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  • 1
    Electronic Resource
    Electronic Resource
    Electrical relaxation in a glass-forming molten salt (1974)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 78 (1974), S. 639-648 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100599a016
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  • 2
    Electronic Resource
    Electronic Resource
    Densification and microstructure development during the sintering of submicrometre magnesium oxide particles prepared by a vapour-phase oxidation process (1993)
    Springer
    Journal of materials science 28 (1993), S. 719-728 
    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 densification behaviour and microstructure development of MgO compacts fired from room temperature up to 1700°C at a heating rate of 10°C min−1 were examined. Starting materials were seven kinds of MgO powder with primary particle sizes ranging from 11–261 nm; these powders were produced by a vapour-phase oxidation process. The original powders contained agglomerates, due to the spontaneous coagulation of primary particles, which ranged in size from 100–500 nm. The MgO compacts densified during firing by three types of sintering: sintering within agglomerates; sintering between agglomerates and grains; and rearrangement of agglomerates and grains. The MgO compact with the lowest primary particle size (11 nm) densified by the first and second types of sintering, but the effects of these two types of sintering decreased when the primary particle size became 44 nm; here the rearrangement of agglomerates and grains primarily contributed to densification of the compact. All three types of densification became less complete with further increases in primary particle size up to 261 nm. The relative densities of the MgO compacts with smaller primary particle sizes (11–44 nm) became 96–98% when the compacts were fired up to 1700°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01151248
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  • 3
    Electronic Resource
    Electronic Resource
    Some properties of aluminium nitride powder synthesized by low-pressure chemical vapour deposition (1993)
    Springer
    Journal of materials science 28 (1993), S. 1631-1638 
    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 Aluminium nitride (AIN) powders were synthesized by a low-pressure chemical vapour deposition, i.e. reactions of vaporized aluminium with various compositions of NH3-N2 gases at 1050°C under a pressure of 0.1–1.3 kPa. The properties of the resulting powders were divided into three categories, according to the NH3 content in the NH3-N2 gases: (i) 0 ⩽ NH3 〈 40%, (ii) 40⩽NH3⩽60%, and (iii) 60〈NH3⩽100%. In Region (i), the unreacted aluminium adhered to the AIN crystallites to form spherical primary particles; in Region (ii), the spherical agglomerates with diameters of 0.2–0.5 μm, composed of primary particles, were present as minimum units of secondary particles; in Region (iii), the crystal growth of AIN was enhanced with increasing NH3 contents. The primary particles formed by the reaction of aluminium vapour with NH3-N2 gases containing NH3⩾40% were single crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363359
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  • 4
    Electronic Resource
    Electronic Resource
    Formation of porous calcium phosphate films on partially stabilized zirconia substrates by the spray-pyrolysis technique (1995)
    Springer
    Journal of materials science 30 (1995), S. 4936-4945 
    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 Porous calcium phosphate films could be formed on partially stabilized zirconia (3YZ) substrates by a spray-pyrolysis technique. The use of calcium metaphosphate as a binder was effective to enhance the binding strengths of these films to the substrates. The crystalline phase in the resulting films was mainly β-calcium orthophosphate. This phase was thermally stabilized by solid solution with Y3+. The thickness of the film (30–150 μm) was dependent upon the spraying time; the pore size was about 15 μm. The films were still present on the substrate after Scotch tape (810) was adhered to the film side and then taken off from the substrate. The films prepared in this study were found to bind strongly to the substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01154507
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  • 5
    Electronic Resource
    Electronic Resource
    Some properties of mullite powders prepared by chemical vapour deposition (1995)
    Springer
    Journal of materials science 30 (1995), S. 1158-1165 
    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 chemical vapour deposition (CVD) technique based upon reaction among aluminium chloride (AlCl3), silicon chloride (SiCl4) and oxygen was applied to produce submicrometresized mullite (3Al2O3 ·2SiO2) powder. The conditions for preparing the best crystalline mullite were as follows: (i) the reaction temperature, 1200 °C; (ii) the flow rate of carrier gas (Ar) of AlCl3, 0.3 dm3 min−1, and that of SiCl4, 0.3 dm3 min−1; (iii) the sublimation temperature of AlCl3, 180 °C, and the evaporation temperature of SiCl4, 25 °C; and (iv) the flow rate of oxygen, 0.9 dm3 min−1. The as-prepared powder contained mullite, a small amount of γ-Al2O3 (Al-Si spinel) and amorphous material; this powder was composed of spherical primary particles of ∼ 0.05 μm diameter. Although only mullite was present at the calcination temperature of 1300 °C, a small amount of α-Al2O3 was formed at 1400–1700 °C. Agglomeration due to primary particle growth started at temperatures exceeding 1400 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00356114
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  • 6
    Electronic Resource
    Electronic Resource
    Sintering of magnesium oxide powder prepared by vapour-phase oxidation process — Relationship between particle size and mechanical properties of consolidated specimens (1996)
    Springer
    Journal of materials science 31 (1996), S. 2757-2765 
    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 Relationship between powder properties and bending strengths of the sintered magnesium oxide (MgO) specimens was examined using seven kinds of MgO powders prepared by a vapour-phase oxidation process; the average primary particle sizes were 11, 25, 32, 44, 57, 107 and 261 nm. These compressed powders (specimens) were fired at 1600 or 1700 °C for 1 to 15 h. Although the densification behaviours of the specimens varied with the primary particle size of the starting powders, the relative densities of the specimens fired at 1700 °C for 5 h were all in the range of 97–98%. The relationships between bending strengths and grain sizes of these sintered specimens could be classified into two categories, according to the primary particle size of the starting powder: (i) at and below 32 nm and (ii) 44–261 nm. In range (i), the bending strengths of the sintered specimens were as low as ∼ 120 MPa; the grain size was reduced from 50.7 to 35.8 μm as the primary particle size decreased from 32 to 11 nm. In range (ii), as the primary particle size increased from 44 to 261 nm, the bending strength of the sintered specimen was enhanced from 162 to 183 MPa, while the grain size was reduced from 28.3 to 13.7 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687312
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of hydroxyapatite powders prepared by ultrasonic spray-pyrolysis technique (1999)
    Springer
    Journal of materials science 34 (1999), S. 2865-2873 
    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 hydroxyapatite (HAp) powder was prepared by the ultrasonic spray-pyrolysis technique; the characterization of the resulting powders was performed. Five kinds of the starting solutions with the Ca/P ratio of 1.67 were prepared by mixing Ca(NO3)2, (NH4)2HPO4 and HNO3; the concentrations of Ca2+ and PO4 3− were in the ranges of 0.10 to 0.90 mol · dm−3 and 0.06 to 0.54 mol · dm−3, respectively. These solutions were sprayed into the heating zone to prepare the HAp powders. The heating zone was composed of two electric furnaces; the lower furnace was used for the evaporation of the solvent from the droplets (300–500°C) and the upper furnace for the pyrolysis of the precipitated metal salts (750–900°C). The easily sinterable HAp powder was prepared by spray-pyrolysing the solution with Ca2+ (0.50 mol · dm−3) and PO4 3− (0.30 mol · dm−3) at the temperatures of 800°C (the upper furnaces) and 400°C (the lower furnaces). The resulting powder was composed of the spherical particles with diameters of ∼1 μm or below. Even without the calcination and grinding operations, the relative densities of the compacts fired at 1150 and 1200°C for 5 h attained maxima ∼95%. The microstructure of the sintered compacts appeared to be uniform; the average grain size was ∼3 μm. The activation energies for the grain growth of the sintered HAp compacts were 120 to 147 kJ · mol−1 · K−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004635418655
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  • 8
    Electronic Resource
    Electronic Resource
    Agglomeration of magnesium oxide particles formed by the decomposition of magnesium hydroxide (1989)
    Springer
    Journal of materials science 24 (1989), S. 2603-2609 
    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 agglomeration process of MgO powder derived from Mg (OH)2 was investigated at fixed temperatures of 600, 800, 900 and 1200° C; these temperatures were chosen as representative of four regions, i.e. below 600° C, 650 to 850° C, 850 to 1050°C and 1050 to 1200° C previously reported. At 600° C, coherent crystallites coalesced within the heating time of 60 min; on further heating till 300 min, the primary particles which consisted of crystallites grew rapidly. The original Mg (OH)2 framework or pseudomorphs, composed of minute crystallites and primary particles, still remained in the powder. At 800° C, the pseudomorphs had disintegrated into fragments. The crystallite growth and primary particle growth were accelerated with increasing the heating times beyond 60 min. At 900° C, a further fragmentation of agglomerates occurred with increasing the heating times; the crystallite and primary particle growth in fragments brought about the pore coalescence. At 1200° C, the crystallite and primary particle growth proceeded with the coarsening of pores; on heating beyond 240 min, the crystallites and primary particles grew rapidly due to the entrapment of pores within them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01174532
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