• Title/Summary/Keyword: Aging Epoxy

Search Result 100, Processing Time 0.021 seconds

Aging Characteristics of Composite Materials in Carbody of Tilting Train using Accelerated Aging Test (가속노화시험을 이용한 틸팅차량 차체 복합재의 노화특성)

  • Yoon Sung-Ho;Kim Yong-Goo;Nam Jung-pyo;Shin Kwang-Bok;Koo Dong-Hoe
    • Proceedings of the KSR Conference
    • /
    • 2003.10c
    • /
    • pp.333-338
    • /
    • 2003
  • Polymeric composite structures used in ground transportation applications such as the carbody of tilting train may be exposed to a ground environmental conditions during long-term missions. In this study, the degradation of mechanical and physical properties of graphite/epoxy composite and glass fabric/phenol composite under ground environmental conditions was investigated. Accelerated environmental conditions of ultraviolet radiation, temperature, and moisture were considered. Several types of specimens were used to investigate the effects of environmental conditions on mechanical properties of the composites. Also, storage shear modulus, loss shear modulus, and tan 8 were measured as a function of exposure times through a dynamic mechanical analyzer. Finally, composite surfaces exposed to environmental conditions were examined using a scanning electron microscope.

  • PDF

A Study on Insulation Diagnosis by Partial Discharge Spectroscopy of Generator Stator Winding (발전기 고정자 권선의 부분방전 특성을 이용한 절연진단 연구)

  • Kang, D.S.;Kim, Y.J.;Kim, K.Y.
    • Proceedings of the KIEE Conference
    • /
    • 1993.07b
    • /
    • pp.584-587
    • /
    • 1993
  • Mica, which have a good thermal and electrical characteristics, while will cleave easily at these layers. In order to bond mica materials soldily, mica/epoxy composite insulation materials were developed for generator stator winding. There are lots of problems such as delamination and partial discharge of these insulation materials caused by mechanical, electrical and thermal aging. Several experiments have been conducted in order to find the useful diagnostic parameters from the partial discharge phenomena by applying a new measurement techniques. this paper deals with the partial discharge pulse characteristics, which may be a useful diagnostic concept in predicting insulation condition of generator stator insulation materials. Long term insulation aging test shows that partial discharge phase angle an magnitude are identified as one of the main key techniques for insulation diagnosis on generator stator winding.

  • PDF

Evaluation of Bond Strength of Isothermally Aged Plasma Sprayed Thermal Barrier Coating (플라즈마 용사 열차폐 코팅의 열화에 따른 접착강도 평가)

  • Kim, Dae-Jin;Lee, Dong-Hoon;Koo, Jae-Mean;Song, Sung-Jin;Seok, Chang-Sung;Kim, Mun-Young
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.32 no.7
    • /
    • pp.569-575
    • /
    • 2008
  • In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. For each aging condition, bond tests for three samples were conducted for evaluating degradation of adhesive or cohesive strength of thermal barrier coating system. For as-sprayed condition, the location of fracture in the bond test was in the middle of epoxy which have bond strength of 57 MPa. As specimens are degraded by thermal aging, bond strength gradually decreased and the location of failure was also changed from within top coat at the earlier stage of thermal aging to the interface between top coat and TGO at the later stage due to the delamination in the coating.

Natural Aging Effect on the Fiber Tensile Strength of Carbon Epoxy Pressure Vessel (자연 노화에 따른 카본 에폭시 압력용기의 섬유 인장 강도 변화)

  • Hwang, Tae-Kyung;Park, Jae-Byum;Kim, Hyoung-Geun;Doh, Young-Dae
    • Composites Research
    • /
    • v.20 no.2
    • /
    • pp.1-9
    • /
    • 2007
  • To evaluate and investigate the aging characteristics and the structural service lifetime of the CFV(carbon fiber pressure vessel), natural aging tests were carried out using the CFVs, which had been placed and aged at outdoor and indoor laboratories for 10 and 15 years, respectively. To obtain the probabilistic characteristics of ageing characteristics in aged CFVs, inner pressure loading test was conducted with ring specimens taken from aged CFVs. And, to observe the interface morphology of aged CFVs, the micro-photographs were taken by SEM microscope and the fractured interfaces between the carbon fiber and the matrix resin were scrutinized. Based on the Weibull parameters of the tensile failure strain of aged CFVs, the degradation of the 10 and the 15 year aged CFV occur by 19% and 23%, respectively, and the effect of the placement, whether being placed inside the laboratory or not, is not so significant. However, the outer layer protection, such as painting, is found very advantageous to prevent CFV from aging.

A Study on the Thermal Degradation Properties of Epoxy Resin for Cast Resin Transformer (몰드변압기용 에폭시 수지의 열 열화특성에 관한 연구)

  • Lim, Kyung-Bum;Nam, Ki-Dong;Kim, Ki-Hwan;Park, Su-Hong;Hwang, Myung-Hwan
    • Fire Science and Engineering
    • /
    • v.22 no.2
    • /
    • pp.44-48
    • /
    • 2008
  • In this paper, we measured a contact angle, surface resistivity and XPS to study the thermal aging characteristics of the epoxy resin for cast resin transformer. As a result of this experiment, we found that the contact angle increases up to $200^{\circ}C$ as it causes a re-crosslinking on the surface, but starts decreasing at $250^{\circ}C$ as it causes heat condensation. As a result of examining the oxygen/carbon peaks through the XPS analysis, we obtained a higher oxygen peak vs. carbon in the first untreated sample, but it showed the opposite trend after heat treatment. That rise in the carbon peak continued up to $200^{\circ}C$, but decreased again at the temperatures above. That's because it kept forming a stable surface structure up to $200^{\circ}C$ but its carbon combination got destroyed due to a rapid oxidization at $250^{\circ}C$. And a conduction path was formed easily with the hydrophile property caused by rapid surface activation.

Interfacial and Mechanical Properties of Glass Fiber Reinforced Epoxy Composites with Different Crosslinking Density after Saline Water Aging (기지재의 가교밀도에 따른 유리섬유 복합재료의 염수노화 후 계면 및 기계적 물성)

  • Shin, Pyeong-Su;Kim, Jong-Hyun;Baek, Yeong-Min;Park, Ha-Seung;Kwon, Dong-Jun;Park, Joung-Man
    • Composites Research
    • /
    • v.31 no.5
    • /
    • pp.186-191
    • /
    • 2018
  • Condition and properties of composites with different chemical structure of epoxy matrix were observed after saline solution treatment. Epoxy was used as matrix and the flexibility was controlled by using 2 typed-epoxies and 3 types hardeners (amine, acid anhydride and amide). Saline water treatment was conducted with 6 wt% NaCl solution at $60^{\circ}C$ for 0, 15, and 30 days. Cross section was observed and interfacial and mechanical and properties was evaluated. Amine type exhibited the highest crosslinking density and mechanical and interfacial properties whereas water absorbance was lowest. It is because that the water molecules can be hardly penetrate into the epoxy matrix or the interface between epoxy and glass fiber and it leads to saline water resistance of composites.

A Study on the Development and Dielectric Properties of Insulating Materials for Super-Conductor -For Matrix of Composite Materials- (초전도체 절연용 재료의 전기적 절연 특성과 개발에 관한 연구-복합 재료의 매트릭스에 대하여-)

  • 조정수;최세원;김종경;이규철;이종호
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.38 no.7
    • /
    • pp.511-523
    • /
    • 1989
  • This paper investigates physical properties, the electrical and mechanical characteristics of the epoxy resin with different curing methods and postcuring conditions at room temperature or cryogenic temperature (LN2). According to the results in this paper, first, it is found that the physical properties, electrical and mechanical characteristics of the epoxy resin are largely affected by the interior reaction temperature on the curing. Thus, in the fabrication of the sample, several excellent characteristics of the sample are obtained by controlling the interior reaction temperature of the epoxy resin. Second, the sample having optimal electrical and mechanical characteristics is obtained for the repetitive post-curing method at 100c in view point of the post-curing conditions of the epoxy resin. Third, it appears that tan and characteristics at LN2 temperature are about half of those at room temperature. Fourth, it appears that the dielectric strength of the epoxy resin at LN2 temperature is higher by about 0.6-1.0 MV/cm than that at room temperature. The heat-aging of the epoxy resin due to the micro-defect and excess fever-movement have been noticed to affect dielectric strength at LN2 temperature more significantly than at room temperature.

Fracture Mechanics Analysis of Cracked Plate Repaired by Patch(II) - The Analysis of Debonding Effect - (보강재로 보수된 균열평판의 파괴역학적 해석(II)-분리 영향에 대한 연구-)

  • Jeong, Gi-Hyeon;Yang, Won-Ho;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.9 s.180
    • /
    • pp.2246-2251
    • /
    • 2000
  • Adhesive bonding repair methods has been used for a number of decades for construction of damaged structures. In order to evaluate the life of cracked aging aircraft structures, the repair technique which uses adhesively bonded boron/epoxy composite patches is being widely considered as a cost-effective and reliable method. But, this repair method contains many shortcomings. One of these shortcomings, debonding is major issue. When the adhesive shear stress increases, debonding is caused at the end of patch and plate interface. And this debonding is another defect except cracks propagation. In this paper, we assess safety at the cracked AI-plate repaired by Br/Epoxy composite patch. Firstly, from the view of fracture mechanics, reduction of stress intensity factors is determined by the variety of patch feature. Secondly, using the elastic analysis and finite element analysis, the distribution of adhesive shear stresses is acquired. Finally, The problem of how to optimize the geometric configurations of the patch has been discussed.

Measurement of CTE Change in a Composite Laminate with Aging under Space Environment using Fiber Optic Sensors (광섬유센서를 이용한 우주환경하에서 복합재료 적층시편의 노화에 따른 열팽창계수변화 측정)

  • Gang,Sang-Guk;Gang,Dong-Hun;Kim,Cheon-Gon;Hong,Chang-Seon
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.31 no.10
    • /
    • pp.21-26
    • /
    • 2003
  • In this research, the change of coefficient of thermal expansion (CTE) of graphite/epoxy composite laminate under space environment was measured using fiber optic sensors. Two fiber Bragg grating (FBG) sensors have been adopted for the simultaneous measurement of thermal strain and temperature. Low Earth Orbit (LEO) conditions with high vacuum, ultraviolet and thermal cycling environments were simulated in a thermal vacuum chamber. As a pre-test, a FBG temperature sensor was calibrated and a FBG strain sensor was verified through the comparison with the electric strain gauge (ESG) attached on an aluminun specimen at high and low temperature respectively. The change of the CTE in a composite laminate exposed to space environment was measured for intervals of aging cycles in real time. As a whole, there was no abrupt change of the CTE after 1000 aging cycles. After aging, however, the CTE decreased a Little all over the test temperature range. These changes are caused by outgassing, moisture desorption, matrix cracking etc.

The Study on the Weathering Characteristics about Epoxy Adhesive for the Adhesion and Restoration of Metallic Cultural Assets (금속문화재 접합 복원용 에폭시 접착제의 내후성 연구)

  • Lee, Ji-Hyun;Wi, Koang-Chul
    • Journal of Conservation Science
    • /
    • v.26 no.1
    • /
    • pp.61-67
    • /
    • 2010
  • After selecting five types of adhesive epoxy resin for metallic cultural assets such as $Araldite^{(R)}$ rapid type, $Devcon^{(R)}$, $Araldite^{(R)}$ SV427+HV427, $CDK^{(R)}$520, $Araldite^{(R)}$ AW106+HV953 which had already been studied, this paper approached more closely the problem of yellowing and the signal of aging with time passing by connecting the problems with the safety of metallic cultural assets. The change of physical properties according to the change of state of epoxy adhesives was investigated through the change of flexural strength and the change of surface hardness by artificially providing the possible environmental change factors such as ultra-violet ray, and acid base, and how the epoxy chemically changes in its ingredients by the environment was analyzed through FT-IR. As a result of the experiment, for the most part of adhesives brought about the physical change of flexural strength, the change of surface hardness, and the chemical change of chemical ingredients as the product of alcohol, which were respectively different according to the time of ultraviolet irradiation, and acid base change. Under most of the conditions, SV427+HV427 and $CDK^{(R)}$520 were fairly stabilized under each condition of weatherability, but it seems that they should be refrained from being applied in case that the area to restore is thin and wide because the degree of flexural strength of themselves is low. Also, it is found that the preservation environment is very important not only for artifacts but also for the preservation of resins sused for preservation treatment.