• Composites Research
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• v.28 no.5
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• pp.270-276
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• 2015

Polyvinylidene fluoride (PVDF)-based nanocomposites are fabricated by incorporation of boron nitride (BN) nanosheets with anisotropic orientation for a potential high thermal conducting ferroelectric materials. The PVDF is dissolved in dimethylformamide (DMF) and homogeneously mixed with exfoliated BN nanosheets, which is then cast into a polyimide film under application of high magnetic fields (0.45~10 T), where the direction of the filler alignment was controlled. The BN nanosheets are exfoliated by a mixed way of solvothermal method and ultrasonication prior to incorporation into the PVDF-based polymer suspension. X-ray diffraction, scanning electron microscope and thermal diffusivity are measured for the characterization of the polymer nanocomposites. Analysis shows that BN nanosheets are exfoliated into the fewer layers, whose basal planes are oriented either perpendicular or parallel to the composite surfaces without necessitating the surface modification induced by high magnetic fields. Moreover, the nanocomposites show a dramatic thermal diffusivity enhancement of 1056% by BN nanosheets with perpendicular orientation in comparison with the pristine PVDF at 10 vol % of BN, which relies on the degree of filler orientation. The mechanism for the magnetic field-induced orientation of BN and enhancement of thermal property of PVDF-based composites by the BN assembly are elucidated.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.167-177
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• 2016

Smectitic clays, occurring in Kırka and Bigadiç boron evaporite deposits formed in Miocene playa lake environment in Turkey, contain $LiO_2$ 0.02-0.21% and 0.16-0.30%, respectively, and boron tailings are also reported to contain $LiO_2$ 0.04-0.26%. Lithium in smectitic clays was identified to be retained in hectorite. The XRD results revealed that hectorite was contained in 25.7% and 79.7% of Kırka and Bigadiç deposit samples respectively. In this study, we selected a clay sample from each deposit with lithium content of ~0.18% and estimated extractable lithium by acid treatment and roasting method commercially applicable to lithium resources, such as lepidolite and hectorite. When 1 g of crushed clay (particle size less than $74{\mu}m$) was reacted with 200 mL of 0.25 M HCl solution, the amount of lithium dissolved increased with the increase of reaction time up to 10 hours for both samples. Reaction time longer than 10 hours did not significantly increased the amount of lithium dissolved. After 10 hours of reaction, 89% of lithium in the clay sample from the Kırka deposit was dissolved, while 71% of lithium was dissolved from the Bigadiç deposit tailing sample. 87% of lithium in the clay sample from the Kırka deposit was extracted and 82% of lithium was extracted from the Bigadiç deposit tailing sample by the roasting extraction method, where clays were leached after a thermal treatment at $1,100^{\circ}C$ for 2 hours with $CaCO_3$ and $CaSO_4$.

• Journal of the Korean Ceramic Society
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• v.34 no.9
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• pp.941-948
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• 1997

CuCl nanocrystallites dispersed nonlinear optical silica and borosilicate glasses were fabricated by sol-gel process. CuCl powder was dissolved in TEOS(Si(OC2H5)4) and TMB((CH3O)3B), precursors of silica and borosilicate glasses, with ethanol, water and HCl, and precipitated through the heat treatment in the matrix glass. The optical properties of CuCl doped glasses were measured using the spectrophotometer at room temperature and low temperature(77K); Z1, 2 and Z3 exciton peaks from the absorption spectra, were observed at about 370 nm and 380 nm, respectively. The average radius of nanocrystallites, calculated from the blue shift of Z3 excitons, was measured according to annealing temperature and time. The precipitation temperature of CuCl nanocrystallites was decreased when boron was added to silica glass. Increase of annealing temperature and time made average radius of nanocrystallites saturated about 2 nm.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.220-224
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• 2002

The oxide scales formed on $Ni_3Al$-7.8%Cr-1.3%Zr-0.8%Mo-0.025%B after oxidation at 900, 1000 and 110$0^{\circ}C$ in air were studied using XRD, SEM, EPMA and TEM. The oxide scales consisted primarily of $NiO,\; NiAl_2O_4,\;{\alpha}-Al_2O_3,\; monoclinic-ZrO_2,\; and \;tetragonal-ZrO_2$. The outer layer of the oxide scale was rich in Ni-oxides, whereas the internal oxide stringers were rich in Al-oxides and $ZrO_2$. Within the above oxide scales, Cr and Mo tended to exist as dissolved ions.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.379-387
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• 1989

The synthesis of borosilicate consisted of boron and silicon was stadied. The composition, acidity and adsorption characteristics of synthesized borosilicate were examined. The synthesis rate increased with temperature and concentration of $Na_2O$, but the enhansing effects were different according to the reaction conditons. The synthesis process could be simulated by solution transfer mechanism assuming that crystals grow on the surface of crystal or nuclei with dissolved reactant. Adsorption characteristics of synthesized borosilicate was discussed with temperature programmed desorption patterns of ammonia and propylene and adsorption isotherms of propylene and propane.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.771-778
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• 2013

Gas hydrate (GH) process is a new desalination technology, where GH is a non- stoichiometric crystalline inclusion compounds formed by water and a number of gas molecules. Seawater GH is produced in a low temperature and a high pressure condition and they are separated from the concentrated seawater. The drawback of the GH process so far is that salt contents contained in its product does not meet the fresh water quality standard. This means that the GH process is not a standalone process for seawater desalination and it needs the help of other desalting process like reverse osmosis (RO). The objective of this study is to investigate the effect of GH process on energy saving for RO process in seawater desalination. The GH product water quality data, which were obtained from a literature, were used as input data for RO process simulation. The simulation results show that the energy saving effect by the GH process is in a range of 68 % to 81 %, which increases as the salt removal efficiency of the GH process increases. Boron (B) and total dissolved solids (TDS) concentrations of the final product of the hybrid process of GH and RO were also investigated through the RO process simulation to find relavant salt rejection efficiency of the GH process. In conclusion, the salt rejection efficiency of the GH process should exceed at least 78% in order to meet the product water quality standards and to increase the energy saving effect.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.335-340
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• 2005

The forward dissolution rate of a borosilicate waste glass was determined as an interlaboratory study(ILS) testing program for the evaluation of precision in the measurement of the dissolution rate or a waste glass using a single-pass flow-through(SPFT) test, whose conducting practice has been written for standardization through American Society for Testing and Materials (ASTM). A simulated low-activity waste glass powder with a size of 100/200 mesh was dissolved by lithium buffer solution (pH=10) at 70? under Ar atmosphere. By plotting the dissolution rates as a function of silicon and boron concentration in eluate, the forward dissolution rate of the glass was obtained as about $2.7\times10^{-5}g{\cdot}m{\cdot}s^{-1}$ in our laboratory.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.200-200
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• 2010

In recent times, metal oxide semiconductors thin films transistor (TFT), such as zinc and indium based oxide TFTs, have attracted considerable attention because of their several advantageous electrical and optical properties. There are many deposition methods for fabrication of ZnO-based materials such as chemical vapor deposition, RF/DC sputtering and pulsed laser deposition. However, these vacuum process require expensive equipment and result in high manufacturing costs. Also, the methods is difficult to fabricate various multicomponent oxide semiconductor. Recently, several groups report solution processed metal oxide TFTs for low cost and non vacuum process. In this study, we have newly developed solution-processed TFTs based on Ti-related multi-component transparent oxide, i. e., InTiO as the active layer. We propose new multicomponent oxide, Titanium indium oxide(TiInO), to fabricate the high performance TFT through the sol-gel method. We investigated the influence of relative compositions of Ti on the electrical properties. Indium nitrate hydrate [$In(NO^3).xH_2O$] and Titanium isobutoxide [$C_{16}H_{36}O_4Ti$] were dissolved in acetylacetone. Then monoethanolamine (MEA) and acetic acid ($CH_3COOH$) were added to the solution. The molar concentration of indium was kept as 0.1 mol concentration and the amount of Ti was varied according to weighting percent (0, 5, 10%). The complex solutions become clear and homogeneous after stirring for 24 hours. Heavily boron (p+) doped Si wafer with 100nm thermally grown $SiO_2$ serve as the gate and gate dielectric of the TFT, respectively. TiInO thin films were deposited using the sol-gel solution by the spin-coating method. After coating, the films annealed in a tube furnace at $500^{\circ}C$ for 1hour under oxygen ambient. The 5% Ti-doped InO TFT had a field-effect mobility $1.15cm^2/V{\cdot}S$, a threshold voltage of 4.73 V, an on/off current ratio grater than $10^7$, and a subthreshold slop of 0.49 V/dec. The 10% Ti-doped InO TFT had a field-effect mobility $1.03\;cm^2/V{\cdot}S$, a threshold voltage of 1.87 V, an on/off current ration grater than $10^7$, and a subthreshold slop of 0.67 V/dec.