• Title/Summary/Keyword: sessile drop method

Search Result 30, Processing Time 0.028 seconds

Sessile Drop의 형상으로부터 수치계산에 의한 표면장력 측정 (A Numerical Method for Determining Surface Tension of Sessile Drop)

  • 정영수
    • 한국세라믹학회지
    • /
    • 제33권12호
    • /
    • pp.1325-1330
    • /
    • 1996
  • Sessile drop method에 의해서 표면장력을 간단히 구하는 수치계산법을 계산프로그램과 같이 소개하였다. 이방법에 의하면 표명장력의 계산에 필요한 data는 sessile drop 표면상의 임의의 한 점에서의 좌표(X.Z)와 그 점에서의 접선의 각도${\theta}$, 그리고 밀도${\rho}$가 전부이다. 따라서 sessile drop의 형상으로부터 가장 정밀한 측정이 가능한 임의의점을 선정하여 그 점의 좌표, 접선의 각도를 측정하면 되므로 종래의 방법보다 정확한 값을 얻을 수 있다. 또한 4개의 data를 입력하는 것만으로 계산결과가 단시간에 나오므로 계산과정이 대단히 간단하다. Sessile drop의 크기, 접선의 각도, 밀도 등에 제한이 없으므로 응용범위가 넓다. 하나의 sessile drop에서 수개의 점으로부터 구한 각 표면장력의 값을 상호 비교하면 측정치 및 계산결과에 대하여 신뢰성을 높일 수 있다. 또한 이 수치계산법을 응용하면 pendant drop method에의 응용, 그외 sessile drop의 체적, 표면적, 접촉각의 계산 등에도 이용할 수 있다.

  • PDF

롤투롤 시스템에서 플렉시블 소재에 인가된 장력과 분사 높이가 액적 접촉각에 미치는 영향 (The Effect of Tension and Drop Height on Contact Angle of Droplet on Flexible Substrate in Roll-to-Roll Systems)

  • 김동국;이창우
    • 한국정밀공학회지
    • /
    • 제34권3호
    • /
    • pp.167-172
    • /
    • 2017
  • This study proposes a method for identifying correlations between tension and drop height for sessile droplets in a roll-to-roll processing system. The effect of tension and drop height on the contact angle of a sessile droplet is presented. Design of experiment (DOE) methodology and statistical analysis are used to define a correlation between the process parameters. The contact angle is decreased while increasing tension and drop height. The influence of the tension is less significant on the contact angle compared with the effect of the drop height. However, tension should be considered as a major parameter because it is not easy to fix with roll eccentricity and compensating speed of the driven roll. The results of this study show that the effect of tension on the contact angle of a sessile droplet is more important than drop height because the drop height is fixed when the process systems are determined.

Wetting properties between silver-copper-titanium braze alloy and hexagonal boron nitride

  • Sechi, Yoshihisa;Matsumoto, Taihei;Nakata, Kazuhiro
    • 대한용접접합학회:학술대회논문집
    • /
    • 대한용접접합학회 2009년 추계학술발표대회
    • /
    • pp.205-209
    • /
    • 2009
  • Wetting properties between silver-copper-titanium braze alloys with different titanium contents up to 2.8 mass% and hexagonal boron nitride ceramics were investigated using sessile drop method at 1123K in Argon. The final contact angle is less than $30^{\circ}$ when the Ti content was over 0.41 mass%. Meanwhile, the contact angle curves show different behavior. In case of using braze alloy containing 2.8 mass% of titanium, the initial contact angle is acute angle just after the melting of braze. In case of brazes containing titanium less than 2.26 mass%, the contact angle is larger than $90^{\circ}$ at the beginning and slowly decreases to acute angle. The reaction layer of titanium nitride is observed at the interface. In addition, the reaction of Ti in the braze and N in the bulk h-BN seemed to show diffusion limited spreading.

  • PDF

알루미나의 순도에 따른 알루미나와 실리케이트계 유리와의 젖음성에 관한 연구 (A Study on Wettability of Silicate Glasses on the Different Impurities in Alumina Substrates)

  • 안병국
    • Journal of Welding and Joining
    • /
    • 제16권2호
    • /
    • pp.122-128
    • /
    • 1998
  • This investigation was performed to collect fundamental informations concerning the behavior of glass solders on ceramic joining process. The wettability of glasses on two types of alumina was evaluated by sessile drop method. SiO$_2$-CaO-Al$_2$O$_3$system glasses were selected as solder glasses, and alumina that have different purities were used for substrate materials. It is indicated that contact angles of glasses on 99% purity of alumina substrate do not change as increasing time at elevated temperature, however the contact angles on the 92% purity of alumina substrate exhibit the strong time dependency. The time-dependent property on 92% alumina was due to the interlayer reactions occurred between the glass solder and impurities on the substrate.

  • PDF

질화규소와 실리케이트계 유리의 젖음성에 관한 연구 (A Study fur Wettability of Silicate Glasses on Silicon Nitride)

  • 안병국
    • Journal of Welding and Joining
    • /
    • 제20권3호
    • /
    • pp.116-121
    • /
    • 2002
  • For the accumulation of a fundamental knowledge about the behavior of glass solder during the joining of ceramics, the wettability of solder on silicon nitride have been measured by sessile drop method. $SiO_2-MgO-Al_2O_3$ g1ass solder and oxynitride glass solders were selected as examples while silicon nitride which were used as substrates. Contact angle of solder on silicon nitride didn't decrease with time at high nitrogen content in the solder, but low nitrogen content in solders have the time-dependent property. Reason which contact angle of low nitrogen content in solders decrease on silicon nitride was that diffusion of nitrogen take place between solder and silicon nitride.

Anisotropy of Wetting of Molten Fe on α-Al2O3 Single Crystal

  • Cho, Seung-Youn;Lee, Joon-Ho
    • 한국재료학회지
    • /
    • 제18권1호
    • /
    • pp.18-21
    • /
    • 2008
  • The wetting behavior of molten Fe on ${\alpha}-Al_2O_3$ single crystals with three different crystallographic orientations, $R(01\bar{1}2),\;A(11\bar{2}0),\;and\;C(0001)$, was investigated using the sessile drop method under a 10%$H_2-Ar$ atmosphere at 1873 K. It was found that the differences in the contact angle of the three differently oriented ${\alpha}-Al_2O_3$ single crystals were not significant (within $5^{\circ}$, which corresponded to the changes in the work of adhesion of $157mJ/m^2$) due to the surface reconstruction.

Effect of Al and Mg Contents on Wettability and Reactivity of Molten Zn-Al-Mg Alloys on Steel Sheets Covered with MnO and SiO2 Layers

  • Huh, Joo-Youl;Hwang, Min-Je;Shim, Seung-Woo;Kim, Tae-Chul;Kim, Jong-Sang
    • Metals and materials international
    • /
    • 제24권6호
    • /
    • pp.1241-1248
    • /
    • 2018
  • The reactive wetting behaviors of molten Zn-Al-Mg alloys on MnO- and amorphous (a-) $SiO_2$-covered steel sheets were investigated by the sessile drop method, as a function of the Al and Mg contents in the alloys. The sessile drop tests were carried out at $460^{\circ}C$ and the variation in the contact angles (${\theta}_c$) of alloys containing 0.2-2.5 wt% Al and 0-3.0 wt% Mg was monitored for 20 s. For all the alloys, the MnO-covered steel substrate exhibited reactive wetting whereas the $a-SiO_2$-covered steel exhibited nonreactive, nonwetting (${\theta}_c>90^{\circ}$) behavior. The MnO layer was rapidly removed by Al and Mg contained in the alloys. The wetting of the MnO-covered steel sheet significantly improved upon increasing the Mg content but decreased upon increasing the Al content, indicating that the surface tension of the alloy droplet is the main factor controlling its wettability. Although the reactions of Al and Mg in molten alloys with the $a-SiO_2$ layer were found to be sluggish, the wettability of Zn-Al-Mg alloys on the $a-SiO_2$ layer improved upon increasing the Al and Mg contents. These results suggest that the wetting of advanced high-strength steel sheets, the surface oxide layer of which consists of a mixture of MnO and $SiO_2$, with Zn-Al-Mg alloys could be most effectively improved by increasing the Mg content of the alloys.

Wetting Behavior of Dolomite Substrate by Liquid Fe-19%Cr-10%Ni Alloy at 1753K

  • Shin, Min-Soo;Lee, Joon-Ho;Park, Joo-Hyun
    • 한국재료학회지
    • /
    • 제19권2호
    • /
    • pp.115-118
    • /
    • 2009
  • The use of dolomite refractories has increased during the past several years in the manufacturing of clean steel during the stainless steelmaking process. However, at the same time, the use of dolomite refractories has led to what is known as the skull formation. In the present work, to understand the skull formation, the wetting characteristics of dolomite substrates by liquid Fe-19wt%Cr-10wt%Ni alloys in various oxygen partial pressures were initially investigated at 1753K using the sessile drop technique. For comparison, the wetting characteristics of alumina substrates were investigated with the same technique. It was found that the wetting index, (1+$cos{\theta}$), of dolomite is approximately 40% higher compared to those of alumina. In addition, the oxygen partial pressure to generate the surface oxide, which may capture the liquid metal on the refractory surface, for dolomite is much lower than that for alumina. From this study, it was concluded that the use of dolomite is much more closely associated with the skull formation compared to the use of alumina due to the stronger wettability and the surface oxide formation at a lower oxygen partial pressure of dolomite.

표면 처리 방법에 따른 타이타늄의 미세 표면 거칠기, 표면 젖음성, fibronectin 흡착량에 미치는 영향 (EFFECTS OF VARIOUS SURFACE TREATMENTS FOR TITANIUM ON SURFACE MICRO ROUGHNESS, STATIC WETTABILITY, FIBRONECTIN ADSORPTION)

  • 신화섭;김영수;신상완
    • 대한치과보철학회지
    • /
    • 제44권4호
    • /
    • pp.443-454
    • /
    • 2006
  • Purpose: This study aims to get the fundamental data which is necessary to the development direction of implant surface treatment hereafter, based on the understanding the surface structure and properties of titanium which is suitable for the absorption of initial tissue fluid by researching effects of additional surface treatments fir sandblasted with large git and acid-etched(SLA) titanium on surface micro-roughness, static wettability, fibronectin adsorption Materials and Method: In the Control groups, the commercial pure titanium disks which is 10mm in diameter and 2mm in thickness were treated with HCI after sandblasting with 50$\mu$m $Al_2O_3$. The experiment groups were made an experiment each by being treated with 1) 22.5% nitric acid according to SLA+ASTM F86 protocol, 2) SLA+30% peroxide, 3) SLA+NaOH, 4) SLA+ Oxalic acid, and 5) SLA+600$^{\circ}C$ heating. In each group, the value of Ra and RMS which are the gauges of surface roughness was measured, surface wettability was measured by analyzing with Sessile drop method, and fibronectin adsorption was measured with immunological assay. The significance of each group was verified by (SPSS, ver.10.0 SPSS Inc.) Kruskal-Wallis Test. (α=0.05) And the correlation significance between Surface micro-roughness and surface wettability. surface roughness and fibronectin adsorption, and surface wettability and fibronectin adsorption was tested by Spearman's correlation analysis. Result: All measure groups showed the significant differences in surface micro-roughness, surface wettability, and fibronectin adsorption. (p<0.05) There was no significance in correlation among the surface micro-roughness, surface wettability, and fibronectin adsorption. (p>0.05) Conclusion: Surface micro-roughness and surface wettability rarely affected the absorption of initial tissue fluid on the surface of titanium.