• Title, Summary, Keyword: surface tension

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Estimation of surface tension of liquid alloys under different oxygen partial pressure

  • Min, Sun-Gi;Lee, Jun-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.101-101
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    • 2008
  • The effect of oxygen partial pressure on the surface tension data of liquid alloys was investigated by means of comparing the calculated data and the measured one. Two binary alloy systems were chosen to observe the dependence of oxygen adsorption behavior on different oxygen partial pressures. It was found that the difference between the computed values and the experimental of the surface tension was within the range of maximum 10%.

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Wettability of Lubricant-Impregnated Electroplated Zinc Surface with Nanostructure (윤활유가 침지된 나노구조 전기아연도금층의 젖음성)

  • Jung, Haechang;Kim, Wang Ryeol;Jeong, Chanyoung;Lee, Junghoon
    • Journal of the Korean institute of surface engineering
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    • v.52 no.1
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    • pp.37-42
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    • 2019
  • Electrodeposited zinc layer is widely used as a sacrificial anode for a corrosion protection of steel. In this study, we modified the surface of electrodeposited zinc to have a hydrophobicity, which shows various advanced functionalities, such as anti-corrosion, anti-biofouling, anti-icing and self-cleaning, due to its repellency to liquids. Superhydrophobicity was realized on electrodeposited zinc layer with a hydrothermal treatment, creating nanostructures on the surface, and following Teflon coating. The superhydrophobic surface shows a great repellency to water with high surface tension, while liquid droplets with low surface tension easily adhered on the superhydrophobic surface. However, immiscible lubricant-impregnated superhydrophobic surface shows a great repellency to various liquids, regardless of their surface tension. Therefore, it is expected that the lubricant-impregnated surface can be an alternative of superhydrophobic surface, which have a drawback for some liquids with a low surface tension.

Preparation and Characterization of Surface Energy of BPDA-BAPP Polyimide

  • Kim, Kyung-Hoe;Kim, Yong-Gwon;Kwon, Young-Hwan
    • Macromolecular research
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    • v.17 no.6
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    • pp.388-396
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    • 2009
  • The surface properties (water sorption and repellency, adhesion) are closely related to the surface tension of polymer solids. The critical surface tension (${\gamma}_c$) and surface tension (${\gamma}_s$) of a polymer solid were estimated by the contact angle method by our quantitative imaging system. BPDA (3,3',4,4'-biphenyl tetracarboxylic dianhydride)-BAPP (1,3-Bis(4-aminophenoxy) propane) polyimide was successfully synthesized. The ${\gamma}_c$ values were analyzed by a Zisman plot, a Young-$Dupr\acute{e}$-Good-Girifalco plot, and a log ($1+cos{\theta}$) vs log ${\gamma}_L$ plot. The ${\gamma}_s$ value of BPDA-BAPE polyimide was evaluated using the geometric mean equation and our multiple regression analysis. The calculated values of ${{\gamma}_s^d$ (a dispersion component), ${{\gamma}_s^p$ (a polar component), ${{\gamma}_s^h$ (a hydrogen bonding component), and ${\gamma}_s$ were 30.79, 9.32, 0.20, and 40.31 $mN{\cdot}m^{-1}$, respectively. The ${\gamma}_s$ of BPDA-BAPP polyimide containing both a methylene group and an ether group was larger than that of the polyimide containing only a methylene group.

A Study on Elevated Temperature Fatigue Crack Growth Using Round Bar Specimen with a Surface Crack (표면균열을 갖는 원형봉재 시편을 이용한 고온 피로균열성장 연구)

  • So, Tae-Won;Yun, Gi-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.11
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    • pp.3415-3423
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    • 1996
  • The compact tension specimen geometry has been widely used for measuring fatigue crack growth rates at elevated temperature when the fatigue load is under tension/tension condition. However, most of the elevated temperature components which have significant crack growth life experience fatigue load under tension/compression conditions. Thus test techniques are required since the compact tension specimen cannot be used for tension/compression loading. In this paper, a simplified test procedure for measureing fatigue crack growth rates is proposed, which employs a round bar specimen with a small surface crack. Fatigue crack growth rates under tension/ tension loading conditions at elevated temperature were measured according to the proposed procedure and compared with those previously measured by C/(T) specimens. Since both the measured crack growth rates were comparable, the fatigue crack growth rates under tension/ compression load can be reliably measured by the proposed procedure. For monitoring crack depth. DC electric potential method is employed and an optimal probe location and current input conditions were proposed.

The Effect of the Surface Tension of Contaminants on Tracking Ageing of Polymeric Composites (오손액의 표면장력이 폴리머 복합재의 트래킹 열화에 미치는 영향)

  • 조한구;천종욱;이운용;한동희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.435-438
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    • 2002
  • In this paper, the effect of surface tension, wettability, flow rate of contaminants with varying surfactant content and frequency of applied voltage on the tracking breakdown of epoxy insulating materials were investigated. As the flow rate of contaminant is increased, the surface resistivity is decreased, and the leakage current is increased, the time to tracking breakdown is decreased. It is found that time to tracking breakdown depends on the surface tension of contaminant, that is difference of wettability And as the frequency of applied voltage is increased, time to tracking breakdown decreased.

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Effect of X-Irradiation in Vitro on the Pulmonary Surfactant in Rabbits (In Vitro X선조사(線照射)가 가토폐포표면(家兎肺胞表面) 활성물질(活性物質)에 미치는 영향(影響))

  • Cho, Joong-Hwan;Choo, Young-Eun
    • The Korean journal of physiology & pharmacology
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    • v.5 no.1
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    • pp.51-58
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    • 1971
  • In an attempt to further clarify the effect of X·irradiation on the activity of surfactant in rabbits, X-ray in dose of 900r was irradiated to the lung tissues of rabbits in vitro. Tension-area diagram of the lung extract was recorded automatically by a modified Langmuir-Wilhelmy balance with a synchronized recording system designed in this department. The surface tension of the lung extract was measured at 1,3,5,24 and 48 hours post-irradiation, and the results were compared with the non·irradiated normal group. The result$ thus obtained are summarized as follows: I The maximal surface tension, minimal surface tension, width of the tension·area diagram at the surface area of 40% in the lung extract and stability index of the normal rabbit long extract were 40.73 dynes/cm, 8.96 dynes/cm, 20.71 dynes/cm and 1.28, respectively. II. When 900r of X-ray was irradiated to the lung in vitro, 1) The maximal and minimal surface tensions did not differ noticeably from the normal at 1,3, and 5 post-irradiation hours, but the minimal surface tension increased significantly at 24 and 48 hours Post-irradiation. 2) The width of the tension area at the surface area of 40% showed a tendency of decrease throughout the experiment. 3) The stability index showed no significant change at 1,3 and 5 post-irradiation hours,but at 24 and 48 hours post-irradiation a significant decrease was observed comparing with the control. III. Activity of surfactant was significantly depressed by X·irradiation in vitro especially at 24 and 48 hours post-irradiation.

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The Surface Activities of Surfactant Mixtures (혼합 개면활성제의 개면활성에 관한 연구)

  • 정혜원
    • Journal of the Korean Society of Clothing and Textiles
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    • v.18 no.3
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    • pp.348-354
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    • 1994
  • The changes of surface activities in the aquaous solutions of mixed surfactants composed of linear sodium dodecylbenznesulfoate (LAS), polyoxyethylene nonyl phenylether (PE, EO=10) and polyethylene glycol monolauryl ether (LE, EO=25) have been studied. Addition of nonionic surfactants to LAS reduces the surface tension, especially at the lower concentration than cmc. The interfacial tension of olive oil/LAS was lower than the other surfactant solutions. The removal of triolein from cotton fabrics by nonionic surfactants and mixtures is higher than by LAS. The addition of NaCI to surfactant solutions even though reduces surface tension smaller but enthances oil removal more than that of $CaCl_2$.

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The Effects of Surface Shear Viscosity and Surface Tension on a Columnar Vortex Interacting with a Free Surface (자유표면과 반응하는 수직와류에 대한 표면점성계수와 표면장력의 영향)

  • Kim Kyung-Hoon;Sohn Kwon;Kim Seok-Woo
    • Journal of the Korean Society of Visualization
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    • v.3 no.1
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    • pp.51-57
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    • 2005
  • Vertices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed fur the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

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A Direct Calculation of Higher Heating Values of Ultrasonic Reformed Diesel Fuels by Using Their Viscosity and Surface Tension Measurements (초음파 개질 경유의 점도 및 표면장력 측정을 이용한 발열량 직접 계산)

  • Lee, B.O.;Ryu, J.I.
    • Journal of ILASS-Korea
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    • v.6 no.4
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    • pp.22-30
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    • 2001
  • The objective of this study is to develop the new equations for the calculation of higher heating values(HHVs) of reformed diesel fuels by ultrasonic treatment. Therefore, higher heating values of reformed diesel fuels by ultrasonic treatment are determined experimentally and calculated from their viscosity and surface tension measurements. The HHVs of the fuels are supposed to be a function of viscosity(Pa s) and surface tension(N/cm). The equations developed for the samples represent the correlation obtained by means of regression analysis. The HHVs calculated by developing new equations using viscosities showes the differences from the measured values ranging from -0.66 to 1.19 % and the correlation coefficient was -0.9411. The HHVs calculated by developing new equations using surface tensions showed the differences from the measured values ranging from -0.70 to 1.51 % and the correlation coefficient was 0.9999. The viscosity and the surface tension are characteristic properties of ultrasonic reformed diesel fuels for developing new formulae.

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Study on the Stokes' Flow within a Three-Dimensional Cavity Considering Surface Characteristics (액체의 표면 특성을 고려한 3차원 캐버티 내부의 스톡스 유동 특성 연구)

  • Heo, Hyo-Weon;Jung, Won-Hyuk;Suh, Yong-Kweon
    • 한국전산유체공학회:학술대회논문집
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    • pp.382-386
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    • 2011
  • In this study, a CFD code is developed to perform simulation of the surface and internal flow of a three-dimensional rectangular cavity driven by an external gas flow. Investigated in this study are surface characteristic such as surface tension, surface dilational viscosity(or surface elasticity), and surface viscosity. Visualization of the surface of water is performed to compare with the numerical results obtained with the developed in-house code. We have found that the surface flow is very sensitive to the surface tension and other configurations. The surface flow velocity obtained from the numerical solution is lower than the experimental result.

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