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  • 2005-2009  (8)
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Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Reactive Hot-Pressed Alumina–Boron Nitride Composites with Y2O3 Sintering Additive (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of Y2O3 addition (0–5 wt%) on the densification and properties of reactive hot-pressed alumina (Al2O3)–boron nitride composites based on the reaction between aluminum borate (2Al2O3·B2O3) and aluminum nitride (AlN) was investigated. The densification process was very sensitive to the amount of Y2O3. Compared with a low relative density of 79.3 theoretical density (TD)% for material with no Y2O3 addition, the material density reached 98.6 TD% with 0.25% Y2O3 addition. High Y2O3 additions resulted in the formation of a new phase Al5Y3O12. The grain growth of the Al2O3 matrix was promoted by the Y2O3 addition. Owing to the high density and the small Al2O3 particle size the sample with 0.25% Y2O3 addition demonstrated the highest bending strength of 540 MPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00437.x
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of Porous Si3N4 Ceramics with Rod-Shaped Pore Structure (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Porous Si3N4 ceramics were synthesized by pressureless sintering of green compacts prepared using slip casting of slurries containing Si3N4, 5 wt% Y2O3+2 wt% Al2O3, and 0–60% organic whiskers composed of phenol–formaldehyde resin with solids loading up to 60 wt%. Rheological properties of slurries were optimized to achieve a high degree of dispersion with a high solid-volume fraction. Samples were heated at 800°C in air and sintered at 1850°C in a N2 atmosphere. Porosities ranging from 0% to 45% were obtained by the whisker contents (corresponding to 0–60 vol% whisker). Samples exhibited a uniform pore distribution. Their rod-shaped pore morphology originated from burnout of whiskers, and an extremely dense Si3N4 matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00199.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Reaction Synthesized Boron Nitride-Containing Composites (BNCC) (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1385-1390 
    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: Based on the proposed inorganic reactions a series of high performance hexagonal boron nitride-containing composites (BNCC), include SiC-BN, Si3N4-SiC-BN, SiAlON-BN, AlN-BN, Al2O3-BN, AlON-BN and mullite-BN, have been prepared via reactive hot pressing or pressureless reactive sintering. Various boron-bearing components such as B, B4C, AlB2, SiB4, SiB6, B2O3 or H3BO3, 9Al2O3×2B2O3 (9A2B) and 2Al2O3×B2O3 (2AB) are used as the boron source. On the other hand, nitrogen gas or solid state nitirgen-bearing metal nitrides such as Si3N4 and AlN can be used as the nitrogen source. The in situ synthesized composites demonstrated homogeneous and isotropical microstructures with very fine (nano-sized) BN platelets or their agglomerates distributed in the matrixes. These composites showed high strength, low elasticity and improved strain tolerance. In this article the reaction design, thermodynamics, reaction mechanisms, reactive hot pressing or pressureless reactive sintering, microstructures and mechanical properties will be discussed
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.1385.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Pore Morphology on the Fabrication and Mechanical Properties of Porous Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 Ceramics (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1231-1236 
    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: Porous Si3N4 ceramics with different pore morphology have been fabricated, utilizing either organic whiskers or starch as the fugitive agents, through slip-casting and die-pressing technique, respectively. The obtained porous ceramics have rod shaped or equiaxial pore morphology, originated from there two kinds of pore forming agents. The mechanical properties were investigated. The strengthdecreased considerably when small amount of whiskers were added, however, further increase in the whisker content only cause a moderate decrease of the strength. Gas permeability were measured for the samples with high whisker content of 60 vol% (corresponding to porosity of about 45% in the sinteredbodies), and was compared with the counterpart contained the same porosity in which pores were equiaxial. The flexural strength of the samples with these two types of fugitive particles was almost the same, but the permeability of samples with rod-shaped pores were much higher than that with equiaxial pores, which can be understood in terms of a short pass model
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.1231.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructure and Tensile Properties of Oxide Dispersion Strengthened Molybdenum Alloys Prepared by Different Doping Process (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 481-484 
    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: The oxide lanthanum dispersion strengthened molybdenum alloys were prepared byproprietary powder metallurgy technology, in which the Mo-La2O3 powders were prepared byliquid-liquid doping process which the oxide lanthanum was added to ammonium bi-molybdatesolutions as aqueous solutions of La(NO3)3 and liquid-solid doping process which the oxidelanthanum was added to molybdenum oxide solid particles as aqueous solutions of La(NO3)3,respectively. The microstructure and tensile properties of the molybdenum alloys were investigated atroom temperature. The results show that the molybdenum alloys all have fine molybdenum grains,and the molybdenum alloy prepared by liquid-solid doping process mainly contain fine oxidelanthanum particles of submicron and nano-sized while the alloy prepared by liquid-liquid dopingprocess mainly contain nano-sized fine oxide lanthanum particles. The molybdenum alloys preparedby liquid-liquid doping process have higher yield strength and ductility than yield-solid dopingprocess. The results of strengthen mechanism analysis show that the high strength of themolybdenum alloys can be advisablely explained by the fine grain strengthening and particlesdispersion strengthening mechanism through the Hall–Petch relationship and Orowan model
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.481.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Reactive Synthesis and Mechanical Properties of ZrB〈sub〉2〈/sub〉-SiC-ZrC Composites (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 368-372 (Feb. 2008), p. 1758-1760 
    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: ZrB2-SiC based composites with 0,5 and 15 vol% addition of ZrC were synthesized via reactivehot pressing at 1800°C using Zr, Si and B4C as raw materials. The mechanical properties of thecomposites were investigated. The composite of ZSC15 that contained 15 vol% of ZrC has the highesthardness. ZSC5 with 5 vol% of ZrC owns a most homogenous microstructure and the highest fracturetoughness and flexural strength
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/56/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.368-372.1758.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Strengthening Effect of In-Situ Dispersed Hexagonal Boron Nitride in Ceramic Composites (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 317-318 (Aug. 2006), p. 163-166 
    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: High strength particulate ceramic composites are in general reinforced by strongdispersoids, such as strong ceramic particles (SiC, TiB2, ZrO2, et al) and strong metallic particles (Mo,W, et al). In this work high strength ceramic composites with in-situ synthesized hexagonal boronnitride (h-BN) have been prepared and characterized. As an example, we manufactured mullite-BNcomposites by reactive hot pressing (RHP) using aluminum borates (9Al2O3·2B2O3 and 2Al2O3·B2O3)and silicon nitride as starting materials. The obtained material RHPed at 1800°C showed a strength of540 MPa, which was 1.64 times higher than that of the monolithic mullite ceramics. TEM observationrevealed that the composite had an isotropic microstructure with a fine mullite matrix grain size ofless than 1 μm and a nano-sized h-BN platelets of about 200 nm in length and 60∼80 nm in thickness.The high strength was suggested to be from the reduced matrix grain size and the small tougheningeffect by the h-BN platelets. In addition, this kind of ceramic composite demonstrates low Young’smodulus that is beneficial to the thermal/mechanical shock resistance, and excellent machinability
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/51/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.317-318.163.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Ultra-High Temperature Ceramics (UHTCs) via Reactive Sintering (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1159-1163 
    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: Current high temperature ceramics, such as ZrO2, Si3N4 and SiC, cannot be used attemperatures over 1600°C due to their low melting temperature or dissociation temperature. For ultrahightemperature applications over 1800°C, materials with high melting points, high phase compositionstability, high thermal conductivity, good thermal shock and oxidation resistance are needed. Thetransition metal diborides, mainly include ZrB2 and HfB2, have melting temperatures of above 3000°C,and can basically meet the above demands. However, the oxidation resistance of diboride monolithicceramics at ultra-high temperatures need to be improved for the applications in thermal protectionsystems for future aerospace vehicles and jet engines. On the other hand, processing science for makinghigh performance UHTCs is another hot topic in the UHTC field. Densification of UHTCs at mildtemperatures through reactive sintering is an attracting way due to the chemically stable phasecomposition and microstructure as well as clean grain boundaries in the obtained materials. Moreover, thestability studies of the materials in phase composition and microstructures at ultra high applicationtemperatures is also critical for materials manufactured at relatively low temperature. Furthermore, theoxidation resistance in simulated reentry environments instead of in static or flowing air of ambientpressure should be evaluated. Here we will report the concept, advantages and some recent progress onthe reactive sintering of diboride–based composites at mild temperatures
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.1159.pdf
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