This research presents a preparation method of dental components by metal injection molding process (MIM process) using titanium scrap. About 20 μm sized spherical titanium powders for MIM process were successfully prepared by a novel dehydrogenation and spheroidization method using in-situ radio frequency thermal plasma treatment. The effects of MIM process parameters on the mechanical and biological properties of dental components were investigated and the optimum condition was obtained. After sintering at 1250oC for 1 hour in vacuum, the hardness and the tensile strength of MIMed titanium components were 289 Hv and 584 MPa, respectively. Prepared titanium dental components were not cytotoxic and they showed a good cell proliferation property.

Synthesis of sub-micron 2SnO·(H2O) powders by chemical reduction process was performed at room temperature as function of viscosity of methanol solution and molecular weight of PVP (polyvinylpyrrolidone). Tin(II) 2-ethylhexanoate and sodium borohydride were used as the tin precursor and the reducing agent, respectively. Simultaneous calcination and sintering processes were additionally performed by heating the 2SnO·(H2O) powders. In the synthesis of the 2SnO·(H2O) powders, it was possible to control the powder size using different combinations of the methanol solution viscosity and the PVP molecular weight. The molecular weight of PVP particularly influenced the size of the synthesized 2SnO·(H2O) powders. A holding time of 1 hr in air at 500˚C sufficiently transformed the 2SnO·(H2O) into SnO2 phase; however, most of the PVP (molecular weight: 1,300,000) surface-capped powders decomposed and was removed after heating for 1 h at 700˚C. Hence, heating for 1 h at 500˚C made a porous SnO2 film containing residual PVP, whereas dense SnO2 films with no significant amount of PVP formed after heating for 1 h at 700˚C.

Carbon nanotube-dispersed bismuth telluride matrix (CNT/Bi2Te3) nanopowders were synthesized by chem- ical routes followed by a ball-milling process. The microstructures of the synthesized CNT/Bi2Te3 nanopowders showed the characteristic microstructure of CNTs dispersed among disc-shaped Bi2Te3 nanopowders with as an average size of 500 nm in-plane and a few tens of nm in thickness. The prepared nanopowders were sintered into composites with a homogeneous dispersion of CNTs in a Bi2Te3 matrix. The dimensionless figure-of-merit of the composite showed an enhanced value compared to that of pure Bi2Te3 at the room temperature due to the reduced thermal conductivity and increased electrical conductivity with the addition of CNTs.

In this paper, two kinds of advanced powder processing techniques Metal Injection Molding (MIM) and Direct Laser Forming (DLF) are introduced to fabricate complex shaped Ti alloy parts which are widely used for med- ical and aerospace applications. The MIM process is used to strengthen Ti-6Al-4V alloy compacts by addition of fine Mo, Fe or Cr powders. Enhanced tensile strength of 1030 MPa with 15.1% elongation was obtained by an addition of 4 mass%Cr because of the microstructural modification and also the solution strengthening in beta phase. However, their fatigue strength was lower compared to wrought materials, but was improved by HIP. Subsequently, the effect of feed- ing layer height (FLH) on the characteristics of the DLF compacts was investigated. In the case of 100 µm FLH, sur- face roughness was improved and nearly full density (99.8%) was obtained. Also, tensile strength of 1080 MPa was obtained, which is higher than the ASTM value.

Spherical Ti-6Al-4V powders in the size range of 250 and 300 µm were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.

In this study, we fabricated Nd2Fe14B hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of Nd2Fe14B. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentra- tions of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to con- trol the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of Nd2Fe14B phase and magnetic properties was investigated.

To improve coating ability and the life of the coating, Ti based composite materials with hydroxyapatite(HA) should be developed. The raw materials of Ti-26wt%, Nb-1wt%, and Si with 10wt% HA were mixed for 24 h by a mixing machine and milled for 1 h to 6 h by planetary mechanical ball milling. Ti-26%Nb-1%Si-(10%HA) composites, composed of nontoxic elements, were fabricated successfully by spark plasma sintering(SPS) at 1000˚C under 70MPa. The relative density of the sintered Ti-Nb-Si-HA composites using the 24 h mixed powder, and the 6 h milled powder, was 91% and 97 %, respectively. The effects of HA contents and milling time on microstructure and mechanical properties were investigated by SEM and hardness tester, respectively. The Vickers hardness of the composites increased with increasing milling time and higher HA content. The Young's modulus of the sintered Ti-26%Nb-1%Si-10%HA composite using the 6 h-milled powder was 55.6 GPa, as obtained by compression test. Corrosion resistance of the Ti-26wt%Nb-1wt%Si composite was increased by milling and by the addition of 10wt%HA. Wear resistance was improved with increasing milling time. Biocompatibility of the Ti-Nb-Si alloys was improved by the addition of HA.

A novel route to prepare Nd-Fe-B magnetic particles by utilizing both spray drying and reduction/diffu- sion processes was investigated in this study. Precursors were prepared by spray drying method using the aqueous solu- tions containing Nd salt, Fe salt and boric acid with stoichiometric ratios. Precursor particles could be obtained with various sizes from 2 to 10 µm by controlling concentrations of the solutions and the average size of 2 µm of precursors were selected for further steps. After heat treatment of precursors in air, Nd and Fe oxides were formed through desalt- ing procedure, followed by reduction processes in Hydrogen (H2) atmosphere and with Calcium (Ca) granules in Argon (Ar) successively. Moreover, diffusion between Nd and Fe occurred during Ca reduction and Nd2Fe14B particles were formed. With Ca amount added to particles after H2 reduction, intrinsic coercivity was changed from 1 to 10 kOe. In order to remove and leach CaO and residual Ca, de-ionized water and dilute acid were used. Acidic solutions were more effective to eliminate impurities, but Fe and Nd were dissolved out from the particles. Finally, Nd2Fe14B magnetic particles were synthesized after washing in de-ionized water with a mean size of 2 µm and their maximum energy prod- uct showed 9.23 MGOe.

Ultra-fine zirconium carbide (ZrC) powder with nano-sized primary particles was synthesized by the carbothermal reduction method by using nano-sized and nano-sized graphite powders mixture. The synthesized ZrC powder was well dispersed after simple milling process. After heat-treatment at for 2 h under vacuum, ultra-fine ZrC powder agglomerates (average size, ) were facilely obtained with rounded particle shape and particle size of ~200 nm. Ultra-fine ZrC powder with an average particle size of 316 nm was obtained after ball milling process in a planetary mill for 30 minutes from the agglomerated ZrC powder.

시판 유통 중인 고춧가루의 10종에 대해 미생물 (총 호 기성균수, 대장균군, 효모 & 곰팡이), 이화학적 품질 (수분 함량, pH, 기계적 색도 및 ASTA 색도, 입자 크기)을 확인 하였다. 시판 유통 중인 미생물 농도 측정결과, 총 호기성균, 효모 및 곰팡이는 103-106CFU/g 으로 나타났고, 대장 균군은 2종의 검체에서 103 CFU/g의 분포를 나타내었다. 수분함량은 7.25-12.73%로 나타나, 10종 모두 식품공전의 기준규격에 적합하였다. pH는 4.97~5.15 범위를 나타내어 시판 고춧가루의 건조방법은 각각 다른 것으로 판단되었다. 색도 측정결과 기계적 색도의 E 값은 최저 47.19, 최 고 58.04를 나타내었고, ASTA 색도는 최저 89.31, 최고 98.61로 나타나 제품별로 색도의 뚜렷한 차이가 나타났으나, 기계적 색도와 ASTA 색도의 상관성은 높지 않은 것으로 판단되었다. 고춧가루 10개 검체의 평균 입자크기는 605-1251 um로 나타났고, 분포도는 2종의 시료(RP-2, RP- 3)는 매우 균일한 분포도를 나타낸 반면, RP-9, RP-10은 가장 고르지 못한 분포도를 나타내었다.

phosphor powders were synthesized using a seed (average particle size: 5 ) by the polymer solution route. PVA solution was added to the sol precursors consisting of the seed powder and metal nitrate salts for homogeneous mixing in atomic scale. All dried precursor gels were calcined at and then heated at in atmosphere. The final powders were characterized by using XRD, SEM, PSA, PL and PKG test. All synthesized powders were crystallized to YAG phase without intermediate phases of YAM or YAP. The phosphor properties and morphologies of the synthesized powders were strongly dependent on the PVA content. Finally, the synthesized phosphor powder heated at , which is prepared from 12:1 PVA content and has an average particle size of 15 , showed similar phosphor properties to a commercial phosphor powder.

Nano Pd spot-coated active carbon powders were synthesized by a hydrothermal-attachment method (HAA) using PVP capped Pd colloid in a high pressure bomb at , 450 psi, respectively. The PVP capped Pd colloid was synthesized by the precipitation-redispersion method. PVP capped Pd nano particles showed the narrow size distribution and their particle sizes were less than 8nm in diameter. In the case of nano Pd-spot coated active carbon powders, nano-sized Pd particles were adhered in the active carbon powder surface by HAA method. The component of Pd was homogeneously distributed on the active carbon surface.

This paper describes the spherical ammonium diuranate gel particles which are the intermediated material of the microsphere for an VHTR(very high temperature reactor) nuclear fuel. The characteristics of the intermediate-ADU gel particles prepared by AWD(ageing, washing, and drying) and FB(fluidized-bed) apparatus were examined and compared in a sol-gel fabrication process. The electrical conductivity of washing filtrate from the FB treating and the surface area of dried-ADU gel particles were higher than those of AWD treating. Also, an internal pore volume in dried-ADU gel particles showed a more decrease in AWD treatment than FB treatment because of decomposition of PVA affected by the washing time. However, the internal microstructures of ADU gel particles were similar regardless of the process variation.

The purpose of this study is to investigate the crystalline structure and optical properties of (GaZn)(NO) powders prepared by solid-state reaction between GaOOH and ZnO mixture under NH3 gas flow. While ammoniation of the GaOOH and ZnO mixture successfully produces the single phase of (GaZn)(NO) solid solution within a GaOOH rich composition of under 50 mol% of ZnO content, this process also produces a powder with coexisting (GaZn)(NO) and ZnO in a ZnO rich composition over 50 mol%. The GaOOH in the starting material was phase-transformed to α-, β-Ga2O3 in the NH3 environment; it was then reacted with ZnO to produce ZnGa2O4. Finally, the exchange reaction between nitrogen and oxygen atoms at the ZnGa2O4 powder surface forms a (GaZn)(NO) solid solution. Photoluminescence spectra from the (GaZn)(NO) solid solution consisted of oxygen-related red-emission bands and yellow-, green- and blue-emission bands from the Zn acceptor energy levels in the energy bandgap of the (GaZn)(NO) solid solutions.

Silica-based ceramic-matrix composites have shown promise as advanced materials for many applications such as chemical catalysts, ceramics, pharmaceuticals, and electronics. SiO2-CuO-CeO2 multi-component powders and their thin film, using an oxalic acid template as a chelating agent, have larger surface areas and more uniform pore size distribution than those of inorganic acid catalysts. SiO2-CuO-CeO2 composite powders were synthesized using tetraethylorthosilicate, copper (II) nitrate hemi (pentahydrate), and cerium (III) nitrate hexahydrate with oxalic acid as template or pore-forming agent. The process of thermal evolution, the phase composition, and the surface morphology of these powders were monitored by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffractometry (XRD), field-emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectrometry (EDXS). The mesoporous property of the powders was observed by Brunner-Emmett-Teller surface (BET) analysis. The improved surface area of this powder template with oxalic acid was 371.4m2/g. This multi-component thin film on stainless-steel was prepared by sol-gel dip coating with no cracks.

The ultra-fine and less agglomerated titanium carbonitride particles were successfully synthesized by magnesiothermic reduction with low feeding rate of solution. The sub-stoichiometric titanium carbide () particles were produced by reduction of chlorine component by liquid magnesium at of gaseous and the heat treatments in vacuum were performed for 5 hours to remove the residual magnesium and magnesium chloride mixed with produced . The final particle with near 100 nm in mean size and high specific surface area of was obtained by nitrification under nitrogen gas at for 2 hrs.

A novel chemical method was evaluated to fabricate the ultrafine tungsten heavy alloy powders with bater-base solution made from the ammonium metatungstate (AMT), iron(II) chloride tetrahydrate (), nickel(II) chloride hexahydrate () as source materials and the sodium tungstate dihydrate () as Cl-reductant. In the preparation of mixtures the amounts of the source components were chosen so as to obtain alloy of 93W-5Ni-2Fe composition(wt.%). The obtained powders were characterized by X-ray diffraction, XRF, field-emission scanning microscope (FESEM), and chemical composition was analyzed by EDX.

In this study, electrolytic copper powders were consolidated by high-pressure torsion process (HPT) which is the most effective process to produce bulk ultrafine grained and nanocrystalline metallic materials among various severe plastic deformation processes. The bulk samples were manufactured by the HPT process at 2.5 GPa and 1/2, 1 and 10 turns. After 10 turns, full densification was achieved by high pressure with shear deformation and ultrafine grained structure (average grain size of 677 nm) was observed by electron backscatter diffraction and a scanning transmission electron microscope.

본 연구는 포장방법과 저장기간에 따른 국산대두와 연해주 대두의 이화학적인 특성을 조사하기 위하여 TBA test, 산가, POV, fluorescence spectrum test를 실시하였다. 저장 기간이 경과함에 따라 TBA test는 국산대두와 연해주 대두 모두 실험기간 내 포장방법에 따른 유의적인 차이는 있었으나 전체적인 경향은 차이가 없었다. 산가는 국산 대두에서 16일차에 유의미한 차이를 보였으나 20일차에서는 모두 유의차를 보이지 않는 것을 알 수 있었다. 연해주 대두의 경우 저장기간 동안 포장방법에 따른 차이가 없었다. POV의 경우 국산대두에서 저장 16일차까지 유의한 차이가 없었으나 진공포장 20일차에서 1.85 meq/kg oil로 값이 증가하였다. 연해주 대두에서는 초기값과 저장 20일차의 측정값이 10%내의 변화를 보이고 함기포장과 진공포장, 질소충진포장과의 유의차를 나타내지 않아 포장법에 의한 산패도의 차이를 찾아내지 못하였다. Fluorescence spectrum test를 이용한 측정에서는 국산 대두의 경우 같은 경향을 나타내었다. 연해주 대두의 경우도 저장방법 별 산패도 값의 차이는 존재하였지만 같은 경향을 나타내는 것을 알 수 있었다. 연구결과를 토대로 fluorescence spectrum test를 이용하여 산패도를 측정하는데 적합하다고 판단된다. 또한 요오드가, 검화가, 비중 측정을 통해 포장방법과 저장기간을 통한 변화를 측정하였으나 유의할 만한 차이를 나태내지 못하였다. 결과적으로 국산대두와 연해주대두의 저장기간 20일 동안의 산패도의 증가는 나타나지 않았고 포장방법에 따른 산패도의 차이는 없었다. 본 연구의 결과는 연해주산 대두를 수입할 경우 유통기한 중 질소충진과 같은 고비용의 포장법을 적용하지 않더라도 수입 시에 품질변화가 거의 이루어 지지 않음을 보여 주어 실질적으로 국내 소비자에게 연해주산 non-GMO 대두를 경제적으로 공급이 가능함을 보여주었다. 또한 20일의 저장기간 동안 변화가 매우 적음은 현재 대두의 분말가공에 시도되고 있는 집결지 최소가공방식의 최소가공량을 2-3배 확장하여 집결지에서 보다 많은 양을 가공 저장하여 수송함이 가능함을 보여 주고 있다. 이는 연해주대두의 경제적 활용가능성을 보다 높여 줄 것이라 판단된다.

In the present work, Al- composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of sizes ( , 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al- composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm added compact, it showed the highest values of compaction density and hardness compared with the conditions of and 500 nm additions, leading to the enhancement its mechanical properties.