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  • 1
    Electronic Resource
    Electronic Resource
    Fabrication and Characteristics of Carbon Fiber Reinforced C–SiC Dual Matrix Composites (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 145-148 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A series of carbon fiber reinforced C-SiC dual matrix composites (C/C-SiC composites)were developed through precursor infiltration of polycarbosilane (PCS) and pyrolysis (PIP), usingporous C/C composites with different density from chemical vapor infiltration (CVI) as thepreform. The density, mechanical properties, and microstructure of the composites wereinvestigated and the effects of the preform density and the PCS concentration of the infiltrationsolution on the final density and the mechanical properties of the composites were discussed indetail. The results show that the final density of the C/C-SiC composites prepared at the infiltrationconcentration of 50% is the highest, indicating that 50% is the proper PCS concentration of thePCS/ Xylene solution to prepare the C/C-SiC composites. The final densities of C/C-SiC compositeswere closely related to the preform density and the highest final density corresponds to the highestoriginal preform density. For the composites prepared using infiltration solution of 50% PCS, theC/C-SiC composite whose preform density is 1.23 g/cm3 possesses the best mechanical propertieswhile that whose preform density is 1.49 g/cm3 the worst mechanical properties
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.334-335.145.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical Properties of Hot Press Sintered NASICON Ceramics (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 149-152 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Sodium superionic conductor, NASICON ceramic (Na1+xZr2SixP3-xO12, x=2), washot-press sintered under different temperatures and the electrical properties of the obtained differentsamples were investigated. Results show that the relative density of the ceramics can be improvedby hot-press process efficiently and the crystal size of the samples are closely related to sinteringtemperature. With the increase of sintering temperature, both the density and the crystal size ofsamples increase obviously, resulting in the increase of ionic conductivity of samples as thesintering temperature. When the sintering temperature reaches 1150oC, the ionic conductivity ofsample is as high is 3.6×10-3S/cm, which is obviously higher than that of sample sintered at 1000oC(2.13×10-3S/cm). As the frequency increase, the real parts and the imaginary parts of complexdielectric constants for all the samples decrease in 8.2 GHz~12.4GHz frequency band. The ceramicsobtained at the higher temperature possess the higher dielectric constant
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.334-335.149.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation and Microwave Permittivity of SiC-AlN Solid Solution Powders (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 310-312 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: SiC-AlN solid solution powders were prepared from the mixtures of aluminum, silicon andcarbon black in a nitrogen atmosphere with preheating self-propagating high temperature synthesis (SHS)method. The powders synthesized with different ratios of Al/Si were mixed with paraffin wax and themicrowave permittivity of the mixtures was measured at the frequency of 8.2~12.4GHz. The results werecontrasted with that of SiC powders synthesized by preheating SHS in argon and nitrogen atmosphererespectively. The ε′, ε″, and the tgδ (ε″/ε′) of the mixture of SiC prepared in a nitrogen atmosphere arehighest, followed with those of the SiC-AlN solid solution powders and the SiC powders prepared in anargon atmosphere. Along with the increase of atomic ratio of Al/Si, the ε′, ε″, and tgδ of SiC-AlN solidsolution decrease. We believe that, with the increase of AlN dissolved, the concentration of carriers andthe effect of dielectric relaxation will decrease because of the two contrary dopants
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.310.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Microstructure and Effective Modeling of the Microwave Permittivity of Nano SiC(N) Composite Powder (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 11-12 (Feb. 2006), p. 141-144 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The nano SiC(N) composite powder was synthesized from hexamethyldisilazane((Me3Si)2NH) (Me:CH3) by a laser−induced gas-phase reaction. The microwave permittivity of thenano SiC(N) composite powder and paraffin wax (or other dielectric materials) composites can betailored by the content of this nano powder. The dissipation factors (tgδ) of the nano SiC(N)composite powder are high at the microwave frequencies. And ε′, ε″ and tgδ of composites increasewith the volume filling factor (v) of nano SiC(N) powder. The nano SiC(N) composite powderwould be a good candidate for microwave absorbing material and electromagnetic interface (EMI)shielding material. The classical effective medium functions can not effectively model themicrowave permittivities of the SiC(N) nanocomposites. We found that the microwavepermittivities of the nanocomposites can be effectively modeled using second-order polynomials.These polynomials are dependent only on the filling factor and are purely mathematical models.The ε′ and ε″ of nanocomposites can be effectively modeled using second-order polynomials (ε′,ε″=Av2+Bv+C)
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.11-12.141.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Dielectric Properties of Hot-Pressed of SiCN/A〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 Nanocomposites (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 697-700 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A series of nanocomposites, SiCN/A3S2 ceramics, were prepared by hot-pressing method.The nanometer SiCN powder is characterized of high dielectric dissipation. The dielectricproperties of the SiCN/A3S2 nanocomposites were investigated. XRD and SEM were conducted tostudy the phases and microstructure of the nanocomposites. Compared with the pure A3S2 ceramic,the grain size in the nanocomposites is reduced due to the addition of nanometer SiCN powder. Therelative densities of the nanocomposites are also lower than that of the pure A3S2 ceramic. Both thereal and imaginary parts of the complex permittivity of nanocomposites in X band increase as thecontent of SCN powder in the samples rises obviously. When the contents of SiCN powder insamples are same, the real and imaginary parts of the samples vary with the sintering temperature.The tanδ of the nanocomposites reduces from 1.9 to 1.4 when sintering temperature increases from1450OC to 1650 OC. SAED pattern reveals that structure of the SiCN in SiCN/ A3S2 sintered athigher temperatures tend to crystallize. The real, imaginary parts and dissipation factor of thenanocomposites sintered at higher temperature is lower than those sintered at 1450 °C
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.334-335.697.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Microwave Dielectric Property of Porous Silicon Nitride Ceramics (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 307-309 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper presents the microwave dielectric property of porous silicon nitride ceramics at afrequency of 9360 MHz, which were fabricated by the nitridation of silicon powder. The porous ceramicswith different volume fraction of porosity from 18.6% to 56.2% were produced by adding differentamount of the pore-forming agent into the initial silicon powder. Microstructural analysis revealed adense matrix containing large pores and cavities with needle-shaped and flaky β-Si3N4 grains distributingin it. The results showed that the dielectric constant of the ceramics reduces with the porosity increases.With the addition of α-Si3N4 powder in the raw silicon powder, the nitridation rate is raised, and thedielectric constant and the dielectric loss of the ceramics decrease notablely
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.307.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Microstructure and Mechanical Property of 3D Textile C/SiC Composites Fabricated by Chemical Vapor Infiltration (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 11-12 (Feb. 2006), p. 81-84 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Three dimensional textile carbon fiber reinforced silicon carbide (3D textile C/SiC)composites with pyrolytic carbon interfacial layer were fabricated by chemical vapor infiltration.The microstructure and mechanical property of 3D textile C/SiC composites were investigated. Athin pyrolysis carbon layer (0.2 ± μm) was firstly deposited on the surface of carbon fiber as theinterfacial layer with C3H6 at 850°C and 0.1 MPa. Methyltrichlorosilane (CH3SiCl3 or MTS) wasused for the deposition of the silicon carbide matrix. The conditions used for SiC deposition were1100°C, a hydrogen to MTS ratio of 10 and a pressure of 0.1 MPa. The density of the compositeswas 2.1 g cm-3. The flexural strength of the 3D textile C/SiC composites was 438 MPa. The 3Dtextile C/SiC composites with pyrolytic carbon interfacial layer exhibit good mechanical propertiesand a typical failure behavior involving fibers pull-out and brittle fracture of sub-bundle. The realpart (ε′) and imaginary part (ε″) of the complex permittivity of the 3D-C/SiC composites are51.53-52.44 and 41.18-42.08 respectively in the frequency range from 8.2 to 12.4 GHz. The3D-C/SiC composites would be a good candidate for microwave absorber
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.11-12.81.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and Mechanical Properties of C/C-SiC Composites (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1501-1504 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Porous C/C composite with certain porosity prepared by Chemical vapor infiltration(CVI) was chosen as the preforms to develop the C/C-SiC composites through precursor infiltrationand pyrolysis(PIP), using PCS (polycarbosilane) as the precursor and divinylbenzene as solvent andcross-linking reagent for PCS. The effect of the infiltration solution with different PCS/DVB ratio onthe final density, microstructure, and mechanical properties of composites was investigated and theproper PCS/DVB ratio to prepare the C/C-SiC composites was suggested. The experimental resultsshowed that the final densities and the mechanical properties of the composites were close related tothe PCS/DVB ratio. Higher PCS/DVB ratio resulted in higher final density and better mechanicalproperties, but not the highest PCS/DVB ratio could get the best mechanical properties. The mainreason is that too high PCS/DVB ratio will make the infiltration process become difficult and lead tothe formation of lots of pores in the final composite, at last lowers the mechanical properties. It isbelieved that the 50% PCS content is proper to prepare the C/C-SiC composites. The composite from50% PCS infiltration solution could get the final density of1.696g/cm3, the flexural strength of171Mpa, and shearing strength of 21.6Mpa, which are the best mechanical results among the obtainedmaterials
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/16/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.546-549.1501.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanical and Microwave Dielectric Properties of C〈sub〉sf〈/sub〉/Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 Composites (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1661-1664 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power,short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 wasalmost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed thatspecial network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, andfracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% thecarbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at afrequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of thepermittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbonfibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/16/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.546-549.1661.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Unsupervised Learning of Higher-Order Statistics (1999)
    Springer
    Neural processing letters 9 (1999), S. 249-255 
    Details
    ISSN: 1573-773X
    Keywords: unsupervised learning ; high-order statistics ; adaptive signal processing ; blind signal processing ; tensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper deals with the adaptive extraction of higher-order statistics of related signals. We will show how to use higher-order neural networks to adaptively extract the higher-order cumulant matrices and tensors with an invariant weight norm. This proposed scheme can serve as an alternative tool in many application fields with higher-order statistics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018608005199
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