Güncel Gönderiler: Fen Bilimleri Enstitüsü
Toplam kayıt 2521, listelenen: 101-120
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The design of compositions for multi-cation doped ?-ß SiAlON ceramics by the Rietveld method
(2003)Although densification of ?-ß-SiAlON ceramics is easier by using sintering additives, it is difficult to achieve the designed composition and therefore the mechanical properties after sintering. This is mainly due to the ... -
Chemical durability behaviour of bulk glasses in the SrO-Mn2O3Fe2O3-MgO-ZrO 2-SiO2 (SMFMZS) system
(2001)It is known that the SrO-MgO-ZrO2-SiO2 (SMZS) system glasses with 40 weight % silica content seem to give a very high chemical endurance against highly alkaline solutions and can be recommended for the reinforcement of ... -
Transmission electron microscopy of SrO containing multi-cation doped ?-SiAlON ceramics
(2002)An advantage of ?-SiAlON is that it can accommodate cations of sintering additives and hence reduces the amount of deleterious remnant intergranular amorphous phase. However, it is believed that relatively large cations ... -
Effect of starting Si3N4 powder type and sintering conditions on the grain morphology of ?-SiAlON ceramics
(2002)Nitrogen rich neodymium-ytterbium containing multi-cation ?-sialon starting compositions have been prepared by gas pressure sintering using "conventional" ?-Si3N4 or plasma produced ß-Si3N4 powder. The effect of ?-SiAlON ... -
a-SiAION ceramics densified with mixed oxide sintering additives
(2000)Densification and stabilization of ?-sialon ceramics were investigated by using oxides of large cations (Sr2+, La3+, Ce3+, Nd3+) and their equi-molar mixtures with CaO or Yb2O3. All multi-cation and single cation (only ... -
Improvement of elongated ?-SiAlON ceramics by variation of the processing conditions and amounts of additives
(2001)Two types of Y-?-SiAlON composition, with different amounts of additional liquid phase were densified in a gas pressure sintering furnace using three different sintering cycles. One series of samples was heated up to 1825°C ... -
Novel developments in a-SiAION ceramics
(2000)Densification and stabilization of ct-sialon ceramics have been investigated by using oxides of large cations (Sr2+, La3+, Ce3+, Nd3+) and their equimolar mixtures with calcium or ytterbium as a principal cation. All ... -
Performance of new ?-ß SiAlONs in turning operations
(2001)New ?-ß SiAlON ceramics were produced, characterised and tested in turning operations of cast iron. Cutting speeds varied between 400-1200 m/min while feeding rates were between 0.3 to 0.5 mm/rev. The results were compared ... -
Hard and tough ?-SiAION ceramics
(2000)Yb, Nd/Ca and Ce/Ca containing a-sialon starting compositions have been densified by either pressureless sintering or capsul free sinter/HIP'ing using "conventional" ?-Si3N4 powder. X-ray diffraction studies of both ... -
Effects of different Si3N4 starting powders and sintering conditions on the grain morphology and mechanical properties of ?-SiAlON ceramics
(2001)The preparation of ?-SiAlON microstructures by ß-Si3N4 starting powder or by applying nucleation step during sintering was studied. The application of sintering cycles on nucleation effect and the effect of different Si3N4 ... -
Formation mechanisms and morphological changes during the hydrothermal synthesis of BaTiO3 particles from a chemically modified, amorphous titanium (hydrous) oxide precursor
(Elsevier Sci LTD, 2003)The formation mechanism of BaTiO3 under hydrothermal conditions was investigated. A coprecipitated precursor prepared from chemically modified titanium isopropoxide with acetylacetone and barium acetate was used as a ... -
The effect of different nucleation temperatures on the grain morphology of ?-SiAlON ceramics
(2003)Nitrogen rich yttrium-cerium containing multi-cation ?-SiAlON starting compositions were prepared by gas pressure sintering using conventional ?-Si3N4 powder. Microstructural characterization of the two stage sintered ... -
alpha ->beta sialon transformation in calcium-containing alpha-SiAlON ceramics
(Elsevier Sci LTD, 1999)Recent studies on rare earth densified a-sialon ceramics have shown that the resulting alpha-sialon product, present either as a single phase or in conjunction with beta-sialon, is unstable when heat treated at lower ... -
New heat treatment methods for glass removal from silicon nitride and sialon ceramics
(Kluwer Academic Publ, 2000)Sialon ceramics were discovered simultaneously (but independently) in late 1971 at Newcastle University and also at the Toyota Research Laboratories in Japan. During the 30 years since their original discovery, the Newcastle ... -
Preparation of Ce and Nd beta-sialon ceramics by alpha ->beta sialon transformation
(Inst Materials, 1997)It has previously been accepted that lanthanum and cerium do not form alpha-sialon structures because their ions are too large to enter the interstices in the structure. Recent work on heat treatment of rare earth densified ... -
Boron nitride-silicon carbide interphase boundaries in silicon nitride-silicon carbide particulate composites
(Elsevier Sci LTD, 2002)Interphase boundaries between SiC and h-BN grains in hot isostatically pressed Si3N4-SiC particulate composites made from both as-received powders and deoxidised powders, in which sub-micron size h-BN particles occur as a ... -
The dependence of equilibrium film thickness on grain orientation at interphase boundaries in ceramic-ceramic composites
(Elsevier Science BV, 2000)High-resolution transmission electron microscope observations of hexagonal boron nitride - 3C silicon carbide interphase boundaries suggest that where one or more phases is highly anisotropic, an orientation dependence on ... -
Transmission electron microscopy of interfaces in structural ceramic composites
(Blackwell Science LTD, 1999)Ceramic composites based either on a particulate, fibre or a lamellar architecture are potentially useful as damage-tolerant high-temperature engineering materials. The ability of the interfaces in such systems to deflect ... -
High resolution transmission electron microscopy of grain boundaries between hexagonal boron nitride grains in Si3N4-SiC particulate composites
(Wiley-V C H Verlag GMBH, 2000)High resolution transmission electron microscope observations of grain boundaries in hexagonal boron nitride in which adjacent grains are rotated with respect to one another about either <2 (1) over bar (1) over bar 0> or ...
