Showing papers on "Sessile drop technique published in 1988"
TL;DR: In this paper, the wettability of Al2O3 single crystals by aluminium is investigated in the 933-1273 K temperature range by the sessile drop method under a low total pressure (4 × 10−5Pa) and an oxygen partial pressure of about 10−15 Pa.
249 citations
TL;DR: In this article, the Gibbs-Langmuir law was applied to the sessile drop technique on the surface of a sapphire at a temperature range of 927-2077°C and the surface energy was determined to be γlv = 1.757-3.3 x 10-4T(°C) J/m2.
Abstract: The wetting behavior of liquid copper on sapphire is affected by the crystallographic orientation of the sapphire surface, the oxygen partial pressure, and the temperature. The influences of each of these conditions have been studied by the sessile drop technique over the oxygen partial pressure range 10-2-10-20 atm at temperatures of 1100 and 1250°C. The effect of oxygen partial pressure on the liquid copper surface energy follows the Gibbs-Langmuir law. The contact angle varies with the crystallographic orientation of the sapphire surface. This variation is more significant at higher oxygen partial pressures, but is eliminated at higher temperatures. The liquid copper surface energy was determined to be γlv = 1.757-3.3 x 10-4T(°C) J/m2. The solid surface energy of sapphire was estimated as γsv = 1.961-4.7x 10-4T(°C) J/m2, which applies only to the temperature range 927-2077°C.
83 citations
TL;DR: In this paper, a chemical system where interfacial reactions and oxide film effects could be isolated was used to evaluate the wetting of ceramic surfaces by aluminum alloys, and the system Al-Mg-O was chosen since it is technologically important and high-purity, well-characterized materials are readily available.
Abstract: The wetting of ceramic surfaces by aluminum alloys has been reexamined using a chemical system where interfacial reactions and oxide film effects could be isolated. The system Al–Mg–O was chosen since it is technologically important and high-purity, well-characterized materials are readily available. Magnesium alloyed with the aluminum sessile drop and silicon picked up from the experimental apparatus cause an initial reduction in contact angle by altering the protective nature of the oxide film formed on the sessile drop. Evidence of spreading is observed as an intermediate process in the reactive sessile drop pairs. Reaction products formed between the Al–Mg alloys and sapphire (Al2O3), spinel (MgAl2O4), or periclase (MgO) can be interpreted with predicted phase equilibria and the measured loss of magnesium from the sessile drop. Only the rate of the periclase alloy interaction was rapid enough to result in a continuous product layer after 24 h at 800 °C. The volatilization of all of the magnesium from the sessile drop resulted in the formation of a true Al–Al2O3 interface. The contact angle for a true Al–Al2O3 interface is 88 ± 5 deg at 800 °C. The liquid-solid interfacial energy is 1688 ergs/cm2.
55 citations
02 May 1988-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, a study was made on the wettability, structure, and chemical states of ion implanted silicone rubbers at room temperature at energies of 50 and 100 keV.
Abstract: A study has been made on the wettability, structure, and chemical states of ion implanted silicone rubbers. C + , N 2 + , O 2 + , and Ar + ion implantations were performed at energies of 50 and 100 keV at room temperature. The fluences ranged from 10 12 to 10 17 ions/cm 2 . Ion implantation caused the surface roughness to increase 2–3 times. Wettability was estimated by means of the sessile drop method using water, of which the results showed that the contact angle of water decreased from 98.9° to 48° as the fluence increased. The results of XPS measurements showed that implanted elements formed a Gaussian-like distribution, host elements were redistributed and no change in binding energies of O 1s , C 1s and Si 2p occurred. Results of FT-IR-ATR showed that ion implantation broke up original chemical bonds to form new radicals, the amounts of which are related to the fluences. It is concluded that the change in wettability may be caused by formation of new radicals rather than roughening of the surface under ion implantation.
43 citations
TL;DR: In this article, the line tension of the three-phase contact zone of a sessile drop was determined experimentally using the modified Young equation and a linearized form of the Young equation.
43 citations
TL;DR: The surface tension and wetting characteristics of four commercial Ni-based alloys (UD718, Waspaloy, UD720, and UD520), pure Ni, and three special alloys as discussed by the authors on various ceramic substrates (including alumina, zirconia, hafnia, and yttria) were investigated using sessile drop experiments.
Abstract: The surface tension and wetting characteristics of four commercial Ni-based alloys (UD718, Waspaloy, UD720, and UD520), pure Ni, and three special alloys (Ni-20 percent Cr, Ni-20 percent Cr-1 percent Al, and Ni-20 percent Cr-4 percent Al) on various ceramic substrates (including alumina, zirconia, hafnia, and yttria) were investigated using sessile drop experiments. Most of the systems studied exhibited a nonwetting behavior. Wetting improved with holding time at a given temperature to the point that some systems, such as Ni-20Cr on alumina, Ni-20Cr-4Al on alumina and on yttria, became marginally wetting. Wetting characteristics were apparently related to constitutional undercooling, which in turn could be affected by the metal dissolving some of the substrate during measurements.
40 citations
TL;DR: The surface tension of liquid tin has been measured at 560 K by the sessile drop method, as a function of the oxygen surface content measured on the liquid surface by AES.
28 citations
TL;DR: In this paper, the work of adhesion of an alloy against ZrO2 was evaluated from the equilibrium contact angle of the alloy using a sessile drop technique at 1373 K under a vacuum.
Abstract: The contact angles of molten Al-Cu alloys on CaO-stabilized ZrO2 have been measured using a sessile drop technique at 1373 K under a vacuum. The work of adhesion, Wad, of an alloy against ZrO2 was evaluated from the equilibrium contact angle of the alloy. The Wad values Al-Cu alloys with copper contents up to 10 at% are the same or slightly higher than the value of 1.25 J m−2 for pure aluminium. On further increase in copper content, Wad gradually decreases to 0.8 J m−2 for pure copper at 1373 K. The general trend in the work of adhesion against copper content of Al-Cu alloys is in accordance with the copper-content dependence of the joining strength of ZrO2 joints brazed with the Al-Cu alloys. A ZrO2 joint brazed with Al-1.7 at% Cu filler provides the maximum fracture strength of 105 MPa at room temperature, and this improved strength of ZrO2 is maintained at elevated temperatures up to 773 K. The joining strength of a ZrO2 joint brazed with an Al-Cu alloy is dominated by the mechanical properties of the alloy in addition to the wettability of the alloy against ZrO2.
25 citations
TL;DR: In this article, a modified sessile drop technique is described and its use is defended as having a sound basis in surface chemical theory, which suggests the existence of a measurable surface property related to the previously unmeasurable polar component of contact surface energy.
20 citations
01 Sep 1988-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the wettability of six different types of hot-pressed silicon nitride by liquid copper was evaluated at a temperature of 1373 K by the sessile drop method.
Abstract: The wettability of six different types of hot-pressed silicon nitride by liquid copper was evaluated at a temperature of 1373 K by the sessile drop method. The selected materials were such as to cover a wide range of additives (Y2O3, MgO, ZrO2 and Al2O3) and hot-pressing conditions. The experimental results were related to the microstructures of the substrates, and the equilibrium contact angle values were correlated with the physicochemical characteristics of the materials and with the mechanical status of their surfaces. A mean contact angle value of 135° was found for five out of the six types, leading to a value of 380 mJ m−2 for the work of adhesion. The sixth type exhibited a contact angle value of 144° and a value of 250 mJ m−2 for the work of adhesion. The different results obtained for the various types of substrate were ascribed to the effects induced by the roughness of the substrates, whereas the different ways of producing the materials and the oxide content did not markedly affect the materials' wettability.
15 citations
Patent•
17 Mar 1988
TL;DR: In this paper, a method for measuring surface tension is proposed based on the determination of the wetting angle on a drop (3) which is formed by wetting a solid, and a video image of the drop is first generated and the brightness values of the appertaining image pixels are digitilized and stored in a computer (6).
Abstract: The method for measuring surface tension is based on the determination of the wetting angle on a drop (3) which is formed by wetting a solid. For the determination of the wetting angle, a video image of the drop (3) is first generated and the brightness values of the appertaining image pixels are digitilized and stored in a computer (6). The computer (6) then determines the contour of the drop (3) in the vicinity of the three-phase point where liquid, solid surface and atmosphere meet one another. This contour is then approximated analytically by a polynomial and the wetting angle subsequently determined by means of formation of the first derivative of the polynomial at the position of the three-phase point. The appertaining measured value is further processed directly by the computer (6), in order to determine the desired surface tension of a liquid or a solid having polar and non-polar components.
01 Jun 1988
TL;DR: In this paper, a dynamique d'etalignement vers l'equilibre, ont ete etudies pour le cas d'une goutte posee sur un solide mince.
Abstract: L'etat final d'equilibre, ainsi que la dynamique d'etalement vers l'equilibre, ont ete etudies pour le cas d'une goutte posee sur un solide mince
TL;DR: In this article, a laser beam was aimed at the solid-liquid-air interface of a sessile drop on a contact lens, producing two lines of diffraction which are theoretically normal to the profile of the fluid and solid surfaces at the point of contact.
Abstract: A laser beam, aimed at the solid-liquid-air interface of a sessile drop on a contact lens, produces two lines of diffraction which are theoretically normal to the profile of the fluid and solid surfaces at the point of contact. In the present experiments, the beam and the diffraction patterns were projected on a flat screen perpendicular to the beam, and the angle was measured as a contact angle. The angle was measured on curved surfaces (contact lenses) of 6.5 to 8.9 mm radius and for each material studied, the angle: (1) was independent of the front surface radius, (2) was independent of droplet volume at 2 and 10 microliter, and (3) decreased with time after drop placement. The laser-derived measurements correlated well with contact angles measured by goniometry on contact lenses and a variety of other materials (r = 0.86; p less than 0.0001). Because the diffraction lines are straight and are generated at the point of contact, the angle formed by them is measured easily with a protractor, yielding a convenient and reproducible contact angle measurement. An application of the method was demonstrated by measuring contact angles for saline-containing 0 to 2% bovine serum albumin or bovine submaxillary mucin on Silafocon-A (Polycon II), Pasifocon C (Paragon EW), and polymethyl methacrylate (generic PMMA and Paragon 18) lenses. On each material, physiological concentrations of mucin, but not of albumin, significantly (p greater than 0.01) decreased contact angles by 8 to 15 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal Article•
TL;DR: In this paper, the density, surface tension, wettability and adhesive power of liquid high purity, technical pure Al (99.999 wt), Al-RE alloy on BN plate were measured using sessile drop method.
Abstract: The density, surface tension, wettability and adhesive power of liquid high purity
Al (99.999 wt-%), technical pure Al (99.6 wt-%) and Al-RE alloy on BN plate were measured
using sessile drop method. The results show that both the density and surface tension gradually
decrease but the adhesive power and wettability gradually increase with increasing temperature.
The density increases and the shaface tension, wettability as well as adhesive power decrease
with the increase of RE content respectively.
TL;DR: In this article, the work of adhesion and the interfacial energies of polycrystalline Al2O3 and the liquid metals Bi, Pb, Cu and Ni in argon-atmosphere were investigated.
Abstract: Mit Hilfe von Benetzungsexperimenten wurde der Gleichgewichtswinkel θ fur die Kombinationen festes polykristallines Al2O3 in Kontakt mit den geschmolzenen Metallen Bi, Pb, Cu und Ni in Argonatmosphare bestimmt. Es zeigte sich, das die geschmolzenen Metalle, an ihren Schmelzpunkten, das Al2O3 nicht benetzen (θ > 90°). Durch Hinzunahme von Literaturdaten wurde die Adhasionsarbeit und die Grenzflachenenergie in den untersuchten Systemen ermittelt. Beide Grosen andern sich linear mit der Temperatur. Die Temperaturkoeffizienten sind errechnet worden. Fur die geschmolzenen Metalle Cu und Ni kann der nichtbenetzende Zustand bei Temperaturen, die noch unterhalb der Schmelztemperatur des Al2O3 liegen, in einen teilbenetzenden (θ <90°) ubergehen.
Wetting Angles and Interfacial Energies of the Liquid Metals Bi, Pb, Cu and Ni in Contact with Solid Al2O3
Sessile drop experiments were used to determine the wetting angle (θ) between polycrystalline Al2O3 and the liquid metals Bi, Pb, Cu and Ni in argon-atmosphere. It was found that at their melting points the liquid metals do not wet the Al2O3 (θ > 90°). Using available literature data the work of adhesion and the interfacial energies in the investigated systems were calculated. Both show a linear dependence with temperature. The temperature coefficients were calculated. In the case of Cu and Ni the wetting behaviour is improved (θ < 90°) at higher temperature below the melting point of Al2O3.
TL;DR: The results suggest that goniometry on contact lens surfaces, for the most part, is uninfluenced by lens parameters and environmental conditions.
Abstract: The present investigation was designed to determine the effect of lens parameters and lens environment on measurements of contact angle. The sessile drop contact angle of saline on four rigid [polymethyl methacrylate (PMMA) and silicone/acrylate] contact lens materials was examined with a Rame-Hart goniometer to determine how front surface radius, drop size, time after drop placement, humidity, and desiccation affect measurements of lens wettability in vitro. Contact angles of Silafocon A and PMMA were relatively uninfluenced by front surface radii between 7.7 and 8.85 and 7.3 to 8.8 mm, respectively. Contact angles of Pasifocon C and modified PMMA were slightly but significantly influenced by front surface radii between 6.4 and 7.5 mm. For drop volumes from 2 to 20 microliter, all materials yielded contact angles, which were unaffected by drop size. The contact angle of lenses stored in the hydrated or dehydrated state was not affected by chamber humidity between 31 and 76%. In the ranges tested, drop size, humidity, and hydration had no significant effect on the contact angle within 1 to 6 min after drop placement. In addition, surface scratches had no effect on lens wettability. The results suggest that goniometry on contact lens surfaces, for the most part, is uninfluenced by lens parameters and environmental conditions.
TL;DR: In this article, the sessile drop method was used to measure the wettability of graphite by the molten Al-Li alloy, and the relationship between the thickness of reaction layer at the interface and the wetability was discussed.
Abstract: The wettability of graphite by the molten Al-Li alloy was measured using the sessile drop method, and the relationship between the thickness of reaction layer at the interface and the wettability was discussed. The contact angle of the molten aluminum on the graphite decreased with the increase in temperature, and the thickness of reaction layer increased with the rise in temperature. The wettability of graphite by the molten aluminum was considerably improved by the addition of lithium in aluminum. The addition of lithium suppressed the formation of reaction layer. The contact angle of the molten aluminum on the graphite in He-H2 atmosphere was larger than that under reduced pressure.
TL;DR: The height of a sessile drop of liquid when placed on a smooth solid surface increases as the drop volume increases, until it reaches a limiting value for a very large drop.
Abstract: The height of a sessile drop of liquid when placed on a smooth solid surface increases as the drop volume increases, until it reaches a limiting value for a very large drop. The magnitude of the height and the contact angle depends on the different physical properties of the system. A large value for the contact angle is often associated with a large value for height and vice versa.
TL;DR: In this article, a sessile-drop method was used to wet an Al2O3 substrate by liquid gold in an atmosphere of argon, and an empirical relation was established between the contact angle and the temperature or surface tension of the liquid drop by the use of the diameter and the height of the Sessile drop.
Abstract: The wetting of an Al2O3 substrate by liquid gold was investigated by means of the sessile-drop method in an atmosphere of argon. An empirical relation was estabilished between the contact angle and the temperature or surface tension of the liquid drop by the use of the diameter and the height of the sessile drop. The contact angle was constant with time, but decreased linearly with an increase in temperature. The variation in the contact angle with temperature is correlated with the surface tension of the sessile drop. The surface tension of liquid gold was obtained as 933 dyn cm−1 at 1080 °C and 917 dyn cm−1 at 1100 °C and the temperature coefficient of the surface tension of liquid could be estimated to be −0.80 dyn cm−1 °C−1. The critical surface tension (γc) and the surface tension of liquid gold at 0 K of Al2O3 (γLV°) were 20 and 2015 dyn cm−1, respectively.
TL;DR: In this paper, the surface tension of liquid Co-S, Co-C and CoC-S alloys is determined at 1550°C by the sessile drop method.
Abstract: The surface tension (y) of liquid Co-S, Co-C and Co-C-S alloys is determined at 1550°C by the sessile drop method. The distribution of sulfur in different depths from the surface of a Co-S alloy and the change of surface concentration of sulfur with the increase of temperature are measured by Auger Electron Spectroscopy(AES). The data obtained by the sessile drop method are dealt with by a computer program. The surfaceactivities of elements and the distribution of surface-active elements in the surface layer of liquid alloys are also discussed here.
TL;DR: Nguyen et al. as discussed by the authors examined the effects of surface active agents on contact angle hysteresis by photographing sessile drops at the point of incipient motion on an inclined solid.
01 Jan 1988
TL;DR: In this paper, the authors measured the surface/interfacial and adsorption properties, particle size, and specific surface area of Lignite (35-, 200-, and 400-mesh), Graphite Powder, Kaolin, and Pyrite, using the Omnicon Alpha Particle Field Image Analyzer.
Abstract: This project consists of four major experiments, in which the surface/interfacial and adsorption properties, particle size, and specific surface area of Lignite (35-, 200-, and 400-mesh), Graphite Powder, Kaolin, and Pyrite, are measured. The first two experiments involve measuring the external specific surface area of the six powdered samples using the BET volumetric adsorption apparatus with N/sub 2/ as the adsorbate, and measuring five average characteristic particle diameters and the particle size distribution of these samples with the Omnicon Alpha Particle Field Image Analyzer. The third experiment involves obtaining the adsorption and desorption isotherms of the samples and determining the effect of pressure, temperature, particle size, and intrinsic nature of the coal mineral on these isotherms. Finally, the fourth experiment consists of two parts: (1) The pendant drop method, involving a water pendant drop in the presence of a CO/sub 2/(g) or CO/sub 2/(1) medium, in which the liquid-vapor and liquid-liquid interfacial tensions are measured as functions of CO/sub 2/ pressure, temperature, and CO/sub 2/ phase used, based on the drop's physical dimensions at equilibrium; (2) the sessile drop method, involving a water sessile drop in equilibrium on a pelletized sample of the coal mineral in a CO/sub 2/(g) ormore » CO/sub 2/(1) environment. The ultimate objective of this project is to determine the effect of the system parameters (i.e. CO/sub 2/ pressure, temperature, CO/sub 2/ phase) and nature of the coal minerals (i.e. intrinsic and particle size/surface area) on the relative wettability of the three-phase system of coal mineral-water-CO/sub 2/ through an analysis of the interfacial and adsorption properties of the coal minerals.« less
01 May 1988
TL;DR: The use of the dynamic version of the Whilhelmy plate device, in which the liquid phases are in motion relative to a solid phase, has been used in several surface chemistry studies as mentioned in this paper.
Abstract: The preferential wetting characteristics of rock/crude oil/water systems play an important role in determining the location, flow and distribution of fluids in reservoirs. The importance of wetting preference in oil reservoirs has been reviewed. Contact angle measurements are one method of obtaining quantitative wettability values and are usually measured in the petroleum industry by the sessile drop method or a modification of this technique. However, the sessile drop method is limited for several reasons. The tests are usually conducted on pure mineral surfaces, unlike the heterogeneous rock surfaces in reservoirs, and can be be very difficult as well as time consuming. The Wilhelmy hanging plate method has been used for many years to measure interfacial and surface tensions, but with the advent of computer data collection and computer control of dynamic test conditions, its utility has been greatly increased. The dynamic version of the Whilhelmy plate device, in which the liquid phases are in motion relative to a solid phase, has been used in several surface chemistry studies. This paper discusses the dynamic Whilhelmy plate apparatus used to study wetting properties of solid/liquid/liquid systems important to the oil industry. Heterogeneous mineral samples can be used easily in these studies andmore » oil-wetting versus water-wetting systems can quickly be distinguished. The use of this technique to make relative comparisons of the surface energies of minerals encountered in reservoirs is also discussed. This information gives a more basic understanding of reservoir rock wettability.« less