• Title/Summary/Keyword: epoxy molding

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온도 변화에 따른 Nano/Micro $SiO_2$ 혼합 Epoxy의 체적고유저항 특성

  • Kim, Jeong-Sik;Jeong, In-Beom;Ryu, Bu-Hyeong;Kim, Gwi-Yeol;Hong, Jin-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.153-153
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    • 2009
  • In the study the volume resistivity Characteristics of epoxy resin using nano and micro filler, nano and micro filler are made from insulating material epoxy resin using for transformer equipment and molding several devices as changing amount of addition of diameter 12 [nm] and 7 [${\mu}m$] $SiO_2$, we measured volume resistivity of nano and micro filler by High Resistance Meter(4329A). As the result of measurement, When is micro filler, the volume resistivity continuously increased over 80 [$^{\circ}$].

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An Analysis of Insulating Reliability in Epoxy Composites for Molding Materials of PT

  • Yang, Jeong-Yun;Park, Geon-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.09a
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    • pp.43-46
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    • 2001
  • The DC dielectric breakdown of epoxy composites used for transformer was experimented and then its data were simulated by Weibull distribution equation in this study. The more hardener increased the stronger breakdown strength at low temperature because of cross-linked density by the virtue of ester radical, and the breakdown strength of specimens with filler was lower than it of non-filler specimens because it was believed that the adding filler formed interface, charges were accumulated in it, the molecular mobility was raised, the electric field was concentrated, electrons were accelerated and then electron avalanche was early accomplished. From the analysis of Wei bull distribution equation, it was confirmed that as the allowed breakdown probability was· given by 0.1[%], the value of 'applied field was needed to be under 17.20[kV/mm].

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A Study on the Characteristics of New Type of Composite Bipolar Plate for the PEM Fuel Cell (고분자전해질 연료전지용 새로운 타입의 복합재료 분리판의 특성연구)

  • Kim, Jong-Wan;Lee, Jin-Sun;Sun, Kyung-Bok;Lee, Joong-Hee
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.180-183
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    • 2009
  • Composite bipolar plates offer several advantages of low cost, light weight, and ease of manufacturing compared to traditional graphite plate. However, it is difficult to achieve both high electrical conductivity and high flexural strength. In this study, the hybrid carbons filled epoxy composite bipolar plates were fabricated to test electrical conductivity and flexural properties. Graphite powders were used as the main conducting filler and continuous carbon fiber fabrics were inserted to improve the mechanical properties of the composite. This hybrid composite showed improved in-plane electrical conductivity and flexural property. The moldability of the hybrid composite was also improved comparing to the continuous prepreg composite. This study suggested that the continuous carbon fiber inserted graphite/epoxy composites can be a potential candidate material to overcome the disadvantages of conventional graphite composite or continuous prepreg composite bipolar plates.

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Analyses of Fracture Surfaces after Pull-out Test: Brown Oxide (Pull-out 시험 후의 표면분석 : 갈색산화물)

  • Lee, H.Y.;Kim, S.R.
    • Journal of Surface Science and Engineering
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    • v.34 no.2
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    • pp.142-150
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    • 2001
  • Due to naturally formed copper oxides, the adhesion strength between copper and epoxy resin is often very poor. To improve the adhesion strength between copper and epoxy resin, Cu-based leadframe sheets were oxidized in a brown-oxide forming solution. Then the effect of brown-oxide formation on the adhesion strength of leadframe to epoxy molding compound (EMC) was studied using pull-out specimens. After the pull-out test, fracture surfaces were analyzed using SEM, AES and EDS to determine failure path. The results showed that the failure path lay over inside the CuO and inside the EMC irrespective of the pull strength.

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Multi-stage Compression Molding Technology of Fast Curing CF/Epoxy Prepreg (속경화용 탄소섬유/에폭시 프리프레그의 다단 압축 성형기술)

  • Kwak, Seong-Hun;Mun, Ji-Hun;Hong, Sang-Hwui;Kwon, Soon-Deok;Kim, Byung-Ha;Kim, Tae-Yong
    • Composites Research
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    • v.34 no.5
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    • pp.269-276
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    • 2021
  • PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

Failure Paths of Polymer/Roughened Metal Interfaces under Mixed-Mode Loading (혼합 하중하에서의 고분자/거친금속 계면의 파손경로)

  • Lee Ho-Young;Kim Sung-Ryong
    • Korean Journal of Materials Research
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    • v.14 no.5
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    • pp.322-327
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    • 2004
  • Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

The Thermal Analysis of Pole Mount Mold Transformer with One-body Molding by Duct Condition (일체형 주상용 몰드 변압기의 덕트에 따른 열해석 특성 연구)

  • 조한구;이운용;박영두
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.348-352
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    • 2004
  • The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and ow loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

A Study on the Manufacture of Gas Insulated Switchgear Spacer Using APG Molding Process (APG 주형방식을 이용한 가스절연개폐기용 절연 스페이서 제작에 관한 연구)

  • Lee, Chanyong;Bae, Jaesung;Cho, Han-Gu;Lee, Sangmook;Lee, Jaehyeong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.4
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    • pp.386-391
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    • 2022
  • The gas insulation switchgear, which is a device for protecting a power system, cannot be supported by the insulation gas itself in a charge unit stored in a metal container. Therefore, molding technology is required to manufacture a gas insulation switch spacer. The APG method injection molding simulation was performed by applying the variables obtained through the physical properties of an epoxy composite used for manufacturing an insulating spacer to a moldflow software. After varying the temperature conditions of heater in the simulation, the thermal characteristics and the degree of hardening of the spacer were analyzed, based on which the optimum process conditions are presented.

Measurement of Adhesion Strength between Oxidized Cu-based Leadframe and EMC (산화처리된 구리계 리드프레임과 EMC 사이의 접착력 측정)

  • Lee, Ho-Young;Yu, Jin
    • Korean Journal of Materials Research
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    • v.9 no.10
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    • pp.992-999
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    • 1999
  • Due to the inherently poor adhesion strength of Cu-based leadframe/EMC(Epoxy Molding Compound) interface, popcorn-cracking phenomena of thin plastic packages frequently occur during the solder reflow process. In this study, in order to enhance the adhesion strength of Cu-based leadframe/EMC interface, brown-oxide layer was formed on the leadframe surface by immersing of leadframe sheets in hot alkaline solution, and the adhesion strength of leadframe/EMC interface was measured by using SDCB(Sandwiched Double Cantilever Beam) and SBN(Sandwiched Brazil-Nut) specimens. Results showed that brown oxide treatment of leadframe introduced fine acicular CuO crystals on the leadframe surface and improved the adhesion strength of leadframe/EMC interface. Enhancement of adhesion strength was directly related to the thickening kinetics of oxide layer. This might be due to the mechanical interlocking of fine acicular CuO crystals into EMC.

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Bond Strength of Carbon Fiber Sheet on Concrete Substrate Processed by Vacuum Assisted Resin Transfer Molding

  • Uddin, N.;Shohel, M.;Vaidya, U.K.;Serrano-Perez, J.C.
    • Advanced Composite Materials
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    • v.17 no.3
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    • pp.277-299
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    • 2008
  • High quality and expedient processing repair methods are necessary to enhance the service life of bridge structures. Deterioration of concrete can occur as a result of structural cracks, corrosion of reinforcement, and freeze.thaw cycles. Cost effective methods with potential for field implementation are necessary to address the issue of the vulnerability of bridge structures and how to repair them. Most infrastructure related applications of fiber-reinforced plastics (FRPs) use traditional hand lay-up technology. The hand lay-up is tedious, labor-intensive and relies upon personnel skill level. An alternative to traditional hand lay-up of FRP for infrastructure applications is Vacuum Assisted Resin Transfer Molding (VARTM). VARTM uses single sided molding technology to infuse resin over fabrics wrapping large structures, such as bridge girders and columns. There is no work currently available in understanding the interface developed, when VARTM processing is adopted to wrap fibers such as carbon and/or glass over concrete structures. This paper investigates the interface formed by carbon fiber processed on to a concrete surface using the VARTM technique. Various surface treatments, including sandblasting, were performed to study the pull-off tensile test to find a potential prepared surface. A single-lap shear test was used to study the bond strength of CFRP fabric/epoxy composite adhered to concrete. Carbon fiber wraps incorporating Sikadur HEX 103C and low viscosity epoxy resin Sikadur 300 were considered in VARTM processing of concrete specimens.