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  • 1
    Electronic Resource
    Electronic Resource
    Influence of Powder Agglomerates on the Structure and Rheological Behavior of Injection-Molded Zirconia–Wax Suspensions (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: Surface-modified zirconia powders with 20% to 100% of the particle surface area covered with stearic acid was blended with 50 vol% of an organic wax vehicle for rheological study. These fractions of surface coverage gave rise to different degrees of powder agglomeration. A further adsorption of the wax on partially modified particle surfaces was examined, which was likely to exhibit different degrees of solid surface-wax affinity depending upon whether the particle surfaces were “bare” or “premodified.” The rheological behavior of the suspensions revealed that the shear viscosity as well as the yield stress increased appreciably with decreased fractions (or surface coverage) of the pre-adsorption. The observed suspension rheology due to incomplete surface modification can be accounted for by the formation of agglomerates which suppress suspension flowability to a significant extent. The formation of the agglomerates alters the suspension structure by reduction of the maximum solid concentration (φmax) that is attainable for a given powder. This change in suspension structure (decrease in φmax) leads to a restriction of particle mobility, reflected as a linear function of the yield stress of the suspensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02136.x
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal diffusivity/conductivity in SiAlON ceramics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 494-496 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal diffusivity and conductivity of ceramic materials in a system of Si3N4-SiO2-Al2O3-AlN composed of α and β SiAlON (which is well known as duophase SiAlON ceramics) are investigated. Single-phase β-SiAlON ceramic has a thermal conductivity of 12.44 W/m K. The thermal conductivities of SiAlON ceramics decrease linearly with increasing content of α phase and can be best described by the following equation: K=12.46–0.043 f, where f is the weight percentage of α-SiAlON content and K is the thermal conductivity of SiAlON ceramics. The thermal conductivity of single-phase α-SiAlON was then estimated to be ∼8.16 W/m K, which is in excellent agreement with the literature reported values, ∼8.4 W/m K. This estimation is also close to the value, 8.22 W/m K, obtained by using Bruggeman's variable dispersion theory. The temperature dependence of the thermal conductivity of duophase SiAlON ceramics varies with α and β phase contents in the materials. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359030
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal conduction behavior in polycrystalline (Sr1−x,K2x)Zr4(PO4)6 ceramic (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3765-3768 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-phase (Sr1−x,K2x)Zr4(PO4)6 ceramic (with x=0.0–0.8) demonstrated values of thermal conductivity decrease with increasing potassium content to a minimum value at x=0.5, which suggests a maximum content of lattice defect, i.e., oxygen vacancy, at this composition. The thermal conductivity of the ceramic then increased with further increase of potassium. The thermal conduction in (Sr1−x,K2x)Zr4(PO4)6 ceramic (at x=0.5) appears to exhibit a strongly lattice-defect dependence with a calculated phonon mean free path of approximately 3.04 A(ring), rather than a phonon-phonon dependence as observed in a number of dielectric materials. A linear relationship of the thermal conductivity in terms of porosity with temperature up to 600 °C has been correlated and can be simply expressed as K=K0 (1−p) regardless of the influence of emissivity factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356050
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Dispersants on the Rheological Behavior of Zirconia-Wax Suspensions (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: Three types of fatty acids-namely, stearic acid, oleic acid, and 12-hydroxystearic acid-were used as dispersants for stabilization of highly concentrated zirconia-wax suspensions. Rheological properties such as viscosity and yield stress of the suspensions were determined over a temperature range of 65°-85°C. Experimental results indicated that better suspension stabilization was achieved when the 12-hydroxystearic acid was used. Adsorption behavior revealed a greater affinity at the solid/liquid interface that occurred for the 12-hydroxystearic acid than for stearic acid or oleic acid. This observation suggests that the adsorption of 12-hydroxystearic acid may lead to a better packing (or surface concentration) of the acid molecules onto the solid surface than others and also results in a better suspension fluidity and processability. Attractive interparticle interaction was estimated quantitatively by using the Vold model and resulting analysis showed a linear correlation between the yield stress and the attractive potential for the suspensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb01890.x
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  • 5
    Electronic Resource
    Electronic Resource
    Fabrication of hydroxyapatite ceramic with controlled porosity (1997)
    Springer
    Journal of materials science 8 (1997), S. 227-232 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Porous hydroxyapatite (HAp) ceramics were fabricated using poly vinyl butyral (PVB) as a porosifier. The effects of preparation conditions involving PVB particle size, sintering time, and forming pressure (die-pressing technique) on the resultant pore size/structure as well as the pore size distribution were investigated. The experimental results showed that the HAp ceramics with controlled pore characteristics such as pore volume fraction, pore size and pore structure are achievable. It provides the possibility to design HAp ceramics with diverse porosities simulating that of natural bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018591724140
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  • 6
    Electronic Resource
    Electronic Resource
    Formation of a new bioactive glass-ceramic (1994)
    Springer
    Journal of materials science 5 (1994), S. 7-10 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: A new bioactive glass-ceramic with a nominal composition of CaO (54.5), MgO (6.0), SiO2 (32.8), P2O5 (6.1) and CaF2 (0.6), by weight ratio, has been developed. The crystalline phases termed hydroxyfluoroxyapatite, akermanite, and wollastonite were found to be present simultaneously at a temperature of 930°C. Furthermore, no cracks appear after the bulk glass is crystallized. This newly developed glass-ceramic has an average flexural strength of 233 MPa and a fracture toughness of 2.95 MPa m1/2, which are higher values than for dense hydroxyapatite and known glass-ceramic. An apatite layer containing Ca, P and Si is formed on the surface after the glass-ceramic is soaked in a simulated body fluid for a short period of time, which is indicative of a high bioactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121146
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  • 7
    Electronic Resource
    Electronic Resource
    Sintering of (Ca1−x , Mg x )Zr4(PO4)6 ceramics (1994)
    Springer
    Journal of materials science 29 (1994), S. 1507-1513 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Densification and grain growth of (Ca1−x , Mg x )Zr4(PO4)6 (CMZP; where x=0.0, 0.1, and 0.4) ceramics at the intermediate stage of sintering have been investigated. A lattice-diffusion model proposed by Coble with tetrakaidecahedron as a grain shape was employed and appears to be applicable to the sintering of CMZP. The apparent diffusion coefficient of the CMZP ceramics for x=0.0 is lower by approximately three and one orders of magnitude than for x=0.1 and x=0.4, respectively. The grain growth in CMZP at the intermediate stage of sintering follows a third-power kinetics, i.e. n=3. A modified expression using the lattice-diffusion model associated with grain-growth kinetics has been derived which makes the microstructures of CMZP controllable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368917
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of solids loading on the green microstructure and sintering behaviour of ceramic injection mouldings (1997)
    Springer
    Journal of materials science 32 (1997), S. 6475-6481 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of solid loading of ceramic injection mouldings containing 45–60 vol% submicrometre zirconia powders on the green microstructure and sintering behaviour was investigated. The mouldings with lower solids content exhibit a coarser green microstructure, which, in turn, shows lower sintering activity. The sintering activity is largely improved by increasing the solids loading to 60% at which a sintered density of 99% theoretical can easily be attained at 1400°C, which is primarily because of the evolution of a finer green microstructure. The green microstructure of the mouldings, along with the sintering behaviour, was found to be well correlated with the average pore diameter, rather than the most-frequent pore diameter in the pore-size frequency distribution of the green compacts. The moulded compacts, although containing considerable amount of agglomerates, show isotropic shrinkage behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018646824219
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of ceramic powders of different characteristics on particle packing structure and sintering behaviour (1999)
    Springer
    Journal of materials science 34 (1999), S. 1959-1972 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ytteria-stabilized zirconia powders from different sources were used to investigate powder packing characteristics and subsequent sintering behaviour. Powders of different levels of agglomeration were controlled by varying degrees of ball-milling, followed by shaping through colloidal casting. Experimental findings revealed that the average pore diameter of the powder compacts appears to be a good representative of the whole pore structure of the green compacts. This pore parameter exhibited a well-defined correlation with respect to the initial mean powder size for each type of powder, irrespective of the difference in particle size distribution and degree of agglomeration, and also correlated soundly with the sintering behaviour of the powder compacts. Critical pore diameter/particle size ratios were experimentally determined, which were shown to be strongly related to the initial particle size by a power-law dependence. This dependence offers an excellent prediction of the critical ratio in alumina powder compacts reported by Zheng and Reed [27], which further supports the feasibility of this relationship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004500418038
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  • 10
    Electronic Resource
    Electronic Resource
    Heat conduction in ionic polycrystalline “nanocomposites” (1994)
    Springer
    Journal of materials science 13 (1994), S. 1697-1698 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451744
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