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  • 1
    Electronic Resource
    Electronic Resource
    Oxidation kinetics of nickel nanoparticles (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3012-3017 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The oxidation kinetics of nickel particles with an approximate median size of 15 nm was determined by thermogravimetry. The particles had a thin initial oxide shell amounting to 36 wt % of the sample. The kinetics was studied in pure oxygen in the temperature range 135–235 °C, giving power law behavior of each isotherm with an exponent between 0.48 and 0.58. By use of a master plot technique an apparent activation energy of 1.34 eV was determined. The power law exponent is considerably lower than the one expected for diffusion limited oxidation of a spherical particle with an initial oxide shell. The deviations from parabolic kinetics are discussed in terms of nonlinear diffusion, grain growth, and particle agglomeration. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1325002
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation and characterization of new transition-metal complexes of dipyridylmethane dicarboxylic acids. Crystal structure of the copper(II) complex of 1,1-bis(6-carboxy-2-pyridyl)-1-methoxypropane (1988)
    s.l. : American Chemical Society
    Inorganic chemistry 27 (1988), S. 235-240 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00275a005
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation and Properties of Lead Zirconate Stannate Titanate Sintered by Spark Plasma Sintering (2004)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 87 (2004), 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: Lanthanum-doped lead zirconate stannate titanate ceramics were successfully compacted to full density by spark plasma sintering (SPS). SPS samples densified at 900° or 950°C exhibit nearly full density and fine grain size (about 300 nm). Compared with samples from conventional sintering (CS), SPS samples show larger permittivity accompanied by a deterioration in dielectric loss and special strain hysteresis loops similar to those of ferroelectric relaxors, with a diffuse AFE–FE phase transition and less field-induced longitudinal strain. The differences in the properties of SPS and CS materials are attributed to the variations of the resultant microstructures, especially the grain size, of the ceramics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2004.00606.x
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation of Titanium Nitride/Alumina Laminate Composites (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), 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: A preparation route for TiN/Al2O3 laminate composites has been described. A water-based process using Al2O3 and TiN slurries with solids contents of 40 and 35 vol%, respectively, was used to make TiN and Al2O3 tapes. The removal of the binder was monitored by weight-loss measurements in a thermogravimetry unit. Bodies composed of Al2O3 and TiN tapes were densified at temperatures of 1400° and 1500°C using the Spark Plasma Sintering® (SPS) technique. Densities of 〉98% of the theoretical densities were approached. Crack-free and almost fully densified TiN/Al2O3 compacts were prepared by heating the burned-out green bodies to the final sintering temperature (1500°C) at a rate of 100°C/min, and with a holding time of 5–10 min, under a pressure of 75 MPa. The microstructures of the obtained compacts were studied using scanning electron microscopy. Grain sizes in the sintered Al2O3 and TiN compacts were similar to those of the precursor powders. Hardness and indentation fracture toughness were measured at room temperature, and the monolithic compacts as well as the laminate composites exhibited anisotropic mechanical behavior; i.e., the cracks propagated much more easily in a direction parallel to the laminas than perpendicular to them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00234.x
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  • 5
    Electronic Resource
    Electronic Resource
    Self-Reinforced α-SiAlON Ceramics with Improved Damage Tolerance Developed by a New Processing Strategy (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), 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: Alpha-SiAlON ceramics with a refined self-reinforced microstructure, i.e., containing acicular grains with dimensions much smaller than those obtained in previous studies, embedded in a matrix consisting of submicrometer-sized isotropic grains, were prepared by applying a rapid one-step sintering procedure. To suppress the overabundant formation of α-SiAlON nuclei, a combination of stabilizing cations, Y + Yb, was used; to encourage formation of acicular α-SiAlON grains, a small amount of an extra liquid (∼3 vol%) was introduced; to avoid abnormal grain coarsening resulting from dynamic ripening, the final sintering temperature was set to just slightly above the minimum temperature threshold for activating grain growth (1700°C). The fully dense compacts obtained exhibited excellent thermal-shock resistance, and hardness and fracture toughness values of 20 GPa and 5.1 MPa·m1/2, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00550.x
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), 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: Ta0.33Ti0.33Nb0.33C and Ta0.33Ti0.33Nb0.33CxN1−x whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N2. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO2, Ta2O5, Nb2O5, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl2(g) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02028.x
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  • 7
    Electronic Resource
    Electronic Resource
    Decomposition Mechanisms in Aluminum Oxide–Apatite Systems (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), 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: Aluminum oxide was mixed with solid solutions of hydroxyapatite and fluorapatite, prepared by solid-state reactions, for a study of the relation between composites of apatite and of their phase stability in the presence of aluminum oxide. The amount of water released from the apatite was quantified from thermogravimetric measurements, and the fraction of vacancies present at the onset temperature of its decomposition in the presence of aluminum oxide was estimated. The results show that the decomposition takes place when a certain fraction of vacancies has been formed. By incorporation of F− in the structure, the fraction of vacancies was reduced and the thermal stability of apatite was improved. Based on these findings, a modified mechanism describing the thermal decomposition of hydroxyapatite in the aluminum oxide–hydroxyapatite system is formulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02176.x
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  • 8
    Electronic Resource
    Electronic Resource
    Electric Fatigue in Antiferroelectric Lead Zirconate Stannate Titanate Ceramics Prepared by Spark Plasma Sintering (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 fatigue behavior of lead zirconate stannate titanate (PZST) ceramics prepared by spark plasma sintering (SPS) was investigated. Polarization and strain hysteresis loops were monitored. The material shows a high resistance to fatigue because of bipolar electric cycling. Both maximum strain and switchable polarization first show a fatigue stage 0 to 105 cycles and then a fatigue-free period up to 108 cycles. The maximum losses of maximum strain and switchable polarization are 18% and 10% of their initial values, respectively. The dominant fatigue mechanism is assigned to the pinning of domain walls by charged defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00510.x
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  • 9
    Electronic Resource
    Electronic Resource
    Spark-Plasma-Sintering Consolidation of SiC-Whisker-Reinforced Mullite Composites (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), 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: Spark plasma sintering was applied to consolidate a series of SiC-whisker-reinforced mullite-matrix composites containing up to 30 vol% of whiskers. Bodies with relative densities higher than 99% were obtained at 1400°3C, using a holding time of 3 min and a uniaxial pressure of 50 MPa. The analysis of densification kinetics revealed that a shrinkage rate of about 10-3 s-1 was obtained even with a high whisker load, showing that the spark plasma sintering process is a rapid technique for fabricating whisker composites. The very rapid densification that occurs during spark plasma sintering allows little time for growth of the matrix grains. This, in turn, leads to improved mechanical properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2004.tb19942.x
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  • 10
    Electronic Resource
    Electronic Resource
    Stability and Oxidation Properties of RE-α-Sialon Ceramics (RE = Y, Nd, Sm, Yb) (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), 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: Oxidation studies of hot-pressed RE-α-sialons, REx-Si12-4.5xAl4.5xO1.5xN16-1.5x (with x= 0.40 for RE = Nd, Sm, Yb; and x= 0.48 for RE = Y) were carried out in oxygen in a TG apparatus for ca. 20 h. Very good oxidation resistance was found for the Yb-doped samples, with parabolic rate constants Kp similar/congruent 0.09 10-6-3 10-6 mg2cm-4s-1 in the temperature range 1250-1350°C. The promising performance of this material was corroborated by long-term oxidation experiments (5 days) in air at 1350°C. Although the oxidation kinetics can be described by simple equations related to the parabolic rate law (e.g., the arctan equation, ΔW/A0=α arctan bt+ct), the oxidation process in these materials is likely to be complex. The significantly lower oxidation resistance of the RE = Nd, Sm doped α-sialons, especially at higher temperatures, is related to the formation of melilite, RE2Si3−yAlyO3+yN4−y (y∼ 1), in these systems. The melilite phase is also responsible for the thermal instability of the Nd- and Sm-α-sialons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02504.x
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