The Relation between Contact Angle and Drop Size for Water at its Boiling Point for a Pressure Range 50–760 Torr

1972 ◽  
Vol 50 (15) ◽  
pp. 2419-2422 ◽  
Author(s):  
A. B. Ponter ◽  
A. P. Boyes
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Boiling Point ◽  
Pressure Range ◽  
Drop Size ◽  
Copper Surface ◽  
Contact Angles ◽  
Drop Diameter ◽  
Appreciable Change ◽  
Water Drops

Contact angles have been measured using water drops of specified sizes, and in equilibrium with their vapor only, at their boiling point when residing on a copper surface at pressures ranging from 50–760 Torr.No appreciable change of contact angle with drop diameter was evident for sizes of 0.5 cm or more, but below this value the angles were dependent on the drop diameter, the effect of reducing pressure being to increase the dependency. The phenomenon is qualitatively explained in terms of gravity and surface roughness influences.

scholarly journals Correlation between Contact Angle and Surface Roughness of Silicon Carbide Wafers

2021 ◽  
Author(s):  
Jung Gon Kim ◽  
Woo Sik Yoo ◽  
Woo Yeon Kim ◽  
Won Jae Lee
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Surface Polarity ◽  
Force Microscopy ◽  
Water Drops ◽  
The Difference ◽  
Sic Wafer

Abstract Two-inch diameter 6H-SiC wafers were sliced from a SiC ingot and the wafers were ground and polished using different diamond slurries (1 m and 0.1 m in particles size) to investigate their dependence on wetting on surface roughness (Ra) and polarity using precisely dispensed de-ionized (DI) water drops. The Ra of the Si-face (0001) SiC wafer, after grinding and polishing, was 5.6 and 1.6 nm, respectively, as measured by atomic force microscopy (AFM). For C-face (000-1) SiC wafers, the Ra was 7.2 nm after grinding and 3.3 nm after polishing. The average contact angle measurement of the SiC wafers after final polishing showed clear differences between surface polarity; the contact angle for the Si-face (0001) was ~7o greater than that for the C-face (000-1). The difference in contact angles between the Si-face (0001) and the C-face (000-1) tends to increase as the reduction of surface roughness approaches the final stage of polishing. The uniformity of Raman peak intensity in the folded transverse optical phonon band at ~780 cm-1 in scanned areas correlated well with the surface roughness measured by AFM. The contact angle measurement can be used as a convenient surface polarity and surface roughness testing technique for SiC wafers.

WETTING OF ROUGH SURFACES

2004 ◽  
Vol 11 (01) ◽  
pp. 7-13 ◽  
Author(s):  
XINPING ZHANG ◽  
SIRONG YU ◽  
ZHENMING HE ◽  
YAOXIN MIAO
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Sessile Drop ◽  
Test Sample ◽  
Contact Angles ◽  
Sessile Drop Method ◽  
Equilibrium Contact Angle ◽  
Roughness Surface ◽  
Solid Substrates ◽  
Effect Of Surface

This paper focuses on effects of roughness on wettability. According to Wenzel's equation, the transition of theoretical wetting contact angles is 90°, whereas many experimental results have indicated that such a transition takes place at contact angles smaller than 90°. A new model of wetting on roughness surface is established in this paper. The model indicates that the influencing factors of wetting on roughness surface include not only equilibrium contact angle θ0 and surface roughness, but also the system of liquids and solid substrates. There is a corresponding transition angle for every surface roughness, and the transition angle is lower than 90°. Surface roughness is propitious to improve the contact angle only when θ0 is lower than the transition angle. The effect of surface roughness on the contact angle increases with the increase of rE. To engineer the surface with different roughnesses, a Ti test sample is polished with sandpaper with abrasive number 350, 500, 1000 and 2000; the contact angles of water on Ti are measured by the sessile drop method. The results of the theoretical analysis agree with experimental ones.

scholarly journals Thermo-Responsive Wettability via Surface Roughness Change on Polymer-Coated Titanate Nanorod Brushes Toward Fast and Multi-Directional Droplet Transport

2020 ◽  
Author(s):  
Kenji Okada ◽  
Yoko Miura ◽  
Tomoya Chiya ◽  
Yasuaki Tokudome ◽  
Masahide Takahashi
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Contact Angles ◽  
Roughness Change ◽  
Scientific Advancement ◽  
Novel Approach ◽  
Droplet Transport ◽  
Titanate Nanostructures ◽  
Selection Of ◽  
Smart Surface

A novel approach for thermo-responsive wettability has been accomplished by surface roughness change induced by thermal expansion of paraffin coated on titanate nanostructures. The surface exhibits thermo-responsive and reversible wettability change in a hydrophobic regime; the surface shows superhydrophobicity with contact angles of ~157° below 50 °C and ~118° above 50 °C due to a decrease of surface roughness caused by thermally-expanded paraffin at higher temperatures. Reversible wettability change of ~40° of a contact angle allows for a fast and multi-directional droplet transport. The present approach affords versatile selection of materials and wide variety of the contact angle, promoting both scientific advancement and technology innovation in the field of smart surface.

Contact angles and hysteresis, with some reference to flotation research

1977 ◽  
Vol 30 (1) ◽  
pp. 205 ◽  
Author(s):  
IW Wark
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Gas Phase ◽  
Water Vapour ◽  
Relative Motion ◽  
Solid Surface ◽  
Contact Angles ◽  
Russian School ◽  
Angle Measurements ◽  
Contact Angle Measurements

A technique used in flotation research for contact angle measurements is recommended for wider use. The effect of one aspect of surface roughness on the relative motion of fluid/solid systems is discussed. The function of the water vapour present in the gas phase adjacent to the line of triple contact is examined. A claim of the Russian school of surface chemists is questioned, namely, that a discrete film of water on the solid surface invariably dominates both hysteresis and contact angle.

Lattice Boltzmann simulation of immiscible displacement in the cavity with different channel configurations

2017 ◽  
Vol 28 (11) ◽  
pp. 1750136 ◽  
Author(s):  
Qin Lou ◽  
Chenqiang Zang ◽  
Mo Yang ◽  
Hongtao Xu
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Lattice Boltzmann ◽  
Contact Angles ◽  
Surface Wettability ◽  
Immiscible Displacement ◽  
Displacement Efficiency ◽  
Small Contact Angle ◽  
Gas Cavity ◽  
Pseudo Potential

In this work, the immiscible displacement in a cavity with different channel configurations is studied using an improved pseudo-potential lattice Boltzmann equation (LBE) model. This model overcomes the drawback of the dependence of the fluid properties on the grid size, which exists in the original pseudo-potential LBE model. The approach is first validated by the Laplace law. Then, it is employed to study the immiscible displacement process. The influences of different factors, such as the surface wettability, the distance between the gas cavity and liquid cavity and the surface roughness of the channel are investigated. Numerical results show that the displacement efficiency increases and the displacement time decreases with the increase of the surface contact angle. On the other hand, the displacement efficiency increases with increasing distance between the gas cavity and the liquid cavity at first and finally reaches a constant value. As for the surface roughness, two structures (a semicircular cavity and a semicircular bulge) are studied. The comprehensive results show that although the displacement processes for both the structures depend on the surface wettability, they present quite different behaviors. Specially, for the roughness structure constituted by the semicircular cavity, the displacement efficiency decreases and displacement time increases evidently with the size of the semicircular cavity for the small contact angle. The trend slows down as the increase of the contact angle. Once the contact angle exceeds a certain value, the size of the semicircular cavity almost has no influence on the displacement process. While for the roughness structure of a semicircular bulge, the displacement efficiency increases with the size of bulge first and then it decreases for the small contact angle. The displacement efficiency increases first and finally reaches a constant for the large contact angle. The results also show that the displacement time has an extreme value in these cases for the small contact angles.

The Effect of Solid Surface Roughness on Dynamic Contact Angles in Solid-Liquid-Liquid Systems

2002 ◽  
Author(s):  
Dandina N. Rao ◽  
Hussain H. Radwani
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Solid Surface ◽  
Water System ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Liquid Systems ◽  
L Systems ◽  
Solid Liquid

The engineering applications of spreading and adhesion phenomena involving fluids on solids are numerous. The adhesive and spreading interactions at the solid-fluid interfaces are well characterized by dynamic contact angles. This study reports on the results of an experimental investigation into the effect of solid surface roughness on dynamic contact angles in solid-liquid-liquid (S-L-L) systems. The experiment involved the use of Wilhelmy Plate apparatus to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle between the liquid-liquid interface and the solid surface), the DuNuoy tensiometer to measure the liquid-liquid interfacial tension, and a profilometer to characterize the roughness of the solid surfaces used. The components of the solid-liquid-liquid systems studied consisted of: (i) smooth glass, roughened quartz and an actual rock surface for the solid phase, (ii) normal-hexane and deionized water as the two immiscible liquid phases. The dynamic contact angles (advancing and receding angles) of the three-phase (rock-oil-water) system provide essential information about the wettability of petroleum resrvoirs. The wettability of a reservoir is an important parameter that affects oil recovery in primary, secondary, and enhanced recovery operations [1]. Contact angle measurements on smooth surfaces are generally used to characterize reservoir wettability. However pore surfaces within reservoir rocks are essentially rough and hence it is important to determine the effect of such roughness on measured contact angles. There is very little information in the open literature on the effect of surface roughness on dynamic contact angles in S-L-L systems. In the present work, four levels of roughness of solid surfaces of similar mineralogy (quartz and glass) were tested in hexane-deionized water fluid pair. The advancing and receding contact angles measured at ambient conditions were analyzed for wettability effects. It was found that as surface roughness increased, the dynamic contact angles also increased. The wettability of the rock-oil-water system shifted from weakly water-wet for the smooth glass to intermediate-wet for the roughened surface. The general trends observed in our study were found to be in good agreement with other published results. However, the generally held notion of increasing contact angle hysteresis with increasing roughness appears to be incorrect in solid-liquid-liquid systems.

The Wetting of Insect Cuticles by Water

1955 ◽  
Vol 32 (3) ◽  
pp. 591-617 ◽  
Author(s):  
M. W. HOLDGATE
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Surface Composition ◽  
Contact Angles ◽  
Aquatic Species ◽  
Water Contact ◽  
Calliphora Erythrocephala ◽  
Wetting Properties ◽  
Wide Range

1. The water contact angles of insects show a wide range of variation, which is broadly correlated with surface roughness and with habitat. 2. The contact angles of species inhabiting stored products or carrion are greatly modified by contamination. This produces large variations between apparently similar individuals. 3. In terrestrial insects surface roughness increases the contact angles to very large apparent values. Detailed analyses of its effect have been made in the pupa of Tenebrio molitor and the adult Calliphora erythrocephala. In some aquatic insects surface roughness leads to a reduction in the contact angles; this has been studied in the nymph of Anax imperator. 4. Prolonged immersion in water causes a lowering of the contact angles of all the insects examined, and the low angles of many aquatic species may therefore be the direct effect of their environment. In some aquatic species there is evidence of the active maintenance of a large contact angle during life. 5. Changes in contact angle accompany processes of cuticle secretion and will occur at any moult if changes in roughness or habitat take place. 6. The observed variations of surface properties can be explained without assuming any variation in the chemical composition of the cuticle surface. Wetting properties are of little value as indicators of cuticle surface composition. 7. The biological aspects of insect surface properties are briefly discussed.

Roughness Effects on Continuous and Discrete Flows in Superhydrophobic Microchannels

2011 ◽  
Vol 9 (5) ◽  
pp. 1094-1105 ◽  
Author(s):  
Junfeng Zhang ◽  
Daniel Y. Kwok
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Slip Length ◽  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Lattice Boltzmann Model ◽  
Roughness Effects ◽  
Apparent Slip ◽  
Velocity Changes

AbstractThe dynamic behaviors of continuous and discrete flows in superhydrophobic microchannels are investigated with a lattice Boltzmann model. Typical characters of the superhydrophobic phenomenon are well observed from our simulations, including air trapped in the surface microstructures, high contact angles, low contact angle hysteresis, and reduced friction to fluid motions. Increasing the roughness of a hydrophobic surface can produce a large flow rate through the channel due to the trapped air, implying less friction or large apparent slip. The apparent slip length appears to be independent to the channel width and could be considered as a surface property. For a moving droplet, its behavior is affected by the surface roughness from two aspects: the contact angle difference between its two ends and the surface-liquid interfacial friction. As a consequence, the resulting droplet velocity changes with the surface roughness as firstly decreasing and then increasing. Simulation results are also compared with experimental observations and better agreement has been obtained than that from other numerical method. The information from this study could be valuable for microfluidic systems.

scholarly journals Preparation of Superhydrophobic Teflon® AF 1600 Sub-Micron Fibers and Yarns Using the Forcespinningtm Technique

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Yatinkumar Rane ◽  
Aleksey Altecor ◽  
Nelson S. Bell ◽  
Karen Lozano
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Average Diameter ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Sem Analysis ◽  
Fiber Formation ◽  
Excellent Thermal Stability ◽  
Wetting Properties

Superhydrophobic materials combined with manufacturing processes that can increase surface roughness of the material, offer an opportunity to effectively control wetting properties. Rapid formation of Teflon® AF (TAF) fibrous mats with sub-micron fiber diameter using the Forcespinning™ technique is presented. The fiber formation technique is based on the use of centrifugal forces. SEM analysis shows uniform formation of TAF 1600 fibers with average diameter of 362±58nm. Contact angle measurement confirms the superhydrophobic nature of the mats with contact angles as high as 169° ± 3° and rolling angles of 2°. TAF 1600 mats were forcespun at a rate of 1gr/min. The relationship between the contact angle and hierarchical surface roughness of the TAF mat is also discussed. TAF yarns were also manufactured and characterized. Yarns with diameters of 156 microns withstood 17.5 MPa of engineering stress with a Young's modulus of 348 MPa in the elastic region and excellent thermal stability.

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