• 제목/요약/키워드: rapid heating

검색결과 394건 처리시간 0.026초

마이크로웨이브 폴리올 공정에서 금속 도핑 산화아연 나노클러스터의 합성 (Synthesis of Metal Doped ZnO Nanoclusters by Microwave Assisted Polyol Process)

  • 권오산;강국현;이동규
    • 한국응용과학기술학회지
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    • 제31권3호
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    • pp.525-533
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    • 2014
  • 금속이 도핑 된 산화아연 나노클러스터를 합성하기 위해 마이크로웨이브를 이용한 폴리올 공정은 빠르고 경제적인 합성 방법이다. 디에틸렌글리콜은 높은 분극률과 마이크로파의 흡수 능력이 뛰어나며, 높은 온도상승 비율과 반응시간을 짧게 해준다. 본 연구에서는 금속이 도핑 된 산화아연 나노클러스터를 합성하기 위해서 첨가되는 seed의 부피비를 다르게 하여 얻었으며, 전구체로는 아세트산 아연 2수화물, 도핑 금속은 아세트산 금속 염을 그리고 용매로서 디에틸렌글리콜을 사용하였다. 금속이 도핑된 산화아연 클러스터는 FE-SEM, XRD, Raman, PSA로 특성을 확인하였다.

고주파 열처리 온도에 따른 선조질강의 인장특성 (Tensile Properties of Energy Saving Wire (ESW) with respect to Temperatures of High Frequency Induction Heat Treatment)

  • 이진범;강남현;박지태;안순태;박영도;최일동;남대근;조경목
    • 대한금속재료학회지
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    • 제48권11호
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    • pp.974-980
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    • 2010
  • Various types of steel, namely, 0.35C, 0.2C-Cr, and 0.2C-Cr-Mo steels, were quenched and tempered by high-frequency induction heat treatment. The type, size, and spheroidization of the carbides varied depending on the tempering temperatures ($450{\sim}720^{\circ}C$). During the tempering process, the carbide was precipitated in the martensite matrix. The 0.35C, 0.2C-Cr, and 0.2C-Cr-Mo steels contained carbides that were smaller than 120 nm. The carbide was spheroidized as the tempering temperature increased. Owing to the fine microstructure and spheroidization of the carbides, all three steels had a high tensile strength as well as yield ratio and reduction of area. In the case of the 0.2C-Cr steel, the use of Cr as an alloying element facilitated the precipitation of alloyed carbides with an extremely small particle and resulted in an increase in the spheroidization rate of the carbides. As a result, a large reduction of area was achieved (>70%). The 0.2C-Cr-Mo steel had the highest tensile strength because of the high hardenability that can be attributed to the presence of alloying elements (Cr and Mo). Quenching and tempering steels by induction heat treatment resulted in a high strength of over 1 GPa and a large reduction of area (>70%) because of the rapid heating and cooling rates.

방전플라즈마 소결 공정을 이용한 스퍼터링 타겟용 타이타늄 소결체 제조 및 특성 평가 (Fabrication and Evaluation Properties of Titanium Sintered-body for a Sputtering Target by Spark Plasma Sintering Process)

  • 이승민;박현국;윤희준;양준모;우기도;오익현
    • 대한금속재료학회지
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    • 제49권11호
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    • pp.845-852
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    • 2011
  • The Spark Plasma Sintering(SPS) method offers a means of fabricating a sintered-body having high density without grain growth through short sintering time and a one-step process. A titanium compact having high density and purity was fabricated by the SPS process. It can be used to fabricate a Ti sputtering target with controlled parameters such as sintering temperature, heating rate, and pressure to establish the optimized processing conditions. The compact/target(?) has a diameter of ${\Phi}150{\times}6.35mm$. The density, purity, phase transformation, and microstructure of the Ti compact were analyzed by Archimedes, ICP, XRD and FE-SEM. A Ti thin-film fabricated on a $Si/SiO_2$ substrate by a sputtering device (SRN-100) was analyzed by XRD, TEM, and SIMS. Density and grain size were up to 99% and below $40{\mu}m$, respectively. The specific resistivity of the optimized Ti target was $8.63{\times}10^{-6}{\Omega}{\cdot}cm$.

W-1.5 ZrO2 복합재료 합성과 급속소결 (Synthesis and Rapid Consolidation of W-1.5 ZrO2 Composite)

  • 김성은;손인진
    • 한국재료학회지
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    • 제28권11호
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    • pp.653-658
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    • 2018
  • $ZrO_2$ is a candidate material for hip and knee joint replacements because of its excellent combination of biocompatibility, corrosion resistance and low density. However, the drawback of pure $ZrO_2$ is a low fracture toughness at room temperature. One of the most obvious tactics to cope with this problem is to fabricate a nanostructured composite material. Nanomaterials can be produced with improved mechanical properties(hardness and fracture toughness). The high-frequency induction heated sintering method takes advantage of simultaneously applying induced current and mechanical pressure during sintering. As a result, nanostructured materials can be achieved within very short time. In this study, W and $ZrO_2$ nanopowders are mechanochemically synthesized from $WO_3$ and Zr powders according to the reaction($WO_3+3/2Zr{\rightarrow}W+3/2ZrO_2$). The milled powders are then sintered using high-frequency induction heating within two minutes under the uniaxial pressure of 80MPa. The average fracture toughness and hardness of the nanostructured W-3/2 $ZrO_2$ composite sintered at $1300^{\circ}C$ are $540kg/mm^2$ and $5MPa{\cdot}m^{1/2}$, respectively. The fracture toughness of the composite is higher than that of monolithic $ZrO_2$. The phase and microstructure of the composite is also investigated by XRD and FE-SEM.

FDM 3D 전도성 프린팅 어닐링 조건 따른 전기적 특성 연구 (Study on Electrical Characteristics of FDM Conductive 3D Printing According to Annealing Conditions)

  • 이선곤;김용래;유태정;박지혜;김주형
    • 한국기계가공학회지
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    • 제17권6호
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    • pp.53-60
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    • 2018
  • In this paper, the effect of different 3D printing parameters including laminated angle and annealing temperature is observed their effect on FDM conductive 3D printing. In FDM 3D printing, a conductive filament is heated quickly, extruded, and then cooled rapidly. FDM 3D Print conductive filament is a poor heat conductor, it heats and cools unevenly causing the rapid heating and cooling to create internal stress. when the printed conductive specimens this internal stress can be increase electrical resistance and decrease electrical conductivity. Therefore, This experiment would like to use annealing to remove internal stress and increase electrical conductivity. The result of experiment when 3D printing conductive specimen be oven cooling of annealing temperature $120^{\circ}C$ electrical resistance appeared decrease than before annealing. So We have found that 3D printing annealing removes internal stresses and increases the electrical conductivity of printed specimens. These results are very useful for making conductive 3D printing electronic circuit, sensor ect...with electrical conductance suitable for the application.

저항소자를 이용한 휴대형 Real-time PCR 기기용 히터 제작 (Design of an Inexpensive Heater using Chip Resistors for a Portable Real-time Microchip PCR System)

  • 최형준;김정태;구치완
    • 전기전자학회논문지
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    • 제23권1호
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    • pp.295-301
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    • 2019
  • 바이오샘플의 DNA를 대량 증폭할 수 있는 휴대형 실시간 중합효소연쇄반응(Real-time PCR) 기기에서 히터는 PCR 반응 온도를 제어하기 위한 중요한 요소 중의 하나이다. 보통 빠른 히팅을 위해 소형 PCR 칩에 집적화되어 있고, 반도체 공정을 이용하여 박막형태로 제작되어 PCR 칩 제작 단가가 높은 편이다. 따라서 본 연구에서는 값싸고 온도제어를 정확히 할 수 있는 히터로 칩 저항을 사용하는 것을 제안한다. 칩 저항을 사용한 히터는 구조가 단순하고 제작이 쉽다는 장점이 있다. $2.54{\times}2.54cm^2$ 크기의 실시간 PCR 칩 위에 칩 저항을 1개 또는 2개를 사용했을 때 온도분포를 시뮬레이션 하였고, 고른 온도분포를 갖는 PCR 칩을 제작했다. 또한 효율적인 PCR 칩 냉각을 위해 소형 fan이 내장된 하우징을 설계하였고, 3D 프린터로 제작했다. 온도제어는 마이크로프로세서를 이용한 PID제어법(Proportional-Integral-Differential control)을 적용했다. 온도상승비와 하강비는 각각 $18^{\circ}C/s$, $3^{\circ}C/s$이며, 각 PCR 반응 단계의 유지 시간을 30초로 하였을 때, 한 사이클은 약 2.66분이 걸렸고, 35 사이클은 약 93 분 내로 진행할 수 있었다.

BIM 기반 에너지성능분석을 통한 공동주택의 주동 설계 전략개발 - 주동타입 및 층수 변화를 중심으로 - (Multi-Family Housing Block Design Strategy Development by BIM-based Energy Performance Analysis - focusing on the Block Types and the Variations in Stories -)

  • 전재홍;박혜진;이권형;추승연
    • 대한건축학회논문집:계획계
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    • 제34권2호
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    • pp.3-11
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    • 2018
  • Korea has achieved a rapid economic development and with the increase in population and national income and the expansion of social and economic activities, energy consumption has rapidly increased too. Energy consumption per head has constantly increased and currently, power consumption per head is 7.5 times bigger than in 1985. Buildings occupy 25% of total energy consumption and especially, 50% of total energy is consumed for heating and cooling. In this situation, multi-family housing, which has constantly been increased, has an energy saving rate of 1.9%, which is the lowest level and this makes the government's energy policy for sustainable energy system development useless. Besides, energy consumption leads to secondary problems, such as air, water and marine pollution and heat pollution and wastewater/drainage and the increased use of fossil fuel is a fundamental reason for ozone layer destruction and global warming. Therefore, efficient energy consumption plans are required. This study aims to analyze energy performance in each block type of high-rise and diversified multi-family housing that accounts for 60% of all the housing forms, depending on the variations in stories through BIM-based energy simulation. For this study, four representative block types were selected, based on the multi-family floor plan, which is certified for energy performance evaluation and they were applied to the floor plan of a multi-family house that is scheduled to be built. Then BIM modeling was conducted from the fifth story to the 40th story at an intervals of 5 stories and based on the finding, energy characteristics of each block type and energy performance depending on the variations in stories were analyzed. It is considered that this would serve as objective data for block type and block story decision of energy performance-based multi-family housing.

스마트 웨어러블용 NiTi계 선형 형상기억합금을 이용한 소프트 텍스타일 액추에이터 제작 및 동적 특성 측정 (Fabrication of Soft Textile Actuators Using NiTi Linear Shape Memory Alloy and Measurement of Dynamic Properties for a Smart Wearable)

  • 김상운;김상진;김주용
    • 한국의류학회지
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    • 제44권6호
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    • pp.1154-1162
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    • 2020
  • In this study, the soft textile actuator is produced for a smart wearable with the shape memory effects from linear shape memory alloys of Nickel and Titanium using the driving force through the fabrication process. The measurement model was designed to measure dynamic characteristics. The heating method, and memory shape of the linear shape memory alloy were set to measure the operating temperature. A shape memory alloy at 40.13℃, was used to heat the alloy with a power supply for the selective operation and rapid reaction speed. The required amount of current was obtained by calculating the amount of heat and (considering the prevention of overheating) set to 1.3 A. The fabrication process produced a soft textile actuator using a stitching technique for linear shape memory alloys at 0.5 mm intervals in the general fabric. The dynamic characteristics of linear shape memory alloys and actuators were measured and compared. For manufactured soft textile actuators, up to 0.8 N, twice the force of the single linear shape memory alloy, 0.38 N, and the response time was measured at 50 s.

기계적 활성화된 분말로부터 고주파유도 가열 연소합성에 의한 나노구조 Mg2SiO4-MgAl2O4 복합재료 제조 및 기계적 특성 (Mechanical Properties and Fabrication of Nanostructured Mg2SiO4-MgAl2O4 Composites by High-Frequency Induction Heated Combustion)

  • 손인진;강현수;홍경태;도정만;윤진국
    • 대한금속재료학회지
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    • 제49권8호
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    • pp.614-618
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    • 2011
  • Nanopowders of MgO, $Al_2O_3$ and $SiO_2$ were made by high energy ball milling. The rapid sintering of nanostructured $MgAl_2O_4-Mg_2SiO_4$ composites was investigated by a high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Highly dense nanostructured $MgAl_2O_4-Mg_2SiO_4$ composites were produced with simultaneous application of 80MPa pressure and induced output current of total power capacity (15 kW) within 2min. The sintering behavior, gain size and mechanical properties of $MgAl_2O_4-Mg_2SiO_4$ composites were investigated.

PREDICTING MALTING QUALITY IN WHOLE GRAIN MALT COMPARED TO WHOLE GRAIN BARLEY BY NEAR INFRARED SPECTROSCOPY

  • Black, Cassandra K.;Panozzo, Joseph F.
    • 한국근적외분광분석학회:학술대회논문집
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    • 한국근적외분광분석학회 2001년도 NIR-2001
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    • pp.1618-1618
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    • 2001
  • Predicting quality traits using near infrared (NIR) spectroscopy on whole grain samples has gained wide acceptance as a non-destructive, rapid and cost effective technique. Barley breeding programs throughout southern Australia currently use this technology as a tool for selecting malting quality lines. For the past 3 years whole grain barley calibrations have been developed at VIDA to predict malting quality traits in the early generation selections of the breeding program. More recently calibrations for whole grain malt have been developed and introduced to aid in selecting malted samples at the mid-generation stage for more complex malting quality traits. Using the same population set, barley and malt calibrations were developed to predict hot water extracts (EBC and IoB), diastatic power, free $\alpha$-amino nitrogen, soluble protein, wort $\beta$-glucan and $\beta$-glucanase. The correlation coefficients between NIR predicted values and laboratory methods for malt were all highly significant ($R^2$ > 0.84), whereas the correlation coefficients for the barley calibrations were lower ($R^2$ > 0.57) but still significant. The magnitude of the error in predicting hot water extract, diastatic power and wort $\beta$-glucan using whole grain malt was reduced by 50% when compared with predicting the same trait using whole grain barley. This can be explained by the complex nature of attempting to develop calibrations on whole grain barley utilizing malt data. During malting, the composition of barley is modified by the action of enzymes throughout the steeping and germination stages and by heating during the kilning stage. Predicting malting quality on whole grain malt is a more reliable alternative to predicting whole grain barley, although there is the added expense of micro-malting the samples. The ability to apply barley and malt calibrations to different generations is an advantage to a barley breeding program that requires thousands of samples to be assessed each year.

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