Abstract: AlN-SiC ceramics with 0 to 75 mol% of AlN were fabricated through pressureless
sintering of very fine AlN and SiC. Powder compacts with different amounts of AlN were fired at
2000°C for 1 h in Argon gas flow using an induction-heating furnace. The microstructure and
phases present in the products were evaluated using SEM and XRD. The AlN-SiC ceramics had a
porous structure with 30% porosity, and the grain size was increased with the addition of AlN. XRD
analysis showed that 2H was a main phase in all samples, though 3C and 6H phases were found in
25 mol%AlN-75 mol%SiC ceramic. The electrical properties of the AlN-SiC ceramics were
evaluated at various temperatures ranging from room temperature to 300°C. The electrical
conductivity of the AlN-SiC ceramics depended on the amount of AlN and on the temperature. The
75 mol%AlN-SiC ceramic had higher electrical resistance, though the other samples were electrical
conductors. The highest electrical conductivity was obtained with the 25 mol% AlN composition,
which was 7 S/m at room temperature and 30 S/m at 300°C. The Seebeck coefficient for the
AlN-SiC ceramics increased with rising temperatures. The AlN-SiC ceramics with 50 mol%AlN
had the highest Seebeck coefficient of 220 2V/K at 300°C.
Abstract: Si3N4 ceramics with V2O5 based glasses as sintering additives were successfully
fabricated by a powder mixing process and rapid sintering by the PECS method. The fabricated
materials by Pulsed Electric Current Sintering (PECS) exhibited very fine microstructure with α
and β grains. Electric conductivity for the Si3N4/(V2O5-B2O3) and the Si3N4/(V2O5-B2O3-Al2O3) at
room temperature were four and six orders of magnitude higher at room temperature, and two and
three orders of magnitude higher at 1000 oC than the conventional Si3N4, respectively
Abstract: The Si3N4/YSiO2N composite in which crystalline YSiO2N was formed as grain boundary
phase was fabricated by hot-pressing the mixture of SiO2, Si3N4 and Y2O3. The fracture toughness of
this composite was significantly improved, compared to the Si3N4 composites containing Y5Si3O12N
or Y2Si3O3N4 as a grain boundary phases. To clarify the toughening mechanism, the microstructure
and the crack propagation profiles were observed.
Abstract: Electrically conductive AlN ceramics were fabricated by the addition of a small amount of
B4C and sintering aid, and hot-press sintering in a nitrogen atmosphere. The electrical resistivity of
AlN ceramics decreased remarkably from 1014 cm to the range of 100 to 102 cm by a minimum of
2.3 wt% of B4C addition. This resistivity decrease was caused by forming three-dimensional networks
composed of boron carbonitride (B-C-N) platelets synthesized during sintering. To produce the
networks of B-C-N platelets, two-step sintering with a heat-treatment step at 1600°C before the
densification step at 2000°C was needed.
Abstract: In this study, we propose a new process to fabricate electrically conductive alumina by
gelcasting and reduction sintering. The process used the conventional gelcasting method except for
varying amounts of monomer at 2.8, 5.5, and 8.0 wt.% relative to the weight of the slurry. In the plastic
mould, the slurry was under in situ solidification for 3 hrs at 25oC to achieve gelation. The freshly gelled
bodies were demolded, carefully dried, and then sintered at 1100oC, 1300oC, and 1550oC in nitrogen
atmosphere. The holding times at 1100oC and 1300oC was 2 hours, while at 1550oC were 2, 4, and 6 hrs.
The sintered alumina body was characterized by electrical property, X-ray diffraction, and scanning
electron microscopy. Results showed that monomer additions and sintering schedule significantly affect
in lowering electrical resistance. The low value was 3.6×106 +cm at 8.0wt.% monomer addition and
sintering at 1550oC for 2 hrs. The effect of physical properties on electrical conductivity and the
corresponding reaction mechanism were discussed in details.
Abstract: Multi Wall Carbon Nanotubes (MWCNTs) with a diameter of 20-30 nm were used as a
conductive phase to add electric conductivity to yttria stabilized tetragonal zirconia (3Y-TZP).
Almost fully dense 3Y-TZP/MWCNTs nanocomposite was obtained by pressureless sintering under
inert atmosphere and Hot Isostatic Pressing (HIP) treatment. The conductivity of the
nanocomposites increased with increasing content of MWCNTs. Moreover, the fracture toughness
increment of the composite was confirmed at 0.5 wt% addition. Scanning electron microscopy and
transmission electron microscopy observation of the microstructures showed that MWCNTs were
fairly homogeneously dispersed in the 3Y-TZP matrix.
Abstract: CNTs/Fe/Al2O3 nanocomposites were prepared by thermal CVD and SPS methods. The
dispersion of CNTs in the Fe/Al2O3 matrix were controlled by an attrition milling process. FESEM
analysis revealed that the CNTs of 5 vol.% were homogeneously dispersed in the Fe/Al2O3. The
effects of CNTs dispersion on the mechanical and electrical properties of the specimens were
investigated. Fracture strength and electrical conductivity of 5 vol.% CNTs/Fe/Al2O3 specimen
were measured at 641 MPa and 2.93 10-11 mS/m, whereas that of a 20 vol.% CNTs/Fe/Al2O3
specimen were 208 MPa and 8.46 10-7 mS/m, respectively. In comparison with an Al2O3
monolith, the specimen with 5 vol.% CNTs showed enhanced fracture strength and increased
Abstract: Polymer/layered silicate nanocomposities were prepared by in situ polymerization with
microwave process. The influence of the amount of clay on the structure and thermal properties for
the synthesized nanocomposites were characterized by means of X-ray diffraction (XRD),
transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal
gravimetric analysis (TGA). It was found that the structure of nanocomposites, an
intercalated/exfoliated structure, depended on the clay content.
Abstract: 3Y-TZP/TiNiCo composites have been successfully fabricated by three step heating
(dehydrogenation, hydrogen reduction, hot-pressing) of 3Y-TZP /NiO/TiH2/CoO powder mixtures.
XRD analysis revealed that TiNi-base intermetallic compounds such as Ni4Ti3, NiTi, Ni3Ti had
formed. The bending strength of 3Y-TZP/TiNiCo composites (~650 MPa) were much higher than
those of 3Y-TZP monolith (350 MPa) sintered at the same condition. The electrical resistivity
characteristics indicated that 3Y-TZP/30 vol%TiNiCo composites were good electrical conductors.
Cobalt addition to TiNi phase influenced on electrical properties of final composites, while their
fracture strength was unchanged by the Co addition.
Abstract: Preparation of monodispersed inorganic-organic hybrid particles has become one of the
most attractive research topics in recent years. In this study, phenylsilsesquioxane (PhSiO3/2) particles
were synthesized from phenyltriethoxysilane (PhSi(OEt)3), ethanol (EtOH), hydrochloric acid for
hydrolysis and ammonia water for polycondensation by the sol-gel method. Spherical PhSiO3/2
particles were obtainable by varying the mole ratios of EtOH, H2O, HCl and NH3, to PhSi(OEt)3. The
particle size was changed from 0.1 to 5.0 .m with the mole ratio. Under the optimum conditions,
monodispersed particles with 1.50 .m in diameter and 0.05 of normalized standard deviation were