Abstract: Silica aerogels were synthesized from hybrid silicon sources of TEOS and acid silica sol by
two-step sol-gel method and supercritical drying. Different chemical compositions of the starting solution
were altered in order to make an insight into the relationship between process parameters and the
microstructural characteristics of resulting silica aerogels. The results indicate that a certain amount of
acid silica sol may promote the gelation process while excessive nano-scaled silica particles easily result
in dense structure and low specific surface area. The gelation time increases with the increasing water
amount. Excessive water will lead to weak network structure of silica gels and thus larger shrinkage and
lower porosity of the resulting silica aerogels.
Abstract: TiB2-Cu-Ni cermet composite was fabricated by self-propagating high-temperature synthesis
combined with Pseudo Hot Isostatic Pressing. The microstructure of the composite is fine and uniform.
The thermal shock resistance and ablation behavior of the TiB2-Cu-Ni composite was investigated by
heating it for twenty seconds using a plasma torch arc heater. Fatal breakup took place in the monolithic
TiB2 ceramic once the plasma arc flow faced the surface of the ceramic. Only a small crack was found on
the ablation surface of the TiB2-Cu-Ni composite. The thermal stress fracture resistance parameter, R,
and the critical energy release rate GIC of TiB2-Cu-Ni composite are at the same order with that of the
W/Cu alloy. It showed that the properties of thermal shock resistance and the ablation of the composite
are good. The fraction of mass loss of the homogeneous composite was 2.32 %, which was similar to that
of traditional W/Cu alloy. The volatilization of the metal binder and mechanical erosion was the main
mechanisms of the ablation.
Abstract: A novel approach was developed to prepare Ni-coated TiB2 cermet. Fine Ni particles with
mean particle size of about 80 nm were impacted onto coarse TiB2 particles having a mean size of about 5
μm to form Ni-coated TiB2 powder by Hybridization. The conventional blended TiB2-Ni powder, as well
as Ni-coated TiB2 powder, was sintered by hot pressing (HP) method and Spark Plasma Sintering (SPS)
method. Compared with the conventional blended TiB2-Ni cermet, particle features and mechanical
properties of the Ni-coated TiB2 cermet were investigated. The microstructure analysis reveals that the
thickness of Ni film is around 4 nm. It is concluded that the mechanical properties of Ni-coated TiB2
cermet are superior to the blended TiB2-Ni cermet.
Abstract: In order to decrease the heat-treatment time and avoid particle growth during the post-sintering
heat-treatment, the interaction of nitrogen with (Ti,W)(C,N)/(Ni,Mo) cermets was investigated at high
pressure. Sintered (Ti,W)(C,N)/(Ni,Mo) cermets with different starting formulations were heated at 1000
°C using nitrogen pressures up to 110 MPa. At this temperature and nitrogen pressure the nitriding time
for the formation of interaction zones more than 20 μm thick is decreased to 3 hours and no particle
growth occurs. The heat-treatment leads to a dramatic improvement in surface hardness and a very small
decline in transverse rupture strength of the (Ti,W)(C,N)/(Ni,Mo) cermets. The microhardness in the
near-surface area shows a transition of the highest microhardness to a lower as the interior is approached.
Abstract: In this paper, the Ti(CN)-based cermets were fabricated with ultrafine Ti(CN) powders,
additives WC, Cr2C3 and Mo, metal binder Ni by vacuum sintering and HIP treatment. The composition
of the mixture was Ti(CN)-10Mo-20WC-xCr2C3-20Ni. Effect of Cr2C3 addition on microstructure and
mechanical properties was investigated. Results indicated that with increasing Cr2C3 content, the relative
densities after vacuum sintering decreased and the grain sizes of cermets increased. Cr2C3 addition to the
cermets improved the hardness but had some negative effect on the performance of bending strength.
Abstract: Ni base alloy ceramic composite coating fabricated through vacuum fusion sintering process
can acquire high strength and good thermal fatigue resistance. Composite coating was mainly composed
of Ni base alloy and ellipsoidal ceramic particles with random orientation. The three-phases model is used
to study the thermal expansion strains in composite coating. First, Eshebly-Mori-Tanaka method was
used to determine effective eigen strain of two-phases model formed by the ellipsoidal matrix shell being
around a ellipsoidal ceramic particle, then disturbance strain in two-phases model aroused thermal
inconsistency is obtained. Finally thinking average stress in effective matrix vanish, the residual stress
field in Ni base alloy and particles can be gotten by considering random orientation of two-phases models.
It will exert influence on strength and fatigue life of the composite coating.
Abstract: By means of a finite element method model, the effects of property parameters of refractory on
thermal stress of injection lance have been studied. The results show that the maximum thermal stress
increases with the improvement of thermal conductivity and elastic modulus of refractory, while it
decreases at first and then increases with the improvement of the coefficient of expansion of refractory.
Abstract: The spherical nano-sized bioactive particles in the system of CaO-P2O5-SiO2 were bio-mimetically
synthesized using micro-emulsion method. The microstructures and properties of the bio- mimetic
nano-materials were characterized using XRD, FTIR, SEM/EDAX and TEM techniques. It was indicated
that the nano-particles possessed glassy structural characteristics. The porous composite for bone tissue
reconstruction was prepared by compounding poly (hydroxybutyrate-2-co-2-hydroxyvalerate) (PHBV)
and the nano-particles of bio-mimetic bioactive glasses (BMBG). Bone-like hydroxyl- carbonate-apatite
(HCA) could formed on the surface of porous composite by immersing the composite in simulated body
fluid (SBF) at 37°C for 8 hours. With increase of immersion time, the morphology of HCA changed from
spherical into flake-like crystals. The study on cells attachment of the porous PHBV/BMBG composite
proved that the material possessed satisfactory bioactivity, bio-mineralization function and cells
Abstract: The objective of this study was to investigate the inhibitory effect of the synthetic nanohydroxyapatite
(HA) on dental caries. The nano-HA was synthesized by using the depositing reaction of
Ca (H2PO4)2. The artificial dental caries was made by using sour solution and inoculating Streptococcus
mutans (S.mutans) to the Sprague-Dawley (SD) rat’s mouth respectively. After mineralization of solution
of nano-HA for 10 days, the hardness of enamel was measured. The inhibitory effect of the synthetic
nano-HA on dental caries was detected by gargling way to rinse the rat tooth with the solution of nano-HA
in the animal test. Transmission electron microscopy (TEM) revealed that the dried HA particles were
needle-like with ф5-20nm×60nm and the sintered HA particles were spherical with less than 100nm. The
remineralized test indicated that the solution of nano-HA with different shapes enhanced the hardness of
artificial caries and improved the remineralization of artificial caries. The animal test showed that the
dried nano-HA had the inhibitory effect on dental caries. The good absorptive effect of the nano-HA on
both the saliva protein and the glucans leads to the development of interventions that could reduce or
modify bacterial colonization of tooth surfaces.
Abstract: Dense HA/TCP bioceramics were immersed in pure bovine serum, rabbit serum and dog serum
to observe apatite formation. Deposited crystals were examined using SEM. Results showed that some
needle-like crystals formed on surface of sterilized HA/TCP, and needle crystals developed into sheet
crystals and stick crystals after ceramics were immersed in bovine serum and rabbit serum respectively.
The growth of crystals was maybe affected by the content of calcium, various kinds of albumen and
alkaline phosphatase in different serums and the different pH of serum.