• 제목/요약/키워드: hardening effect

검색결과 751건 처리시간 0.032초

Micro-hardening 원소 첨가가 전해동박의 기계적 특성에 미치는 영향 (Effect of Micro-hardening Additive on the Mechanical Property of Electroplated Copper Foil)

  • 박성철;손성호;김진화;김형미;이호년;이홍기
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2014년도 추계학술대회 논문집
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    • pp.122-122
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    • 2014
  • 본 연구에서는 micro-hardening을 통한 고강도 고연성 전해동박을 제조하기 위해 Sn, Co, Zn 등의 원소 첨가량, 전류밀도, 전해액 온도, 첨가제 제어 등의 공정조건 변화에 따른 전해동박층의 표면 형상, 조성 및 전기전도도를 평가하였고, 인장강도와 연신율을 평가하였다.

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Observation for Machinability of Hardening Particle Dispersed Iron Based Sintered Alloy

  • Tamori, Ryo;Ishihara, Naoshi
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.301-302
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    • 2006
  • Machinability and machining mechanism were examined in the case where resin impregnation treatment was conducted to the Mo-Co hardening particle dispersed iron-based sintered alloy. As a result, the force required for machining decreased significantly compared with the case where resin impregnation treatment was not conducted. This effect is considered to be attributable to the embrittlement of cutting chips produced by the minimization of the cut material deformation.

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판재의 소성변형 거동을 동정하기 위한 새로운 응력-변형률 모델 (New Stress-Strain Model for Identifying Plastic Deformation Behavior of Sheet Materials)

  • 김영석;팜콕트완;김찬일
    • 한국정밀공학회지
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    • 제34권4호
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    • pp.273-279
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    • 2017
  • In sheet metal forming numerical analysis, the strain hardening equation has a significant effect on calculation results, especially in the field of spring-back. This study introduces the Kim-Tuan strain hardening model. This model represents sheet material behavior over the entire strain hardening range. The proposed model is compared to other well known strain hardening models using a series of uniaxial tensile tests. These tests are performed to determine the stress-strain relationship for Al6016-T4, DP980, and CP Ti sheets. In addition, the Kim-Tuan model is used to integrate the CP Ti sheet strain hardening equation in ABAQUS analysis to predict spring-back amount in a bending test. These tests highlight the improved accuracy of the proposed equation in the numerical field. Bending tests to evaluate prediction accuracy are also performed and compared with numerical analysis results.

생쥐 난자 배양시의 자발적 투명대 경화 현상과 PMA에 의한 투명대 경화 현상 비교 (The Comparison of the Spontaneous Zona Pellucida Hardening and PMA-induced Zona Pellucida Hardening during in Vitro Culture of the Mouse Oocytes)

  • 강혜나;배인하;김해권
    • Clinical and Experimental Reproductive Medicine
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    • 제21권1호
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    • pp.99-110
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    • 1994
  • One consequence of fertilization in mammals is an increased resistance of the zona pellucida (ZP) to proteases and various chemical reagents. This phenomenon has been called 'zona pellucida hardening' (ZPH), and it is generally accepted that it is caused by the secretory products of cortical granules released by the egg at fertilization. ZP of mouse oocytes maturing in vitro in a chemically defined medium becomes progressively more resistant to solubilization by chymotrypsin ("Spontaneous" ZP hardening). In the present study, it was aimed to find the specificity of spontaneous ZPH in relation to its possible relevance to the cortical reaction and the physiological block to polyspermy. When a maturation inhibitors, cAMP analog(dbcAMP) and phosphodiesterase inhibitor (IBMX) was added to culture medium, it prevent spontaneous ZPH of mouse oocyte during in vitro culture. Thus spontaneous ZPH requires GVBD, since it is prevented by those agents, which inhibit GVBD in vitro. However, culture for 3 hours in the presence of PMA(lOng/ml), a protein kinase C activator, resulted in ZPH without GVBD, thus suggesting that ZPH may be regulated independently apart from the event of GVBD. Pretreatment of mouse oocyte with FBS result in partially inhibitory effect on subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhibitory effect on the spontaneous ZPH, but subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhinbitory effect on the spontaneous ZPII, but had no inhibitory effect on PMA-induced ZPH. Treatment with a microfilament formation blocker(cytochalasin-B) at 1${\mu}g$/ml concentration, resulted in the excellent inhibitory effect on spontaneous ZPH. However cytochalasin-B did not inhibit PMA-induced ZPH. Thus this suggesting that spontaneuse ZPH had a different mechanism from PMA-induced ZPH.

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양생온도가 긴급 보수용 폴리머 모르타르의 역학적 특성에 미치는 영향 (Effect of Curing Temperature on Mechanical Properties of Polymer Mortar for Urgent Repairing)

  • 조용인;홍기남;김민성;박재규
    • 한국안전학회지
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    • 제31권5호
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    • pp.109-116
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    • 2016
  • This study presents the results of experiments to investigate the effect of polymer type and curing temperature on the mechanical properties of polymer mortar. Setting time of two types of polymers, hardening-delayed polymer(HDP) and rapid hardening polymer(RHP), was tested to check the working time. Additionally, flexural strength, compressive strength, and splitting tensile strength was investigated for mortars using these polymers. From these results, it was confirmed that, irrespective to curing temperature, RHP mortar at the curing age of 24h develops the similar mechanical properties to maximum properties and HDP mortar is more sensitive to the curing temperature. In addition, it should be noted that RHP mortar and HDP mortar are suitable in winter and summer, respectively.

구상흑연주철의 마이크로 펄스 플라즈마 질화에 미치는 공정변수의 영향에 관한 연구 (A study on the Effect for Process Parameters on the Micro-pulse Plasma Nitriding of Ductile Cast Iron)

  • 김무길;이철민;권성겸;정병호;이재식;유용주;김기준
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권3호
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    • pp.43-51
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    • 2000
  • The effect of time, temperature and gas composition on the case hardened thickness, hardness and nitride formation in the surface of ductile cast iron(GCD400) have been studied by micro-pulse plasma technique. Typically, external compound layer and internal diffusion layer which is much thicker than compound layer was observed in the nitride hardening of ductile cast iron. The relative amount kind of phases formed in the nitrided hardening changed with the change of nitriding conditions. Generally, only nitride phases such as $\gamma^'$($Fe_4N$), or $\varepsilon$($Fe_{2-3}N$) phases were detected in compound layer by XRD analysis. The thickness of compound layer increased with the increase of nitrogen content in the gas composition. The optimum nitriding temperature was obtained at $520^{\circ}C$. The nitrided hardening thickness parabolically with nitriding time(t) and thus, the case hardened layer(d) fits well with the typical parabolic equation ; d=kt. The material constant k for GCD400 nitrided at $520^{\circ}C$ was $0.04919\times10^3{\mu}m.hr^{-1/2}$.

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Numerical modeling of soil nail walls considering Mohr Coulomb, hardening soil and hardening soil with small-strain stiffness effect models

  • Ardakani, Alireza;Bayat, Mahdi;Javanmard, Mehran
    • Geomechanics and Engineering
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    • 제6권4호
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    • pp.391-401
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    • 2014
  • In an attempt to make a numerical modeling of the nailed walls with a view to assess the stability has been used. A convenient modeling which can provide answers to nearly situ conditions is of particular significance and can significantly reduce operating costs and avoid the risks arising from inefficient design. In the present study, a nailing system with a excavation depth of 8 meters has been modeled and observed by using the three constitutive behavioral methods; Mohr Coulomb (MC), hardening soil (HS) and hardening soil model with Small-Strain stiffness ensued from small strains (HSS). There is a little difference between factor of safety and the forces predicted by the three models. As extremely small lateral deformations exert effect on stability and the overall deformation of a system, the application of advanced soil model is essential. Likewise, behavioral models such as HS and HSS realize lower amounts of the heave of excavation bed and lateral deformation than MC model.

5052-O 알루미늄 합금의 워터 캐비테이션 피닝 시간에 따른 표면 경화와 부식 특성에 관한 연구 (Investigation on surface hardening and corrosion characteristic by water cavitation peening with time for Al 5052-O alloy)

  • 김성종;현광룡
    • Corrosion Science and Technology
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    • 제11권4호
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    • pp.151-156
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    • 2012
  • The cavity formed by the ultrasonic generation in the fluid with the application of water cavitation peening collides into the metal surface. At this time, the surface modification effect such as the work hardening presents by the compressive residual stress formed due to the localized plastic deformation. In this investigation, the water cavitation peening technology in the distilled water with the lapse of time was applied to 5052-O aluminum alloy for aluminum ship of a high value. So, the optimum water cavitation peening time on the effect for surface hardening and anti-corrosion property was investigated. Consequently, the water cavitatin peening time on excellent hardness and corrosion resistance characteristic presented 3.5 min. and 5.0 min, respectively. The surface hardness in the optimum water cavitation peening time was improved approximately 45% compared to the non-WCPed condition. In addition, corrosion current density was decreased.

하이브리드 박막/굽힘 방법을 이용한 드로비드력의 예측 (Prediction of Drawbead Restraining Force by Hybrid Membrane/Bending Method)

  • 이명규;정관수;;금영탁
    • 소성∙가공
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    • 제15권8호
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    • pp.533-538
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    • 2006
  • A simplified numerical procedure to predict drawbead restraining forces(DBRF) has been developed based on the hybrid membrane/bending method which superposes bending effects onto membrane solutions. As a semi-analytical method, the new approach is especially useful to analyze the effects of various constitutive parameters. The present model can accommodate general anisotropic yield functions along with non-linear isotropic-kinematic hardening under the plane strain condition. For the preliminary results, several sensitivity analyses for the process and material effects such as friction, drawbead depth, hardening behavior including the Bauschinger effect and yield surface shapes on the DBRF are carried out.

$CO_2$ 레이저 분산빔에 의한 표면경화가 구상흑연주철의 피로특성에 미치는 영향 (Effects of surface hardening by using $CO_2$ laser defocussed beam on the fatigue resistance of ductile irons)

  • 박근웅;한유희;이상윤
    • 한국레이저가공학회지
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    • 제2권2호
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    • pp.42-51
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    • 1999
  • This study has been performed to investigate into some effects of the output power and traverse speed of laser beam on the microstructures, hardness and fatigue resistance of the ductile iron surface-hardened by $CO_2$ laser defocussed beam. Optical micrographs have shown that with increasing the output power and decreasing the traverse speed, the martensite was coarsened and some retained austenite were appeared in ductile iron. The microstructures of hardening zone were composed of bull's eye and some nodular graphite dissolved structures by the effect of self quenching. Fatigue fracture characteristics of ductile iron have appeared in the high stress and low stress ranges. The fracture initiated at nodular graphites in the surface hardened layer due to the stress concentration caused by a notch effect. The interior graphite nodules were broken away or popped out during crack propagation. Fatigue test has shown that values of fatigue strength considerably increased with increasing output power at a given traverse speed.

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