• 제목/요약/키워드: 적층구

검색결과 121건 처리시간 0.021초

수계 바인더를 이용한 NiCuZn Ferrite의 슬러리 제조 (The Preparation of NiCuZn Ferrite Slurry Using the Water Mixed Binder System)

  • 류병환;이정민;고재천
    • 자원리싸이클링
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    • 제7권4호
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    • pp.35-42
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    • 1998
  • 오늘날 전자부품 산업에 실장기술은 크게 각광을 받고 있다. 페라이트 칩인덕터와 같이 전자부품의 소형화를 위해서는, 쉬트 적층법이나 스크린 인쇄법 등을 위하여 유기용매를 사용하는 세라믹 습식공정이 널리 사용되고 있다. 본연구에서는 물이 혼합된 용매계를 이용한 NiCuZn Ferrite(NCZF) 슬러리와 그린쉬트의 제조 및 평가에 관한 연구를 하였다. 볼밀링에 의하여 21 vol%의 NCZF 슬러리를 제조하였으며, polacrylic vinyl copolymer를 바인더로서 사용하였다. 용매로서는 isopropyl alcohol과 2-butoxy ethanol에 40∼80% 물을 혼합하여 사용하였다. 그 결과, NCZF 슬러리의 분산안정성은 입자의 정전기적 힘보다는 free polymer에 의해 나타났으며, 슬러리의 점성은 용매중의 물함량에 크게 의존하였다.

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음향방출법을 이용한 평판형 압전 복합재료 작동기의 파괴거동 해석 (Analysis of the Fracture Behavior of Plate-type Piezoelectric Composite Actuators by Acoustic Emission Monitoring)

  • 우성충;구남서
    • 비파괴검사학회지
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    • 제26권4호
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    • pp.220-230
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    • 2006
  • 3점 굽힘 하중을 받는 단일 PET 및 평판형 압전 복합재료 작동기(PCA)의 파괴거동을 음향방출(AE) 법을 이용하여 살펴보았다. 단일 PET의 경우 최대 굽힘하중에서 발생한 AE신호는 고진폭 및 긴 유지시간을 갖는 특징을 보였으며 FFT에 의한 지배 주파수 대역을 확인한 결과 $100{\sim}230kHz$의 비교적 저주파수 대역이었다. PCA의 경우, stage 1에서 발생한 80dB이상의 고진폭 및 $170{\sim}223kHz$의 저 지배 주파수 대역을 갖는 신호는 PZT층에서의 취성파괴 및 PZT층과 인근 섬유층 사이의 층간분리에 의한 것으로 추정되었다. 상기의 AE거동 해석결과와 광학현미경 및 주사전자현미경에 의한 손상관찰에 근거하여 비대칭으로 적층된 PCA의 파괴거동과 관련한 AE특성을 규명하였다.

랭뮤어-쉐퍼 기법 이용 생체모사 폴리도파민-산화그래핀 복합체 대면적 적층 기법 연구 (Large Area Deposition of Biomimetic Polydopamine-Graphene Oxide Hybrids using Langmuir-Schaefer Technique)

  • 김태호;송석현;조경일;구자승
    • 접착 및 계면
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    • 제20권3호
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    • pp.110-115
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    • 2019
  • 그래핀으로 박리시키기 위한 한 가지 방법으로 산화그래핀이 많은 관심이 집중되고 있다. 산화그래핀의 산화그룹은 다양한 기능기와 수소결합을 시킬 수 있어 여러 응용분야에 이를 적용시키기 위한 연구가 활발히 진행되고 있다. 하지만 산화그래핀 자체만으로는 실질적으로 응용에 요구되어지는 기계적 물성을 만족시킬 수 없다. 따라서 본 연구에서는 홍합 단백질을 생체모사한 폴리도파민을 이용하여 산화그래핀과 결합시키고 액체-기체 계면에서 대면적의 복합체막을 형성 시켰다. 또한 폴리도파민-산화그래핀 복합체 박막의 모폴로지 구조도 제어하여 나노 링클 구조를 가지는 복합체 막을 얻었다. 기계적으로 우수하며 정교한 나노 구조를 형성할 수 있어 차세대 해수담수화 멤브레인 또는 탄소 복합재료에 이용될 수 있을 것으로 기대될 수 있다.

하이브리드 탄소섬유 적층구조에 따른 복합재료의 기계적 특성 연구 (Study on the Mechanical Properties of Hybridized Carbon Fiber Composite According to Stacking Structure)

  • 구선웅;오우진;원종성;이하람;윤주영;이승구
    • 한국염색가공학회지
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    • 제30권4호
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    • pp.313-320
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    • 2018
  • As carbon fiber reinforced composites(CFRP) are widely used in aerospace, automobile, marine, and sports goods applications, they have been studied extensively by various researchers. However, CFRP have been pointed out because of machining problems such as delamination and burr phenomenons. Especially, hole machining process, drilling, has non-smooth features on inlet and outlet surfaces of drilled hole. This kind of machining problem can be controlled to some extent by using high modulus pitch-CF, which has considerable effects on fracture behavior of composite compared with only PAN CF composite. Therefore, PAN and pitch hybridized CF composites were prepared having high strength and modulus. The results demonstrate that the hybrid CFRP specimens with pitch CF offer the good potential to enhance modulus as well as strength properties. Dynamic mechanical, flexural, and impact properties were measured and analyzed. Morphological surface of the composites were also observed by IFS-28, canon after hole machining.

IN718 초내열 합금의 고속 적층 제조 속도 확보를 위한 최적 VED 활용 공정 변수 제어 방안 연구 (Study for the Process Parameter Control to Achieve High Build Rate of Laser Powder Bed Fused IN718 Super Alloy Using Optimal VED)

  • 김상욱;김규식;손용호;이기안
    • 한국분말재료학회지
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    • 제29권5호
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    • pp.390-398
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    • 2022
  • Recently, considerable attention has been given to nickel-based superalloys used in additive manufacturing. However, additive manufacturing is limited by a slow build rate in obtaining optimal densities. In this study, optimal volumetric energy density (VED) was calculated using optimal process parameters of IN718 provided by additive manufacturing of laser powder-bed fusion. The laser power and scan speed were controlled using the same ratio to maintain the optimal VED and achieve a fast build rate. Cube samples were manufactured using seven process parameters, including an optimal process parameter. Analysis was conducted based on changes in density and melt-pool morphology. At a low laser power and scan speed, the energy applied to the powder bed was proportional to ${\frac{P}{\sqrt{V}}}$ and not ${\frac{P}{V}}$. At a high laser power and scan speed, a curved track was formed due to Plateau-Rayleigh instability. However, a wide melt-pool shape and continuous track were formed, which did not significantly affect the density. We were able to verify the validity of the VED formula and succeeded in achieving a 75% higher build rate than that of the optimal parameter, with a slight decrease in density and hardness.

Methyltrichlorosilane 표면 처리를 통한 적층 제조용 AlSi10Mg 분말의 유동 특성 향상 공정 연구 (Improving Flow Property of AlSi10Mg Powder for Additive Manufacturing via Surface Treatment using Methyltrichlorosilane)

  • 박상철;김인영;김영일;김대겸;이기안;오승주;이빈
    • 한국분말재료학회지
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    • 제29권5호
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    • pp.363-369
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    • 2022
  • AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a high-quality additive manufacturing product.

다른 크기의 분말 적층을 통해 얻은 Fe-6%Mn합금의 경사 미세조직과 기계적 특성 (Gradient Microstructure and Mechanical Properties of Fe-6%Mn Alloy by Different Sized Powder Stacking)

  • 서남혁;이준호;신우철;전준협;박정빈;손승배;정재길;이석재
    • 한국분말재료학회지
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    • 제29권5호
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    • pp.382-389
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    • 2022
  • A typical trade-off relationship exists between strength and elongation in face-centered cubic metals. Studies have recently been conducted to enhance strength without ductility reduction through surface-treatment-based ultrasonic nanocrystalline surface modification (UNSM), which creates a gradient microstructure in which grains become smaller from the inside to the surface. The transformation-induced plasticity effect in Fe-Mn alloys results in excellent strength and ductility due to their high work-hardening rate. This rate is achieved through strain-induced martensitic transformation when an alloy is plastically deformed. In this study, Fe-6%Mn powders with different sizes were prepared by high-energy ball milling and sintered through spark plasma sintering to produce Fe-6%Mn samples. A gradient microstructure was obtained by stacking the different-sized powders to achieve similar effects as those derived from UNSM. A compressive test was performed to investigate the mechanical properties, including the yielding behavior. The deformed microstructure was observed through electron backscatter diffraction to determine the effects of gradient plastic deformation.

반응표면모델을 통한 적층제조된 ZrH2 접종제 첨가AA7075 합금의 균열 밀도 예측 (Prediction of Crack Density in additive manufactured AA7075 Alloy Reinforced with ZrH2 inoculant via Response Surface Method)

  • 이정아;최중호;김형섭
    • 한국분말재료학회지
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    • 제30권3호
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    • pp.203-209
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    • 2023
  • Aluminum alloy-based additive manufacturing (AM) has emerged as a popular manufacturing process for the fabrication of complex parts in the automotive and aerospace industries. The addition of an inoculant to aluminum alloy powder has been demonstrated to effectively reduce cracking by promoting the formation of equiaxed grains. However, the optimization of the AM process parameters remains challenging owing to their variability. In this study, the response surface methodology (RSM) was used to predict the crack density of AM-processed Al alloy samples. RSM was performed by setting the process parameters and equiaxed grain ratio, which influence crack propagation, as independent variables and designating crack density as a response variable. The RSM-based quadratic polynomial models for crack-density prediction were found to be highly accurate. The relationship among the process parameters, crack density, and equiaxed grain fraction was also investigated using RSM. The findings of this study highlight the efficacy of RSM as a reliable approach for optimizing the properties of AM-processed parts with limited experimental data. These results can contribute to the development of robust AM processing strategies for the fabrication of high-quality Al alloy components for various applications.

3차원 적층 제조 공정(DED) 기반 Al-6061+Al-12Si 합금 조합 실험 (Combinatorial Experiment for Al-6061 and Al-12Si alloy Based on Directed Energy Deposition (DED) Process)

  • 전서연;박수원;송용욱;박지원;박현영;이보람;최현주
    • 한국분말재료학회지
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    • 제30권6호
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    • pp.463-469
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    • 2023
  • Aluminum alloys, known for their high strength-to-weight ratios and impressive electrical and thermal conductivities, are extensively used in numerous engineering sectors, such as aerospace, automotive, and construction. Recently, significant efforts have been made to develop novel aluminum alloys specifically tailored for additive manufacturing. These new alloys aim to provide an optimal balance between mechanical properties and thermal/electrical conductivities. In this study, nine combinatorial samples with various alloy compositions were fabricated using direct energy deposition (DED) additive manufacturing by adjusting the feeding speeds of Al6061 alloy and Al-12Si alloy powders. The effects of the alloying elements on the microstructure, electrical conductivity, and hardness were investigated. Generally, as the Si and Cu contents decreased, electrical conductivity increased and hardness decreased, exhibiting trade-off characteristics. However, electrical conductivity and hardness showed an optimal combination when the Si content was adjusted to below 4.5 wt%, which can sufficiently suppress the grain boundary segregation of the α-Si precipitates, and the Cu content was controlled to induce the formation of Al2Cu precipitates.

Selective Laser Melting 방식으로 적층제조된 Inconel 718 합금의 조사 경화 특성 (Irradiation Hardening Property of Inconel 718 Alloy produced by Selective Laser Melting)

  • 서주원;임상엽;진형하;천영범;강석훈;한흥남
    • 한국분말재료학회지
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    • 제30권5호
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    • pp.431-435
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    • 2023
  • An irradiation hardening of Inconel 718 produced by selective laser melting (SLM) was studied based on the microstructural observation and mechanical behavior. Ion irradiation for emulating neutron irradiation has been proposed owing to advantages such as low radiation emission and short experimental periods. To prevent softening caused by the dissolution of γ' and γ" precipitates due to irradiation, only solution annealing (SA) was performed. SLM SA Inconel 718 specimen was ion irradiated to demonstrate the difference in microstructure and mechanical properties between the irradiated and non-irradiated specimens. After exposing specimens to Fe3+ ions irradiation up to 100 dpa (displacement per atom) at an ambient temperature, the hardness of irradiated specimens was measured by nano-indentation as a function of depth. The depth distribution profile of Fe3+ and dpa were calculated by the Monte Carlo SRIM (Stopping and Range of Ions in Matter)-2013 code under the assumption of the displacement threshold energy of 40 eV. A transmission electron microscope was utilized to observe the formation of irradiation defects such as dislocation loops. This study reveals that the Frank partial dislocation loops induce irradiation hardening of SLM SA Inconel 718 specimens.