced with an addition of a low volume fraction of nano-sized reinforcements for numerous applications. However, it remains a great challenge for liquid pro...
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