BaCO3 whiskers exhibiting different morphologies were fabricated by a simple precipitation reaction of barium ch/oride with sodium carbonate in the absence and presence of poly-（styrene-alt-maleic acid） （PSMA） as ...
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BaCO3 whiskers exhibiting different morphologies were fabricated by a simple precipitation reaction of barium ch/oride with sodium carbonate in the absence and presence of poly-（styrene-alt-maleic acid） （PSMA） as a crystal growth modifier at room temperature. The as-prepared products were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. The influences of experimental parameters on the size and morphology of BaCO3 whiskers were investigated and discussed. It was found that the as-prepared BaCO3 whiskers are single crystals with diameter ranging from 100 to 300 run, and grow along the crystallographic a-axis or [100] direction. BaCO3 whiskers with different morphologies, such as branching and dendritic structure, can be obtained depending on the experimental conditions. With increasing PSMA concentration, the diameter of BaCO3 whiskers decreases.
The thermal shock resistance and anti- aluminum erosion of TiB2 - BN multiphase ceramics composites were studied. The experimental results show that the TiB2-BN multiphase ceramic possesses a good thermal shock resist...
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The thermal shock resistance and anti- aluminum erosion of TiB2 - BN multiphase ceramics composites were studied. The experimental results show that the TiB2-BN multiphase ceramic possesses a good thermal shock resistance at high temperatures （ 1000, 1200, 1400, 1500 ℃ ）, with the increasing in thermal shocking temperature, the electro-conductivity of TiB2-BN ceramics increases. The metal aluminum has a great influence on the properties of TiB2 - BN ceramics and the main reason is that the aluminum reacts seriously with BN. It is suggested that the content of BN should be reduced to the greatest extent.
Nanocrystalline WC-Co composite powder and coated tungsten diamond by using vacuum vapor deposition were consolidated by the spark plasma sintering （SPS） process to prepare diamond-enhanced WC-Co cemented carbide co...
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Nanocrystalline WC-Co composite powder and coated tungsten diamond by using vacuum vapor deposition were consolidated by the spark plasma sintering （SPS） process to prepare diamond-enhanced WC-Co cemented carbide composite materials. The interface microstructures between coated tungsten diamond and WC-Co cemented carbide matrix were investigated by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）. The results showed that there is a transitional layer between the diamond and the matrix, in which the carbon content is 62.97wt.%, and the content of cobalt in the transitional zone is 6.19wt.%; the content of cobalt in the WC-Co cemented carbide matrix is 6.07wt.%, in which the carbon content is 15.95wt.%, and the content of cobalt on the surface of diamond is 7.30wt.%, in which the carbon content is 80.38wt.%. The transitional zone prevents the carbon atom of the diamond from spreading to the matrix, in which the carbon content does coincide with the theoretical value of the raw nanocomposite powders, and the carbon content forms a graded distribution among the matrix, transitional zone, and the surface of diamond; after the 1280℃ SPS consolidated process the diamond still maintains a very good crystal shape, the coated tungsten on the surface of the diamond improves thermal stability of the diamond and increases the bonding strength of the interface between the diamond and the matrix.
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics we...
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A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.
Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using ＂FeSO4 solution-sodium caprylate-Decanol＂ 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft ...
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Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using ＂FeSO4 solution-sodium caprylate-Decanol＂ 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft templates and the synthesized iron ,fibers were characterized by polarizing microscopy, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray microanalysis etc. The experimental results shou that the synthesized iron fibers with a crystal phase grew up in the form of fiber clusters of about 200 nm along the direction perpendicular to the cathode surface. Each cluster was composed of several tens of fibers. The fibers had almost the same length of more than 10μm with a diameter of about 50 nm.
A physical model for mobility degradation by interface-roughness scattering and Coulomb scattering is proposed for SiGe p-MOSFET with a high-k dielectric/SiO2 gate stack. Impacts of the two kinds of scatterings on mob...
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A physical model for mobility degradation by interface-roughness scattering and Coulomb scattering is proposed for SiGe p-MOSFET with a high-k dielectric/SiO2 gate stack. Impacts of the two kinds of scatterings on mobility degradation are investigated. Effects of interlayer (SiO2) thickness and permittivities of the high-k dielectric and interlayer on carrier mobility are also discussed. It is shown that a smooth interface between high-k dielectric and interlayer, as well as moderate permittivities of high-k dielectrics, is highly desired to improve carriers mobility while keeping a low equivalent oxide thickness. Simulated results agree reasonably with experimental data.
WC- 10Co nanocomposite powder produced by spray pyrolysis-continuoas reduction and carbonization technology was used, and the vacuum sinteriag plus sinterhip process was cdopted to prepare ultrafine WCCo cemented carb...
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WC- 10Co nanocomposite powder produced by spray pyrolysis-continuoas reduction and carbonization technology was used, and the vacuum sinteriag plus sinterhip process was cdopted to prepare ultrafine WCCo cemented carbide. The microstructure, grain size, porosity, density, Rockwell A hardness （ HRA ）, transverse rupture strength （ TRS ） , saturated magnetization and coercivity force were studied. The experimental results show that average grain size of the sample prepared by vacuum sintering plas sinterhip technology was about 420 nm, transverse rupture strength was more than 3460 MPa, and Rockwell A hardness of sintered specimen was more than 92.5. Ultrafine WC- 10Co cemented carbide with high strength and high hardness is obtained.
Yttrium-filled sku, tterudites Yy Fex Co4-x Sb12 （ Y =0- 0. 40 ） were synthesized. The effect of Y filling fraction on thermoelectric properties of Yy Fex Co4-x Sb12 was investigated. All samples showed p-type condu...
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Yttrium-filled sku, tterudites Yy Fex Co4-x Sb12
（ Y =0- 0. 40 ） were synthesized. The effect of Y filling fraction on thermoelectric properties of Yy Fex Co4-x Sb12
was investigated. All samples showed p-type conduct. The electrical conductivity decreased with increasing filling fraction y. The Seebeck coefficient inreased with increasing temperature. The lattice thermal conductivity decreased with increasing filling fraction y and showed the minimum value at a certain filling fraction y = 0.3. The effect of different filling atoms M（ M： Ba, Ce, Y） on the lattice thermal conductivity of MyFexCo4-xSb12 was discussed. The maximum ZT value of O. 7 was obtained for Y0.06 Fe0.7 Co3.3 Sb12 at 750 K.
The rods that were shaped from nanocrystalline WC- 10.21 Co-0.42 VC/ Cr3 C2 （ wt% ） composite powders by using powder extrusion molding （PEM） were investigated. The nanocrystalline WC- 10.21 Co- 0. 42 VC/ Cr3 C2 ...
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The rods that were shaped from nanocrystalline WC- 10.21 Co-0.42 VC/ Cr3 C2 （ wt% ） composite powders by using powder extrusion molding （PEM） were investigated. The nanocrystalline WC- 10.21 Co- 0. 42 VC/ Cr3 C2 （ wt% ） composite powders were prepared by the spray thermal decomposition-continuous reduction and carburization technology. In order to improve the properties of rods shaped by using powder extrusion molding, the cold isostatic pressing （CIP） technology was used before or after debinding. Specimens were siutered by vacuum siutering and hot isostatic pressing （HIP）. The density, Rockwell A hardness, magnetic coercivity , and magnetic saturation induction of siutered specimen were measured. The microstructure of the green bodies and the siutered specimens was studied by scanning electron microscopy （SEM）. Results show that the rod formed by using powder extrusion molding after debinding and followed by cold isostatic pressing can be siutered to 99.5% density of composite cemented carbide rods with an average grain size of about 200- 300 nm, magnetic coercivity of 30.4 KA / m, Rockwell A hardness of 92.6 and magnetic saturation induction of 85% . Superfine WC- 10 Co cemented carbide rods with excellent properties were obtained.
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