Abstract: Transformation behaviors and shape memory characteristics of Ti-45Ni-5Cu alloy
ribbons fabricated by melt spinning were investigated by means of optical microscopy,
differential scanning calorimetries(DSC), X-ray diffraction and thermal cycling tests under
constant load. They depended largely on temperatures of liquid metal. The B2-B19-B19
two-step transformation occurred in the ribbons fabricated with the liquid whose temperature
was higher than 1723 K, while the B2-B19 one-step transformation occurred in the ribbons with
the liquid at 1673 K. The stabilization of the B19 martensite in Ti-45Ni-5Cu alloy ribbons was
ascribed to the high density of dislocations which made strong resistance to large lattice
deformation associated with a formation of the B19 martensite.
Abstract: Porous TiNi shape-memory alloy (TiNi SMA) bodies were produced from the (Ti+Ni)
powder mixture by self-propagating high-temperature synthesis (SHS) method. Various processing
variables such as ignition temperature and heating schedule were used to control the pore structure.
Relationship between pore structure and mechanical property was also investigated. An in vivo test
was performed to evaluate bone tissue response and biocompatibility of porous TiNi SMA. It
showed no apparent adverse reactions such as inflammation and foreign body reaction. Bone
ingrowth was found in the pore space of all implanted blocks.
Titanium-nickel intermetallic compound is well known as one
Abstract: Mechanically-alloyed NiAl powder was sintered by Spark-Plasma Sintering (SPS) process.
Densification behavior and mechanical property were determined. Above 97% relative density was
obtained after sintering at 1150oC for 5min. Crystallite size determined by the Scherrer method was
approximately 80 nm. TEM observation revealed a relative larger crystallite size. X-ray diffraction
analysis showed that the sintered bodies were composed mainly of NiAl phase together with Ni3Al
phase. Sintered NiAl body showed an average Vickers hardness of 555Hv, transverse-rupture
strength of 1393MPa, 4-point-bending strength of 1100MPa, and fracture toughness of 19.9MPa
Abstract: Nano-crystalline CeO2 was synthesized by the mechanical milling and subsequent
heat-treatment from the mixture of Ce(OH)4 as precursor, and NaCl as diluent. The diluent provided
diffusion barrier during milling and heat-treatment, which was easily dissolved out by deionized
water. The size of crystallite and the strain variance of CeO2 were depended on the temperature and
heat-treatment time: increased with the temperature (400~700oC) and time (1~24 hours) increasing,
and saturated near at 20nm in size owing to the densification of diluent. The synthesized
nano-crystalline CeO2 powder was applied as an abrasive in CMP (Chemical Mechanical
Planarization) slurry. When blanket-type SiO2 and Si3N4 wafers were polished with the slurries, the
removal rates (RR) of SiO2 and Si3N4 wafers and selectivities (RRSiO2/RRSi3N4) were influenced by
synthetic condition of abrasive, the suspension stability and the pHs of slurries.
Abstract: In order to control the grain size of Cu-15.0Zn-8.1Al shape memory alloy, the spark plasma
sintering (SPS) technique was applied. The sintering processes were carried out under different
atmospheres with a different powder size. The sintered bodies were denser under the Ar+4%H2 gas
atmosphere than under the 100% Ar gas. By using the small-sized powders, the fine microstructure
with average grain size of 2~3 was obtained. With the large-sized powders, the single martensitic
phase was observed with the average grain size of 70~72 . When the starting powders with different
sizes were mixed, it is confirmed that the average grain size of the manufactured alloys was 15 , but
the distribution of grain size was not uniform.
Abstract: Microstructural change of TiB2-Cu nanocomposite during spark plasma sintering (SPS)
was investigated. Under simultaneous action of pressure, temperature and pulse electric current
titanium diboride nanoparticles distributed in copper matrix move, agglomerate and form a
interpenetrating phase composite with a fine-grained skeleton. Increase of SPS temperatures and
holding times promotes the densification of sintered compacts due to local melting of copper
Abstract: [SiO2]x[TiO2]1-x(x = 0.1, 0.2, 0.3, 0.4) powders were prepared by hydrothermal reaction of titanium
isopropoxide (TIP) and tetraethyl-orthosilicate (TEOS) stabilized in acidic ethanol/water solution.
The size and phase of TiO2 particles were controlled by adjusting the SiO2 content and the
composition of the solvent system. The microstructure and photocatalytic activity of the prepared
SiO2-TiO2 nanoparticles were characterized by XRD, TEM, BET, Raman and UV visible
spectroscopic techniques. The major phase for all the prepared samples was anatase.
The particle size of 0.3SiO2-0.7TiO2 powders prepared with excess amount of ethanol (REtOH =
EtOH/alkoxide molar ratio = 120) was about 8.7 nm, while that of the sample prepared with small
amount of ethanol (REtOH = 4) was 9.9 nm. The photocatalytic activity of these composite powders
under excess ethanol was 1.5 times higher than that of pure TiO2 with respect to the decomposition
of 1,4-dichlorobenzene (DCB).
Abstract: Bioactive ORMOSILS (organically modified silicate), PDMS-CaO-SiO2-P2O5 with five different
P2O5 content (0, 0.01, 0.03, 0.06, 0.09 mol%) have successfully been synthesized by sol-gel process.
The hybrids have been prepared with polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS),
calcium nitrate tetrahydrate [Ca(NO3)2
4H2O] and triethyl phosphate (TEP) as starting materials
and subsequently soaked into the simulated body fluid (SBF) for different period of time and the
bioactivity of hybrids was determined by examining the apatite formation on the surface of the
specimen by FT-IR, Thin-Film X-ray Diffraction, and Scanning Electron Microscopy (SEM). All of
the prepared samples with different P2O5 content showed in vitro bioactivity. It was observed that
the increase in P2O5 content up to 0.03 mole % increases the apatite formation compared to P2O5-
free hybrids. However, further increase in P2O5 concentration slows down the formation of the
apatite layer most probably due to the decrease of pH of SBF by dissolution of a large amount of
Abstract: The sintered microstructure homogeneity of W-15wt%Cu nanocomposite powders
prepared from W-CuO mixture was investigated. The increment of heating rate considerably
affected the homogeneity of sintered microstructure. In case of the higher heating rate, the
microstructure was more homogeneous than that of the lower heating rate by reason of Cu-
exudation during heating-up process.
Abstract: Al2O3 compacts with various phases were prepared by hydrolysis and spark plasma
sintering (SPS) process of Al powder. The bayerite (-Al(OH)3) phase was derived by hydrolysis of
commercial Al powder with micron size, whereas the bohemite (AlO(OH)) phase was obtained by
hydrolysis of nano Al powder synthesized by pulsed wire evaporation (PWE) method. Compaction as
well as dehydration of both bayerite and bohemite was carried out simultaneously by SPS method,
which is used to fabricate nano powder into dense compacts with a rapid heating rate of about 100 °C
per min. under the pressure of 50 MPa. After compaction in the temperature ranges from 350 °C to
1100 °C, the bayerite and bohemite phases change into various alumina phases depending on the
compaction temperatures. The bayerite shows the phase transition of Al(OH)3 -Al2O3 -Al2O3
-Al2O3 sequences. On the other hand, the bohemite experiences the phase transition from
AlO(OH) to -Al2O3 at 350 °C showing AlO(OH) -Al2O3 -Al2O3 -Al2O3 -Al2O3