• Title/Summary/Keyword: mechanical resistance

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Fabrication and evaluation of a micro heat flux sensor using thermopile (열전대를 이용한 미세 열유속 센서의 제작 및 평가)

  • Kim Jung-Hoon;Kim Bum-Seok;Cho Hyung-Hee;Kim Yong-Jun
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1210-1213
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    • 2005
  • Micro heat flux sensor is used in various industries to measure heat flux. In this study, a micro heat flux sensor is fabricated using the MEMS (Micro Electro Mechanical Systems) techniques. The fabricated sensor is composed in thermopile for sensor and SU-8 for thermal resistance layer. The new method of fabrication SU-8 is proposed in this study. The sensitivity is 44μV/(W/cm2)44μV/(W/cm2) at steady state and Reynolds number is 91322.

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Transition Mechanism from Brittle Fracture to Ductile Shear when Machining Brittle Materials with an Abrasive Waterjet

  • Huang, Chuanzhen;Zhu, Hongtao;Lu, Xinyu;Li, Quanlai;Che, Cuilian
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.2
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    • pp.11-17
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    • 2008
  • Critical erosion kinetic energy models for radial/median cracks and lateral cracks in a workpiece are established in this study. We used experimental results to demonstrate that the fracture erosion resistance and erosion machining number could be used to evaluate the brittle fracture resistance and machinability of a workpiece. Erosion kinetic energy models were developed to predict brittle fracture and ductile shear, and a critical erosion kinetic energy model was developed to predict the transition from brittle fracture to ductile shear. These models were verified experimentally.

Changes on the Abrasion and Mechanical Properties of Warp Knitted Fabric for Footwear with Softeners and Heat Treatments (유연제 및 열처리에 따른 신발용 경편성물의 마모 및 역학 특성 변화)

  • Jeon, Youn-Hee;Koo, Ja-Gil;Jeong, Won-Young;An, Seung-Kook
    • The Korean Fashion and Textile Research Journal
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    • v.12 no.4
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    • pp.494-499
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    • 2010
  • Knitted fabrics are very popular for their numerous advantages such as greater comfort, attractive garment appearance, better fit on the body, etc. In this study, we investigated the mechanical properties and abrasion property of warp knitted fabrics for footwear which treated with several softeners to improve abrasion resistance. The antistatic softener among the various softeners showed high improvement in abrasion resistance. Among the mechanical properties with treating conditions, WT (tensile energy), G (shear stiffness), B (bending rigidity) increased as treating timeincreased. But the other mechanical properties were little changed with treating concentration.

Study on the Damage Behavior of 304 Stainless Steel for Gas Boiler with Specific Resistance (비저항에 따른 가스보일러용 304스테인리스강재의 손상거동에 관한 연구)

  • Yun, Byoung-Du;Lim, Uh-Joh;Jeong, Ki-Cheol
    • Journal of the Korean Institute of Gas
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    • v.9 no.4 s.29
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    • pp.6-10
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    • 2005
  • This paper was studied on the damage behavior of stainless steel (STS 304) for gas boiler with specific resistance. The electrochemical polarization test of STS304 for gas boiler was carried out. And the anodic polarization and damage aspect, such as pitting corrosion, was considered. With being low specific resistance, the passive current density of STS 304 increases, passive region and pitting potential is low. Also, the patting aspect of STS304 In specific resistance 74Ωm water little appears, the pitting number increases and the damage behavior, such as pitting aspect, gradually grow bigger with being low specific resistance.

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Weld Quality Assurance Method using Statistical Analysis of Primary Dynamic Resistance During Resistance Spot Welding (1차 동저항 패턴의 통계적 분석에 의한 저항 점 용접의 용접 품질 예측에 관한 연구)

  • Jo, Yong-Jun;Lee, Se-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.10 s.181
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    • pp.2581-2588
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    • 2000
  • In previous studies, the dynamic resistance, which was calculated by the process variables measured at the electrode of the welding machine, and the electrode displacement were used for quality exa mination. However, in-process usage of such systems is not effective in systems that include a welding gun attached to a robot. In order to overcome such problems, we obtained and used the process variables from the welding machine timer. This would allow us to estimate real time in -process weld quality. For quality estimation, the features were extracted as factors from the primary dynamic resistance patterns, which were measured in t he welding machine timer. The relationship between the indexes and nugget size of the welds was observed through the regression analysis. Using the analyzed factors, a regression model that could estimate nugget diameter was developed. Two regression equations of the model were suggested depending on the factors, and it was showed that the model developed by stepwise method was effective one for weld quality estimation. The developed estimation model was in good linearity with the nugget diameter obtained through the experimentation.

Corrosion Behavior of Ti-Pd System Alloys by Microstructural changes (Ti-Pd계 합금의 미세조직변화에 따른 부식거동)

  • Cha, Sung-Soo;Kwak, Dong-Ju;Nam, Sang-Yong
    • Journal of Technologic Dentistry
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    • v.30 no.2
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    • pp.9-16
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    • 2008
  • The surface microstructural changes, mechanical properties and corrosion resistance of Ti-Pd alloys for dental biomaterials have been investigated. Ti, Ti-Pd alloys were melted in arc furnace and the corrosion resistance of Ti-Pd alloys was evaluated by anodic polarization test. The surface microstructural changes and mechanical properties of Ti-Pd alloys were analysed by scanning electron microscope and Vickers micro-hardness tester. The vickers hardnees of pure Ti improved by addition of Pd but Ti-25Pd alloy showed decreasing compared with Ti-15Pd. And anodic polarization and potentiostatic test were conducted in 5% HCl to quantify the resistance to corrosion with the addition of Pd, There was no significant difference in corrosion resistance between pure Ti, Ti-5Pd and Ti-15Pd alloy. However, Ti-25Pd alloy showed decreasing compared with pure Ti in corrosion resistance. From these results, it was concluded that newly formulated Ti-15Pd experimental alloy have adequate hardness and high corrosion resistance, and this alloy is promising candidate for a successful dental casting alloy.

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Corrosion Resistance of Degraded STS310S and STS347H by Cr-free Modified Si Organic/Inorganic Hybrid Coating Solution (Cr-free Si 변성 유/무기하이브리드 코팅액에 의한 열화된 STS310S 및 STS347H의 내식성)

  • Lee, So-Young;Kim, Young-Soo;Jeong, Hee-Rok;Kim, Gui-Shik;Nam, Ki-Woo
    • Journal of Power System Engineering
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    • v.19 no.6
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    • pp.12-18
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    • 2015
  • Austenitic stainless steels generally experience the occurrence of chromium-depleted zones at the boundaries, known as sensitization, caused by the carbide precipitation that takes place due to a welding process or heat treatment. Normally, the depleted zones become the focus of the intense corrosion. In this study, the Cr-free organic/inorganic hybrid solution was developed, and the artificially degraded STS316S and STS347H with the solution-coating investigated the corrosion resistance by salt spray test. Both the OIBD-1 and OIBD-2 solutions improved the corrosion resistance of STS310S and STS347H. The corrosion resistance with the OIBD-1 solution was better than that of OIBD-2 solution. Additionally, Both solutions have been proven excellence in adhesion ability, boiling water resistance and flexibility. However, a problem of rubbing after the boiling was found out to be overcome.

Study on the Physical Properties by Combining Epoxy and Acryl Electrodeposition Paints (에폭시와 아크릴 전착도료의 혼용성에 따른 물성 변화 연구)

  • Jung, Sung Soo;Yi, Dong Uk;Kim, Dong Won;Kim, Myung Hwan;Kwag, Sam Tag;Moon, Myung Jun
    • Journal of Surface Science and Engineering
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    • v.47 no.3
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    • pp.137-146
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    • 2014
  • The important drawback of epoxy electrodeposition(ED) coatings is the lack of the weathering resistance caused by the structure of bisphenol A. To improve this yellowing phenomena, acryl ED coatings have been developed. Compared with the epoxy ED coatings, however, acryl ED coatings are relatively weak in the corrosion resistance and mechanical properties. The purpose of this study is complemented their drawbacks by mixing epoxy and acryl ED paints. The salt spray, accelerated weathering test(QUV) and cupping, bending, impact test were employed to investigate the corrosion resistance, weathering resistance, and mechanical properties of ED coatings. When the ratio of acryl to epoxy resin of ED coating is 0.33, the weathering resistances are appropriately improved in condition maintaining the corrosion resistance. It was shown that the weathering resistance for epoxy ED coating was adjusted by optimally mixing acryl ED paint.

The Effect of the Additive Elements Alloying Method on the Corrosion Resistance of Sintered STS 316L (STS 316L 소결재료의 내식특성에 미치는 합금원소 첨가방법의 영향)

  • Kim, Hye Seong;Kim, Yoo Young;Park, Dong Kyu;Ahn, In Shup
    • Journal of Powder Materials
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    • v.20 no.3
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    • pp.203-209
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    • 2013
  • In this study, STS 316L powders with 3 wt.% Cu and 1 wt.% Sn known as corrosion-resistance reinforcement elements, are prepared to make different kinds of specimens, in which, 3 wt.% Cu and 1 wt.% Sn are added in different forms by mixing, alloying and fully alloying. After sintering in the same condition, the corrosion resistance, wear resistance and their mechanical properties of specimens are tested respectively. According to the comparison, STS 316L specimen sintered at 1270C showed the most excellent mechanical property: HRB 78 (hardness), 1130.7 MPa (RCS), 26.6% (Fraction Wear), It was similar with the specimen made of STS316L and fully alloyed Cu and Sn powders, meanwhile, the latter one appears the best corrosion resistance, 75hrs-salt immersion test results. In addition, the specimens with Cu and Sn powders additive showed relatively worse wear resistance in compared with STS316L specimen.

Effects of Thermal Contact Resistance on Film Growth Rate in a Horizontal MOCVD Reactor

  • Im Ik-Tae;Choi Nag Jung;Sugiyama Masakazu;Nakano Yoshiyaki;Shimogaki Yukihiro;Kim Byoung Ho;Kim Kwang-Sun
    • Journal of Mechanical Science and Technology
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    • v.19 no.6
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    • pp.1338-1346
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    • 2005
  • Effects of thermal contact resistance between heater and susceptor, susceptor and graphite board in a MOCVD reactor on temperature distribution and film growth rate were analyzed. One-dimensional thermal resistance model considering thermal contact resistance and heat transfer area was made up at first to find the temperature drop at the surface of graphite board. This one-dimensional model predicted the temperature drop of 18K at the board surface. Temperature distribution of a reactor wall from the three-dimensional computational fluid dynamics analysis including the gap at the wafer position showed the temperature drop of 20K. Film growth rates of InP and GaAs were predicted using computational fluid dynamics technique with chemical reaction model. Temperature distribution from the three-dimensional heat transfer calculation was used as a thermal boundary condition to the film growth rate simulations. Temperature drop due to the thermal contact resistance affected to the GaAs film growth a little but not to the InP film growth.