Optical Evaluation of the Effect of Curvature and Apparent Contact Angle in Droplet Condensate Removal

2002 ◽  
Vol 124 (4) ◽  
pp. 729-738 ◽  
Author(s):  
Ying-Xin Wang ◽  
Ling Zheng ◽  
Joel L. Plawsky ◽  
Peter C. Wayner,
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Removal Rate ◽  
Contact Angles ◽  
Transport Processes ◽  
Force Balance ◽  
Pressure Fields ◽  
Concave Corner ◽  
Microscale Transport ◽  
Droplet Condensation

The microscale transport processes in droplet condensation and removal due to interfacial phenomena were studied. In particular, this paper concerns the movement of a condensed ethanol sessile drop into a concave liquid film in the corner. An improved image analyzing procedure was used to evaluate the curvatures and contact angles for both the drop and the concave corner meniscus at different condensation rates. The experimental results demonstrated that the condensate removal rate was a function of the curvature and contact angle, which self-adjust to give the necessary force field. The use of a dimensionless, shape dependent, force balance was demonstrated. For small drops, the intermolecular force was found to be much larger than the gravitational force and dominated droplet removal. Microscale pressure fields can be experimentally measured whereas interfacial temperature differences cannot.

Comparative Study of Surface Energies of Native Oxides of Si(100) and Si(111) via Three Liquid Contact Angle Analysis

MRS Advances ◽  
2018 ◽  
Vol 3 (57-58) ◽  
pp. 3379-3390 ◽  
Author(s):  
Saaketh R. Narayan ◽  
Jack M. Day ◽  
Harshini L. Thinakaran ◽  
Nicole Herbots ◽  
Michelle E. Bertram ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Energy ◽  
Sessile Drop ◽  
Surface Composition ◽  
Ion Beam ◽  
Contact Angles ◽  
Van Der Waals Interactions ◽  
Native Oxides ◽  
Relative Errors ◽  
Contact Angle Analysis

ABSTRACTThe effects of crystal orientation and doping on the surface energy, γT, of native oxides of Si(100) and Si(111) are measured via Three Liquid Contact Angle Analysis (3LCAA) to extract γT, while Ion Beam Analysis (IBA) is used to detect Oxygen. During 3LCAA, contact angles for three liquids are measured with photographs via the “Drop and Reflection Operative Program (DROP™). DROP™ removes subjectivity in image analysis, and yields reproducible contact angles within < ±1°. Unlike to the Sessile Drop Method, DROP can yield relative errors < 3% on sets of 20-30 drops. Native oxides on 5 x 1013 B/cm3 p- doped Si(100) wafers, as received in sealed, 25 wafer teflon boats continuously stored in Class 100/ISO 5 conditions at 24.5°C in 25% controlled humidity, are found to be hydrophilic. Their γT, 52.5 ± 1.5 mJ/m2, is reproducible between four boats from three sources, and 9% greater than γT of native oxides on n- doped Si(111), which averages 48.1 ± 1.6 mJ/m2 on four 4” Si(111) wafers. IBA combining 16O nuclear resonance with channeling detects 30% more oxygen on native oxides of Si(111) than Si(100). While γT should increase on thinner, more defective oxides, Lifshitz-Van der Waals interactions γLW on native oxides of Si(100) remain at 36 ± 0.4 mJ/m2, equal to γLW on Si(111), 36 ± 0.6 mJ/m2, since γLW arises from the same SiO2 molecules. Native oxides on 4.5 x 1018 B/cm3 p+ doped Si(100) yield a γT of 39 ± 1 mJ/m2, as they are thicker per IBA. In summary, 3LCAA and IBA can detect reproducibly and accurately, within a few %, changes in the surface energy of native oxides due to thickness and surface composition arising from doping or crystal structure, if conducted in well controlled clean room conditions for measurements and storage.

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 Effect of Direct Current on Solid-Liquid Interfacial Tension and Wetting Behavior of Ga–In–Sn Alloy Melt on Cu Substrate

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Limin Zhang ◽  
Ning Li ◽  
Hui Xing ◽  
Rong Zhang ◽  
Kaikai Song
Keyword(s):  
Contact Angle ◽  
Interfacial Tension ◽  
Direct Current ◽  
Sessile Drop ◽  
Contact Angles ◽  
Current Intensity ◽  
Solute Diffusion ◽  
Wetting Behavior ◽  
Cu Substrate ◽  
Solid Liquid

The effect of direct current (DC) on the wetting behavior of Cu substrate by liquid Ga–25In–13Sn alloy at room temperature is investigated using a sessile drop method. It is found that there is a critical value for current intensity, below which the decrease of contact angle with increasing current intensity is approximately linear and above which contact angle tends to a stable value from drop shape. Current polarity is a negligible factor in the observed trend. Additionally, the observed change in contact angles is translated into the corresponding change in solid-liquid interfacial tension using the equation of state for liquid interfacial tensions. The solid-liquid interfacial tension decreases under DC. DC-induced promotion of solute diffusion coefficient is likely to play an important role in determining the wettability and solid-liquid interfacial tension under DC.

Wetting and Interfacial Behavior of Molten Al on Mo-Ni(Co)-Si Coated SiC Ceramic

2016 ◽  
Vol 697 ◽  
pp. 481-484 ◽  
Author(s):  
San Tuan Zhao ◽  
Xiang Zhao Zhang ◽  
Gui Wu Liu ◽  
Hong Yan Xia ◽  
Zhong Qi Shi ◽  
...  
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Triple Line ◽  
Contact Angles ◽  
Strong Interactions ◽  
Interfacial Behavior ◽  
Ceramic Substrates ◽  
Sic Ceramic ◽  
Mo Content ◽  
Drop Technique

The Mo-Ni (Co)-Si metallizing coatings on the SiC ceramic substrate were prepared by vacuum cladding process. The wetting and spreading of molten Al on coated SiC ceramic substrates at 900 oC were investigated by the sessile drop technique, and the interfacial behavior of the Al/coated SiC wetting couples was analyzed. The experimental results showed that the final contact angle of Al/M20NiSi coated SiC was close to 0o. With the increase of Mo content in the Mo-Ni-Si coating, the shape of the sessile drop became very irregular due to the strong interactions between the Al drop and the coating, so it was unable to precisely characterize the contact angles of Al/Mo30NiSi and Al/Mo40NiSi systems. The final contact angle of Al/Mo10CoSi coated SiC system was also close to 0o, however, the final contact angle of Al/Mo20CoSi coated SiC system climbed to ~42o with the Mo content increasing from 10 at.% to 20 at.%. The significant increase of contact angle may be caused by the accumulation of Mo near the triple line which can impede the spreading of Al drop.

A laser interferometric study of sessile drop shape and contact angle

1985 ◽  
Vol 63 (8) ◽  
pp. 2339-2340 ◽  
Author(s):  
R. N. O'brien ◽  
Paul Saville
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Contact Angles ◽  
Glass System ◽  
Drop Shape ◽  
Measured Angle ◽  
Interferometric Study ◽  
Laser Interferometric ◽  
Equal Thickness

Small contact angles, such as water on glass, have been shown to be measurable interferometrically using fringes of equal thickness after the fashion of Newton's rings. The measured angle for the water on glass system was 0.049 ± 0.006 degrees of arc.

Wetting of Compacted Nanoclay Powder by Epoxy Resin

Materials ◽  
2005 ◽  
Author(s):  
Levent Aktas ◽  
Youssef K. Hamidi ◽  
M. Cengiz Altan
Keyword(s):  
Contact Angle ◽  
Epoxy Resin ◽  
Sessile Drop ◽  
Ccd Camera ◽  
Contact Angles ◽  
Effect Of Temperature ◽  
Chemical Compositions ◽  
Low Viscosity ◽  
Static Contact ◽  
Advancing Contact Angle

Spreading behavior and advancing contact angle of a low viscosity epoxy resin on three commercially available nanoclays — Cloisite® Na+, Cloisite® 15A and Cloisite® 25A — at 52°C is investigated. In addition, effect of temperature on spreading dynamics of epoxy on Cloisite® Na+ is analyzed at 33, 52 and 77°C. For wetting experiments, nanoclay powder is compressed into 12.7mm diameter disk shaped compacts under 20MPa pressure. The surface topologies of the compacts are analyzed by scanning electron microscopy (SEM), where as energy dispersive x-ray analysis (EDXA) is utilized to quantify the chemical composition of the surface. An epoxy drop is placed on each of the compacts and spreading is monitored via a CCD camera equipped with a high magnification lens. Temporal evolution of the advancing contact angle as well as drop penetration into the nanoclay compact is determined using the drop profiles extracted from the sessile drop images. Spreading of epoxy on Cloisite® Na+ is observed to be 12-fold faster at 77°C compared to 33°C. Analogous to its spreading speed, rate of penetration of resin into the nanoclay compact increased 20-fold in the same temperature range. Behavior of different nanoclay types are assessed by repeating the wetting experiments on Cloisite® 15A and Cloisite® 25A compacts. Unlike Cloisite® Na+, which did not have a finite static contact angle, Cloisite® 15A and Cloisite® 25A yielded static contact angles of 59.2°and 40.1°, respectively. These differences are attributed to different surface energies as a result of different chemical compositions of the surfaces and dissimilar surface topologies.

Effects of Flow Regime on DOM Retention in Soils: Continuous Flow vs. Flow Interruption

2020 ◽  
Author(s):  
Jannis Florian Carstens ◽  
Georg Guggenberger ◽  
Jörg Bachmann
Keyword(s):  
Continuous Flow ◽  
Sessile Drop ◽  
Contact Angles ◽  
Transport Processes ◽  
Solid Matrix ◽  
Flow Conditions ◽  
Oxide Mineral ◽  
Flow Interruption ◽  
Flow Stagnation ◽  
Coated Sand

&lt;p&gt;Dissolved organic matter (DOM) is one of the most mobile components of the global carbon cycle. Corresponding transport processes in the environment have received plenty of attention in the context of carbon sequestration as well as the mobility of DOM-associated contaminants.&lt;/p&gt;&lt;p&gt;However, most previous transport studies have been conducted exclusively under continuous flow conditions, which are not comparable to real water flow characteristics in soil. The present study aims to address that gap in knowledge by systematically assessing the effect of defined flow interruption phases on the retention of DOM.&lt;/p&gt;&lt;p&gt;For that, the breakthrough behavior of DOM as affected by phases of flow interruption was investigated in an increasingly complex system of solid matrices rich in oxide mineral coatings: goethite coated quartz sand, disturbed Cambisol subsoil, and undisturbed Cambisol subsoil. The classic DLVO and extended DLVO (XDLVO) models including Lewis acid&amp;#8212;base parameters were applied based on measurements of sessile drop contact angles and zeta potentials. &amp;#160;&lt;/p&gt;&lt;p&gt;DOM retention was increasing with the duration of flow interruption, and retention was considerably higher in the soils than in goethite coated sand. After 112 hours of flow stagnation, DOM release from the soils was reduced to 16 to 22 % as compared to continuous flow conditions. The retention in the different solid matrix materials was well correlated with the respective amounts of oxalate and dithionite extractable oxide mineral phases. The DLVO model was capable of correctly predicting the mobility of DOM in goethite coated sand, but not in the soils, due to the fact that soil surface charge heterogeneities could not be measured. The XDVLO model predicted short-range hydrophilic repulsive interactions that may have contributed to the distinct tailing of the DOM breakthrough curves.&lt;/p&gt;&lt;p&gt;We conclude that the significant DOM retention during phases of flow stagnation phases shows that more complex flow regimes need to be considered in order to assess the mobility of DOM in soils. In fact, many previous studies excluding phases of flow stagnation likely overestimated the mobility of DOM in the environment.&lt;/p&gt;

scholarly journals Comparative analysis of inactivated wood surfaces

Holzforschung ◽  
2004 ◽  
Vol 58 (1) ◽  
pp. 22-31 ◽  
Author(s):  
M. Šernek ◽  
F. A. Kamke ◽  
W. G. Glasser
Keyword(s):  
Contact Angle ◽  
High Temperature ◽  
Wood Species ◽  
Sessile Drop ◽  
Surface Composition ◽  
Contact Angles ◽  
Southern Pine ◽  
Hydrogen Atoms ◽  
Yellow Poplar ◽  
Wood Surfaces

Abstract The surface inactivation of two wood species, yellow poplar (Liriodendron tulipifera) and southern pine (Pinus taeda), was studied following high temperature drying. Surface analysis involved X-ray photoelectron spectroscopy, sessile drop wettability and fracture mechanics of the adhesively-jointed surfaces. The results showed that wood drying at high temperature (i.e., >160 to 180 °C) caused modifications in surface composition. The oxygen to carbon ratio (O/C) decreased and the ratio of carbon atoms bonded to other carbon or to hydrogen atoms vis-à-vis carbons bonded to oxygen atoms (i.e., the C1/C2 ratio) increased with drying temperature. In addition, the contact angle increased with the temperature of exposure, but decreased with time. A dependence on wood species was evident: southern pine surfaces always exhibited higher contact angles than yellow poplar. Also, the rate of contact angle decline with time, dθ/dt, was found to vary with surface composition: this rate corresponded to O/C ratio-changes, especially in the case of southern pine. Southern pine was most susceptible to inactivation particularly when bonded with PF adhesive. Yellow poplar surfaces did not show significant inactivation when exposed to drying temperatures below ca. 180 °C. The results are explained by a relative enrichment of wood surfaces with non-polar substances, hydrophobic extractives and volatile organic compounds that 'become visually evident during the drying process at temperatures above ca. 160 °C. Little change was observed if drying temperatures remained below 150 °C.

WETTING BEHAVIOR OF Al–Mg ALLOYS ON CARBON FIBER FABRIC

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350036 ◽  
Author(s):  
WANG XU ◽  
WANG CHENCHONG ◽  
CHEN GUOQIN ◽  
YANG WENSHU ◽  
ZHANG ZHICHAO
Keyword(s):  
Contact Angle ◽  
Carbon Fiber ◽  
Sessile Drop ◽  
Contact Angles ◽  
Mg Alloys ◽  
Holding Time ◽  
Dominant Effect ◽  
Wetting Behavior ◽  
Fiber Fabric ◽  
Al Mg Alloys

In present work, the wetting behavior of carbon fiber and Al – Mg alloys (up to 17 wt.%) from 700°C to 1000°C was investigated by sessile drop method. Below 900°C, the contact angles decreased slightly with increase of temperature regardless of Mg amount. However, the contact angles decreased sharply at elevated temperature (above 900°C). Moreover, below 900°C, the contact angles decreased slightly with holding time, and significant decrease of contact angle with increase of holding time was found above 1000°C. All contact angle-holding time curves at 1000°C demonstrated three kinetic stages. It is observed that the contact angles decreased with Mg amount regardless of wetting temperature. The addition of Mg element will inhabit the nucleation and growth of Al 4 C 3 phase, which is unfavorable to the wetting behavior. However, the addition of Mg element will also decrease the surface energy, which demonstrates dominant effect and leads to the decrease of contact angles.

scholarly journals Aluminum Melt Filtration with Carbon Bonded Alumina Filters

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3962
Author(s):  
Claudia Voigt ◽  
Jana Hubálková ◽  
Tilo Zienert ◽  
Beate Fankhänel ◽  
Michael Stelter ◽  
...  
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Contact Angles ◽  
Apparent Contact Angle ◽  
Drop Test ◽  
Aluminum Melt ◽  
Wetting Behavior ◽  
Purification Unit ◽  
Conventional Test ◽  
Porous Disc

The wetting behavior was measured for Al2O3-C in contact with AlSi7Mg with a conventional sessile drop test (vacuum, 950 °C and 180 min) and a sessile drop test with a capillary purification unit (vacuum, 730 °C and 30 min). The conventional test yielded contact angles of around 92°, whereas the sessile drop measurement with capillary purification showed a strongly non-wetting behavior with a determined apparent contact angle of the rolling drop of 157°. Filtration tests, which were repeated twice, showed that the Al2O3-C filter possessed a better filtration behavior than the Al2O3 reference filter. For both filtration trials, the PoDFA (porous disc filtration analysis) index of the Al2O3-C filter sample was equal to half of the PoDFA index of the Al2O3 reference filter sample, indicating a significantly improved filtration performance when using Al2O3-C filter. Notable is the observation of a newly formed layer between the aluminum and the Al2O3-C coating. The layer possessed a thickness between 10 µm up to 50 µm and consisted of Al, C, and O, however, with different ratios than the original Al2O3-C coating. Thermodynamic calculations based on parameters of the wetting and filtration trials underline the possible formation of an Al4O4C-layer.

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