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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
    Method for Estimating the Critical Cooling Rate for Glass Formation from Isothermal TTT Data (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1874-1877 
    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 method is proposed for estimating the critical cooling rate for glass formation and continuouscooling transformation curve (CCT) from isothermal TTT data. The critical cooling rates and CCT curvesfor a group of lithium disilicate glasses containing different amount of Pt as nucleating agent estimatedthrough this method are compared with the experimentally measured values and it shows this method cangive a reasonable estimation
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.1874.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
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and Microwave Permittivity of Nano-Sized Si/C/N Powder (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 3571-3574 
    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: Nano-sized Si/C/N powders are prepared from hexamethyldisilazane ((CH3)3Si)2NH) by chemical vapor deposition (CVD) at different pyrolysis temperatures from 900℃ to 1200℃. The as-formed Si/C/N nano powder is amorphous, and after controlled heat-treatment, SiC crystals formed. The composition of the Si/C/N powders prepared at different conditions is analyzed and the result shows that the nitrogen content of the Si/C/N powder is related to the synthesizing temperature. Si/C/N powders heat-treated at different temperatures are mixed with paraffin wax and the microwave permittivity of the mixture is measured. The result shows that the e¢, e², and the dissipation factor tg d ( e²/ e¢) of the mixture are high at the frequency of 8.2~12.4GHz, and thenitrogen content and the degree of crystallization have influence on the microwave permittivity. We believe that the high value of e¢, e² ,and tg d are due to the dielectric relaxation as the result of nitrogen atoms doped in silicon carbide lattice
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/10/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.475-479.3571.pdf
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