• 제목, 요약, 키워드: Surface Tension

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MEASUREMENT OF SURFACE TENSION OF MOLTEN METALS IN ARC WELDING

  • Shinobu Satonaka;Shigeo Akiyoshi;Inoue, Rin-taro;Kim, Kwang-Ryul
    • 대한용접접합학회:학술대회논문집
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    • pp.757-762
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    • 2002
  • Many reports have been shown that the buoyancy, electromagnetic force, surface tension, and gas shear stress are the driving forces of weld pool circulation in arc welding. Among them, the surface tension of molten metal plays an important role in the flow in weld pool, which are clarified by the specially designed experiments with small particles as well as the numerical simulations. The surface tension is also related to the penetration in arc welding. Therefore, a quantitative evaluation of surface tension is demanded for the development of materials and arc process control. However, there are few available data published on the surface tension of molten metals, since it depends on the temperature and the composition of materials. In this study, a new method was proposed for the evaluation of surface tension and its temperature dependence, in which it is evaluated by the equilibrium condition of acting forces under a given surface geometry, especially back surface. When this method was applied to the water pool and to the back surface of molten pool in the stationary gas tungsten arc welding of thin plate, following results were obtained. In the evaluation of surface tension of water, it was shown that the back surface geometry was very sensitive to the evaluation of surface tension and the evaluated value coincided with the surface tension of water. In the measurement of molten pool in the stationary gas tungsten arc welding, it was also shown that the comparison between the surface tension and temperature distribution across the back surface gave the temperature dependent surface tension. Applying this method to the mild steel and stainless steel plates, the surface tension with negative gradient for temperature is obtained. The evaluated values are well matched with ones in the published papers.

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Surface Tension of Magneto-Rheological Fluids

  • Rahimi, Shai;Weihs, Daniel
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.261-265
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    • 2016
  • Surface tension is a major factor in the thermodynamics as well as fluid properties of Magneto-Rheological Fluids (MRF). We measured the surface tension of an MRF using two different methods. A wettability characterization based on contact angles measurements for the fluid interacting with two different surfaces was conducted. A hydrocarbon based commercial MRF with more than 80% solid weight, placed on quartz and poly-tetra-fluoroethylene (PTFE) surfaces was used. We measured the fluids' surface tension value by means of contact angles measurements and by the falling drop method.

N-Dodecanoyl, N-Methyl Glucamine(GL 12)과 음이온 계면활성제 혼합물의 Dynamic Surface Tension에 관한 연구 (Studies on the Dynamic Surface Tension of GL12 and Anionic Mixtures)

  • 안호정;최규석
    • 공업화학
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    • v.7 no.1
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    • pp.101-108
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    • 1996
  • 본 연구에서는 수용액 내에서 생분해도가 우수하고 인체에 mild한 비이온성 계면활성제 GL12와 범용 음이온성 계면활성제인 linear laurylbenzene sulfonate(LAS) 또는 sodium polyoxyethylene(3) glycol lauryl ether sulfate(SLES) 각각 용액의 dynamic surface tension과 이들 계면활성제 혼합용액의 dynamic surface tension이 혼합비에 따라 어떻게 변화되는지 maximum bubble pressure method를 이용하여 조사하였다. 또한 salting-cut 효과가 있는 NaCl, CsCl과 salting-in 효과가 있는 요소를 계면활성제 용액에 첨가하여 이들 염들이 용액의 dynamic surface tension에 미치는 영향에 대하여도 연구하였다. 비이온성 계면활성제인 GL12의 dynamic surface tension은 염의 존재에 영향을 크게 받지 않았으나 음이온성인 SLES와 LAS는 크게 영향을 받았다. 또한 GL12/SLES와 GL12/LAS 혼합계에서도 GL12의 함량이 많을수륵 용액의 dynamic surface tension에 대한 염의 영향이 감소하였으나 LAS 또는 SLES의 함량이 증가할수록 염의 영향은 증가하였다.

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인장법에 의한 고점도 잉크의 표면장력 측정법 (The Elongation Method for the Measuring Surface Tension of High Viscosity Printing Ink)

  • 하영백;윤종태;구철회
    • 한국인쇄학회지
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    • v.21 no.2
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    • pp.89-100
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    • 2003
  • We have reviewed the method for surface tension of printing inks. Most of the methods fir for the low viscosity inks and solvents for inks. However, the inks for the offset lithography and intaglio should have high viscosity and high tack. The elongation of the ink filaments has more effect on the measuring surface tension than the energy of the surface molecules. In this paper, we propose the elongation method to estimate the surface tension of high viscosity printing inks. Even though we could measure the surface tension for low viscosity inks such as gravure and screen, elongation method could more useful to estimate the surface tension of lithography and intaglio inks than any other methods.

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혼합계면활성제 용액의 표면장력 성분 (The Surface Tension Components of Mixed Surfactant Solutions)

  • 정혜원;윤혜신
    • 한국의류학회지
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    • v.20 no.4
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    • pp.690-696
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    • 1996
  • In order to study the affect of surfactants on the soil removal, the dispersion and polar force components of surface tension for surfactant solutions (such as LAS, AS, AOS, AES, AE) were calculated using extended Fowkes equation. The contact angles on paraffin and surface tension of surfactant solutions were measured. Cmcs of LAS, AS, AES and AE were below the concentration of 0.05%, but the cmc of AOS was between 0.05% and 0.1%. The surface tension of AE was lowest but the dispersion force component was greastest. Total surface tension of every mixed anionic surfactant was lower than that of single surfactants, and the dispersion force components were almost decreased. The addition of sodium carbonate to the sufactant solutions decreased the surface tension, and the surface tensions of surfactant solutions were lowered after washing.

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다양한 산소분압에 따른 용융 Ag-Sn 및 Ag-Cu 합금의 표면장력 (Surface Tension of Molten Ag-Sn and Au-Cu Alloys at Different Oxygen Partial Pressures)

  • 민순기;이준호
    • 한국재료학회지
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    • v.19 no.1
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    • pp.13-17
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    • 2009
  • A semi-empirical method to estimate the surface tension of molten alloys at different oxygen partial pressures is suggested in this study. The surface tension of molten Ag-Sn and Ag-Cu alloys were calculated using the Butler equation with the surface tension value of pure substance at a given oxygen partial pressure. The oxygen partial pressure ranges were $2.86{\times}10^{-12}$$1.24{\times}10^{-9}$ Pa for the Ag-Sn system and $2.27{\times}10^{-11}$$5.68{\times}10^{-4}$ Pa for the Ag-Cu system. In this calculation, the interactions of the adsorbed oxygen with other metallic constituents were ignored. The calculated results of the Ag-Sn alloys were in reasonable accordance with the experimental data within a difference of 8%. For the Ag-Cu alloy system at a higher oxygen partial pressure, the surface tension initially decreased but showed a minimum at $X_{Ag}$ = 0.05 to increase as the silver content increased. This behavior appears to be related to the oxygen adsorption and the corresponding surface segregation of the constituent with a lower surface tension. Nevertheless, the calculated results of the Ag-Cu alloys with the present model were in good agreement with the experimental data within a difference of 10%.

$37^{\circ}C$에서 incubate 한 가토(家兎) 폐포표면활성물질(肺胞表面活性物質)의 활성도(活性度)의 변화(變化)와 in vitro X 선조사(線照射)의 영향(影響) (Changes of Activities of Rabbit Pulmonary Surfactant Incubated at $37^{\circ}C$, and effect of X-Irradiation in Vitro)

  • 김형규;주영은
    • The Korean journal of physiology & pharmacology
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    • v.5 no.2
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    • pp.63-70
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    • 1971
  • In an attempt to understand the possible effects of temperature and X-irradiation on the activities of surfactant in rabbits, the pulmonary surfactant from the rabbit was subjected to the incubation at $37^{\circ}C$ and X-irradiation with 900r in vitro, and activities of surfactant were measured at 10, 30, 60, and 90 minutes. Tension-area diagram of the lung extract was recorded automatically by the modified Langmuir-wilhelmy balance with a synchronized recording system designed in this Department. A comparison was made with the normal and the following results were obtained. 1) The maximal surface tension, minimal surface tension, width of the tension area diagram at the surface area of 40% and stability index of the normal rabbit lung extract were $31.6{\pm}3.11\;dynes/cm,\;8.2{\pm}0.56\;dynes/cm,\;21.4{\pm}4.40\;dynes/cm\;and\;1.12{\pm}0.22$,respectively. 2) In the $37^{\circ}C$ incubation group, maximal surface tension was similar to the normal value, while minimal surface tension was significantly lower and stability infer was markedly higher than the normal. 3) In the group where X-irradiation of 900r in vitro was applied, maximal surface tension did not differ greatly with the normal or the $37^{\circ}C$ incubation group. The minimal surface tension was significantly lower than the normal but comparing with the $37^{\circ}C$ incubation group, some decrease in minimal surface tension was noted. The width of the tension·area diagram at 40% and stability index in the irradiated group were significantly higher than the normal but a tendency of increase was noted comparing with the $37^{\circ}C$ incubation group.

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온도가 세척계의 표면장력에 미치는 영향(제1보) -세액의 표면장력 성분변화를 중심으로- (Effect of Temperature on the Surface Tensions in the Detergency System(I) -Change of Surface Tension Components of Washing Liquids-)

  • 채정희;김성련
    • 한국의류학회지
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    • v.17 no.4
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    • pp.511-517
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    • 1993
  • Changes of the surface and interface tension with temperature for washing liquids and alkanes were measured by FACE surface tensiometer. Using the extended Fowkes' equation, the dispersion and polar force components of the surface tension were estimated. The results were as follows : 1. The surface tensions of washing liquids and alkanes decreased almost linearly with the increase of temperature. 2. The interface tensions of 0.25% DBS/alkane increased slowly with the increase of temperature. In the case of nonionic surfactant solutions, however, the interface tensions with alkanes varied with the number of hydrophilic ethylene oxide(EO) groups. 3. Of the surface tension of water at $20^{\circ}C$, the dispersion force component was 25.3 dyn/cm and the polar force component was 47.8 dyn/cm. As the temperature increased, both the polar and dispersion force components decreased in a similar fashion. 4. The dispersion force component of surface tension of 0.25% DBS solution was 30.0 dyn/cm, and the polar force component was 2.2 dyn/cm at $20^{\circ}C$. The two components decreased with the increase of temperature. 5. As the temperature increased, the dispersion force component of surface tension decreased and the polar force component increased significantly for 0.25% NPPG-7.5EO solution. In the case of 025% NPPG-10EO, both the dispersion and polar force components decreased slowly, but the polar force component is expected to increase from $60^{\circ}C$. However, the polar force component of surface tension decreased with the increase of temperature for 025% NPPG-15EO solution, and at the temperature higher than $60^{\circ}C$ the surface tension is expected to be composed of only dispersion force component.

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GTA 용접에서 용융풀의 표면 변형이 유동과 진동에 미치는 영향 (Effects of Surface Depression on Pool Convection and Oscillation in GTAW)

  • 고성훈;최상균;유중돈
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.70-77
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    • 1999
  • Surface depression in the arc welding is calculated numerically to analyze its influence on pool convection and oscillation. The magnitude of surface depression due to arc pressure on the stationary GTA pool surface is relatively small, and fluctuations of the surface and velocity are caused mainly by arc pressure. The inward flow on the surface due to the electromagnetic force and positive surface tension gradient acts to decrease surface depression. Surface depression appears to have minor effects on average flow velocity and thus pool geometry. Pool oscillation occurs due to surface vibration, and oscillation frequencies are affected mainly by the surface tension and pool width. The input parameters such as arc pressure and current have negligible effects on the oscillation frequency, and the surface tension gradient has limited effects. Since the oscillation frequency varies slightly according to penetration, pool oscillation for the partial penetration weld pool is applicable to monitor the pool width.

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건축 인장구조시스템의 분류와 구성유형 (The Type of Composition and Classification of Tension Structure Systems in Architecture)

  • 이주나;박선우;박찬수
    • 한국공간구조학회논문집
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    • v.3 no.3
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    • pp.111-120
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    • 2003
  • Tension members is a type of effective structural member, which is often used in large span structures. The structure systems composed with tension members are combined in various way and specific formations. So, there are need to research into the formations of tension structure and the type of adaptation in tension structure architectures. The structure systems with tension members were considered as tension main system, vector system and tension supported bending system, comprehensively. And tension structures were classified into the formation of tension structure with uniaxial or multiaxial line tension member, with surface member, with hybrid member of line and surface, concerning the flow of tension force. In each the formation of tension structure, the typical adaptations to architecture were also investigated through architecture examples. The type of the formation can be used to plan an architecture with respect to the flow of tension force and structural feature.

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