• Title/Summary/Keyword: 부피분율

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Manufacturing and Characterization of SiC/AI Metal Matrix Composite by Modified Gas Metal Arc Welding Process ; Manufacturing and Microstructure (개조된 GMA용접공정을 이용한 SiC/AI 복합재료의 제조 및 특성)

  • Kim, Gwang-Su
    • Korean Journal of Materials Research
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    • v.6 no.11
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    • pp.1090-1098
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    • 1996
  • 개조한 가스 금속 아아크 용접공정을 이용하여 SiC/AI 금속기 복합재료를 제조하고 그 특성을 조사하였다. AI 모재위에 강화입자의 크기와 부피분율을 변화하여 다양한 SiC/AI 복합재료층을 제조하였고, 만들어진 복합재료층의 특성은 미세조직관찰과 미소경도시험을 통하여 이루어졌다. 복합재료층의 두께는 약 7-8mm로 측정되었고 균일한 강화입자의 분포도를 얻을 수 있었다. 분산입자의 부피분률은 Ar가스의 유량에 의하여 조절하였고 분산입자의 부피분률이 증가하고 크기가 작아짐에 따라 기지의 수지상 응고조직은 더욱 미세화되었다. 복합재료의 부피경도는 분산입자의 부피분률이 감소함에 따라 낮아졌으나 입자 크기에는 크게 변화가 없는 것으로 나타났다.

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A Study on Real Time Control of Resin Transfer Molding (RTM 공정의 실시간 제어에 관한 연구)

  • Jeon Young Jae;Um Moon Kwang;Byun Joon Hyung;Lee Woo Il
    • Composites Research
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    • v.18 no.4
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    • pp.35-43
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    • 2005
  • In resin transfer molding(RTM), race-track effects and non-uniform fiber volume fraction may cause undesirable resin flow patterns and thus result in dry spots, which affect the mechanical properties of the finished parts. In this study, a real time RTM control strategy to reduce these unfavorable effects is proposed. This control rule is accomplished by means of the permeability mapping and pressure regulation. Through numerical simulations, the validity of the proposed scheme is demonstrated.

The Effect of Mn Content Solution-treatment Temperatures on Insoluble Phases in Al-Li-Cu-Mg-Mn-Zr Alloys (Al-Li-Cu-Mg-Zr 합금의 미고용상에 미치는 용체화 처리 및 Mn 함량의 영향)

  • Shin, Hyun-Sik;Ming, He;Cho, Kwon-Koo;Chung, Young-Hoon;Shin, Myung-Chul
    • Analytical Science and Technology
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    • v.7 no.4
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    • pp.517-526
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    • 1994
  • Large insoluble phases and dispersoids in Al-Li-Cu-Mg-Mn-Zr alloys containing Mn were analyzed with EPMA(Electron Probe Microanalyzer) and SAEM(Scanning Auger Electron Microscope). Morphology, distribution and volume fraction of the large insoluble phase were also analyzed quantitatively by optical microscopy. Mechanical properties were tested at room temperature and at $200^{\circ}C$. With increasing Mn contents, the volume fraction of the large insoluble phases increased steeply, thus decreasing ductility. Mn was found to be very effective for obtaing uniformly distributed fine-grain structures. The alloy containing 0.44 wt% Mn showed the highest tensile strength among Mn-bearing alloys tested.

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Analysis of Stresses Along the Underfill/chip Interface (언더필/칩 계면의 응력 해석)

  • Park, Ji-Eun;Iwona Jasiuk;Lee, Ho-Young
    • Journal of the Microelectronics and Packaging Society
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    • v.9 no.4
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    • pp.35-45
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    • 2002
  • The stresses of the underfill/chip interface due to thermal loading was studied using the finite element method. At first, the effective properties of underfill for several volume fractions of silica particles were calculated by Mori-Tanaka method for three different material sets, and the parameters of singularity for the bimaterial edge and the bimaterial wedge were calculated. Consequently, the stresses at the underfill/chip interface with volume fraction of silica particles were investigated. Five different geometric models of flip-chip assembly involving two kinds of bimaterial strips and three kinds of three-layer models were considered under the assumption that the underfill is homogeneous. It was assumed that all components of the flip-chip assembly were linear elastic and isotropic, and their properties were temperature independent. The analysis was conducted in the context of the uncoupled plane thermo-elasticity under a plane strain assumption.

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Thermophysical Properties of PWB for Microelectronic Packages with Solder Resist Coating Process (마이크로 전자패키지용 Printed Wiring Board의 솔더레지스트공정에 따른 열적특성)

  • 이효수
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.3
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    • pp.73-82
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    • 2003
  • Recently, PWB(Printed Wiring Board) has been recognized in the field of microelectronic package as core technology for designing or manufacturing. PWB is the structure stacked by several materials with different thermophysical properties, which shows the different CTEs(Coefficient or Thermal Expansions) during the fabrication process and causes a lot of defects such as warpage, shrinkage, dimension, etc. Thermal deformation of PWB is affected mainly by the volume change of solder-resist among fabrication parameters. Therefore, thermal deformation of PBGA and CSP consisting of 2 layers and 4 layers was studied with solder-resist process. When over 30% in volume fraction of solder-resist, thermal deformation of 2-layered PWB was min. 40% higher than that of 4-layered PWB because 4-layered PWB contained the layer with high toughness such as prepreg, which counterbalanced the thermal deformation of solder-resist. Otherwise, when below 30%, PWB showed similar thermal deformation without regard to layers and design.

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Magnetic Properties of Nylon 6 based Nd-Fe-Co-Zr-B Pellets for Injection Molding (사출성형용 Nylon 6계 Nd-Fe-Co-Zr-B 펠렛의 자기특성)

  • 최승덕;이우영;양충진
    • Journal of the Korean Magnetics Society
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    • v.3 no.1
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    • pp.34-40
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    • 1993
  • Nylon 6 based magnetic pellets for injection molding were produced using plasma arc melt-spun $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ powders. Two sorts of bonded magnets made of two different sizes of particles ($38~75\;\mu\textrm{m}$ and $75~150\;\mu\textrm{m}$) were prepared to determine critical volume fraction of magnet powders, and the magnetic prop erties of the magnets were discussed as a function of density. For the nylon fi based Nd-Fe-Co-Zr-B pellets made of $38~75\;\mu\textrm{m}$ particles, the critical volume fraction of powders 0.7 was obtained with the pellet density which is 90% of theoretical density while the magnets of $75~150\;\mu\textrm{m}$ showed the density of 87% of the theoretical value with the same volume fraction. The nylon (i magnets with the addition of 0.5 wt. % silicon oil only exhibited the best magnetic properties to have $_{i}H_{c}=8.8\;kOe,\;B_{r}=5.1\;kG$ and $(BH)_{max}=5.2\;MGOe$ which are of world class. An empirical relationship in predicting the magnet density with a known fraction ($V_s$) of loading powders was obtained such as ${\rho}(g/cm^{3})=1.1+K.V_{s}$ where the K ranges over 5.3~5.6 be ing dependent upon the particle size loaded.

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Estimation of Rheological Properties of Highly Concentrated Polymer Bonded Explosive Simulant by Microstructure Analysis (미세구조 해석을 통한 고농축 복합화약 시뮬란트의 유변물성 예측)

  • Lee, Sangmook;Hong, In-Kwon;Lee, Jae Wook;Shim, Jung Seob
    • Polymer(Korea)
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    • v.38 no.2
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    • pp.225-231
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    • 2014
  • The rheological properties of highly concentrated polymer bonded explosive simulant were studied by using poly(ethylene-co-vinyl acetate) with 30 and 60% vinyl acetate (VA) content as a binder, respectively. Calcium carbonate and Dechlorane, whose physical properties are similar to resarch department explosive (RDX)'s, were used as fillers. The suspensions were mixed in a batch melt mixer and it was possible to fill 75 v% at maximum. From dynamic mechanical analysis, Dechlorane showed higher interaction with binder resins than that with calcium carbonate fillers. The effects of microstructural change on the rheological properties of the suspensions were investigated by a plate-plate rheometer with constant shear rate and constant shear stress modes, respectively. The theoretical maximum packing fraction of EVA31/Dechlorane suspension obtained from Krieger-Dougherty equation was 70 v% and it was thought that 2000 Pa was proper shear stress condition for this melt processing.

The Effect of Fabrication Process Parameters on the Microstructures of Intermetallic/Metal Laminated Composite by Self-propagating High-temperature Synthesis (자전고온반응에 의한 금속간화합물/금속 적층복합재료의 제조공정변수가 미세조직에 미치는 영향)

  • 김희연;정동석;홍순형
    • Composites Research
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    • v.16 no.3
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    • pp.68-74
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    • 2003
  • In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiA1$_3$ and was followed by the diffusional growth of Ni$_2$A1$_3$ between Ni and NiA1$_3$. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these 1aminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni$_3$Al having higher strength at room and high temperatures.

Effects of Aluminum Oxide Particles on the Erosion of Nozzle Liner for Solid Rocket Motors (고체 추진기관에서 산화알루미늄 입자가 노즐 내열재의 삭마에 미치는 영향)

  • 황기영;임유진;함희철
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.8
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    • pp.95-103
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    • 2006
  • The compositions, the gas properties in motor chamber and the aluminum oxide (Al2O3) particle size for two kinds of solid propellants with approximately 20% aluminum powder have been investigated. The SEM photographs of $Al_2O_3$ taken from nozzle entrance liner show that the aluminized PCP propellant with 47% volumetric fraction AP/HNIW and bimodal oxidizer 200-5 ${\mu}m$ can offer greater possibility for increasing aluminum agglomeration than the aluminized HTPB propellant with 64% volumetric fraction AP and trimodal oxidizer 400-200-6 ${\mu}m$. The nozzle entrance liner of solid rocket motor with the PCP propellant shows greater erosion at 4 circumferential sections in line with grain slots due to the impingement of large particles, but that with the HTPB propellant shows uniform erosion with circumferential angle.

Excess Volumes of Aqueous Solutions of Nonionic Amphiphile 2-(2-Hexyloxyethoxy)ethanol (비이온 양친매성 분자 2-(2-Hexyloxyethoxy)ethanol 수용액의 과잉 부피)

  • Lee, Jungno;Hwang, Yoonmi;Kang, Minhee;Lim, Kyung-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.37 no.3
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    • pp.516-525
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    • 2020
  • The densities of aqueous solutions of the amphiphile 2-(2-hexyloxyethoxy)ethanol (C6E2) were measured at 279.15 K and 282.15 K by vibrating-tube densitometry. Then using the density data of the binary C6E2 (1)/water(2) system, the excess volumes and partial molar volumes were determined at various compositions. Excess volume VE exhibits negative deviation for the whole region of composition, which implies relatively stronger attraction between molecules. At the C6E2 mole fraction of around 0.45, VE was at its minimum. Partial molar volume ${\bar{V}}_1$ increases monotonously with the mole fraction x1(=x) and ${\bar{V}}_2$ decreases with x. Any particular point in ${\bar{V}}_1$ and ${\bar{V}}_2$, which may point to molecular association, was unobserved.