The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was compared with the cast Mg-1.0 wt%Zn alloy. All coatings consisting of MgO and oxides showed porous and coarse surface features with some volcano top-like pores distributed disorderly and cracks between pores. In particular, the surface of coatings on Mg-1.0 wt%Zn-2.0 wt%Y alloy showed smaller area of pores and cracks compared to the Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn alloys. The cross section micro-hardness of coatings on the gas atomized Mg-Zn-Y alloys was higher than that on the cast Mg-1.0 wt%Zn alloy. Additionally, the coated Mg-1.0 wt%Zn-2.0 wt%Y alloy exhibited the best corrosion resistance in 3.5%NaCl solution. It could be concluded that the addition of Y has a beneficial effect on the formation of protective and hard coatings on Mg alloys by plasma electrolytic oxidation treatment.

The purpose of this article is to examine the relationship between unsafe behavior, human factor and human error. For the object, several correlation analyses for those three elements were implemented. Several hypotheses for the relationship between them was suggested. The suggested hypotheses were verified by a comprehensive survey received from 132 safety manager of manufacturing industry. The conclusions were proven from the hypotheses verificaiton as belows; 1) The dependent relation items between unsafe behavior and human factor are dress protection tool, machine(equipment) and working rule have a dependent relation. 2) The dependent relation items between human factor and human error are uncommunication, control, slaps, fatigue, education, system, unmonitoring, failure. 3) The dependent relation items between human error and unsfafe behavior are decline and product/working method,failure and uncommunication have a dependent relation.

Ag-Cu alloy nano powders were fabricated by the electrical explosion of Cu-plated Ag wires. Ag wires of 0.2mm diameter was electroplated to final diameter of 0.220 mm and 0.307 mm which correspond to Ag-27Cu and Ag-68Cu alloy. The explosion product consisted of equilibrium phases of and -Cu. The particle size of Ag-Cu nano powders were 44 nm and 70 nm for 0.220 mm and 0.307 mm wires, respectively. The Ag-Cu nano powders contained less Cu than average value due to higher sublimation energy compared to that of Ag. As a result, micron-sized spherical particles formed from liquid droplets contained higher Cu content.

Pure WC or WC with low Co concentration less than 0.5 wt.% is studied to fabricate high density WC/Co cemented carbide using vacuum sintering and post HIP process. Considering the high melting point of WC, it is difficult to consolidate it without the use of Co as binder. In this study, the effect of lower Co addition on the microstructure and mechanical properties evolution of WC/CO was investigated. By HIP process after vacuum sintering, hardness and density was sharply increased. The hardness values was using binderless WC.

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

The present study was focused on the synthesis of a dispersed copper matrix composite material by the combination of the mechanical milling and plasma activated sintering processes. The mixed powder was prepared by the combination of the mechanical milling and reduction processes using the copper oxide and titanium diboride powder as the raw material. The synthesized mixed powder was sintered by the plasma activated sintering process. The hardness and electric conductivity of the sintered bodies were measured using micro vickers hardness and four probe method, respectively. The relative density of composite material sintered at showed about 98% of theoretical density. The composite material has a hardness of about 130Hv and an electric conductivity of about 85% IACS. The hardness and electric conductivity of composite material were about 140 Hv and about 45% IACS, respectively.

Ordered to FePt nanoparticles are strong candidates for high density magnetic data storage media because the phase FePt has a very high magnetocrystalline anisotropy , high coercivity and chemical stability. In this study, the ordered FePt nanoparticles were successfully fabricated by chemical vapor condensation process without a post-annealing process which causes severe particle growth and agglomeration. The nanopowder was obtained when the mixing ratio of Fe(acac) and Pt(arac) was 2.5 : 1. And the synthesized FePt nanoparticles were very fine and spherical shape with a narrow size distribution. The average particle size of the powder tended to increase from 5 nm to 10 nm with increasing reaction temperature from to . Characterisitcs of FePt nanopowder were investigated in terms of process parameters and microstructures.

BaTiO3 powders were prepared by sol-gel method from different concentration of KOH aqueous solution and Ba/Ti molar ratio. Particle shape, size and crystal structure of prepared BaTiO3 powders were analyzed by SEM, XRD, and FT-IR. As the result of KOH concentration changing, spherical particles were obtained by condition more than 3 M and particle size decreased as concentration increasing. Different appearance showed between dried and sintered powders against changing of Ba/Ti molar ratio. In case of dried powders, the crystallinity decreased as molar ratio increasing. On the other hand, increased as molar ratio increasing in case of sintered powders.

Eu3+ doped YGdO3 phosphors particles which have fine size and narrow size distribution with non aggregated uniform morphology were prepared by solvent evaporation method for the improvement of emission efficiency. Several parameters have been investigated in this study such as the influences of composition ratio of host materials, calcination temperature, amount of activator, surfactant, pH and flux on the photoluminescence intensity, particle size and dispersion. Eu3+ doped YGdO3 phosphor presented a strong narrow band emission peak at 612nm. The maximum emission intensity ofYGdO3:Eu3+ occurred when Eu3+ concentration is 3wt% under vacuum ultra violet excitation. Prepared phosphors were found to have small round-shaped particles about 150nm in size. The addition of PVA as a surfactant inhibits the grain growth and the agglomeration of particles efficiently by reducing the oxygen bridge bonds. As the pH reduces, PL intensity increase due to reducing the formation of oxygen bridge bonds. The particles prepared from solvent evaporation method with 5wt% LiCl were found to have 120% PL intensity compare to particles prepared without LiCl flux.

본 연구에서는 충전용 이차전지의 분리막으로 쓰이는 다공성 막을 기존의 분리막 재료보다 뛰어난 물성을 나타내는 PVdF(poly(vinylidene fluoride))를 사용하여 상전이 방법으로 제조하였다. 용매인 DMF(N,N-dimethylformamide)에 PVdF를 단일상으로 녹인 후 깨끗한 유리판에 캐스팅하여 막을 얻었다. 얻어진 분리막에서 가장 높은 공극률은 78.6%로 얻어졌다. UTM(universal testing machine)을 이용하여 측정된 분리막의 인장강도는 PVdF 20 wt%에서 5.16 MPa의 값을 나타내었다. 시차주사현미경(scanning electron microscopy, SEM)을 이용하여 분리막의 단면 관찰을 통해 다공성을 확인하였다.

In T-mixer crystallization, supersaturation is generated by mixing of another solvent or non-solvent in order to reduce the solubility of the compound. Also, T-mixer is a type of continuous crystallization. In order to induce micro-mixing, two solutions were mixed rapidly by T-mixer, which formed high supersaturation. As the results, mean size of HMX crystals decreased with increasing de-supersaturation rate (Rs). Eventually, HMX particles ranging from 0.5 to 5μm can be obtained by T-mixer crystallization. Mixing efficiency in T-mixer increased with increasing Rs values. In T-mixer crystallization without surfactants, homogeneous nucleation was formed when S and Rs was over 54 and 1.6×103/sec. In T-mixer crystallization with surfactants, homogeneous nucleation was formed when S and Rs was over 26 and 7.4/sec.

침지침강 상변환법으로 폴리에테르설폰(PES)-TiO2 복합막을 제조하였다. 14 wt% 및 20 wt%의 PES/NMP 기준 고분자 용액에 TiO2 나노입자를 PES에 대해 0~60 wt%로 첨가량을 달리하여 복합막 제조에 사용될 캐스팅 용액을 준비하였다. 제조된 PES-TiO2 복합막의 막 특성과 몰폴로지를 TiO2 첨가량에 따른 캐스팅 용액의 점도, coagulation value, 광투과도와 복합막의 인장강도, 세공크기 및 접촉각, 표면 및 단면 SEM 사진, BSA 용액의 한외여과 실험을 통해 규명하였다. 캐스팅 용액에 첨가시킨 TiO2 입자의 함유량이 증가함에 따라 점도는 증가하고 coagulation value는 낮아져 캐스팅 용액의 열역학적 불안정성이 증가하였다. TiO2 입자의 첨가량이 증가함에 따라 1) 순간분리의 침강형식을 유지하면서 침강속도가 빨라졌으며, 2) 순수투과량, 세공크기 및 압밀화 안정성이 증가하며, 3) 인장강도와 접촉각은 감소하였다. PES-TiO2 복합막의 BSA 용액에 대한 전량여과식 한외여과 실험결과 TiO2 입자의 함유량이 증가함에 따라 막의 친수화 특성이 증가하여 투과플럭스가 증가하였으며, TiO2가 첨가되지 않은 막과 비교하여 최대 7배까지 투과 플럭스가 향상되었다.