Wetting of solid copper with liquid indium in a superhigh vacuum and a gas medium and calculation of their interphase energies depending on the temperature

2021 ◽  
pp. 109-113
Author(s):  
M.P. Dokhov ◽  
◽  
E.Kh. Sherieva ◽  
M.N. Kokoeva ◽  
◽  
...  
Keyword(s):  
Contact Angle ◽  
Interfacial Energy ◽  
Direct Method ◽  
High Vacuum ◽  
Contact Angles ◽  
Liquid Phase Sintering ◽  
Urgent Task ◽  
Different Temperatures ◽  
Liquid Indium ◽  
Solid Copper

In the article, using the experimental data obtained in recent years on the contact angles and surface energies of solid copper and liquid indium, their interfacial energies are calculated at different temperatures. Knowledge of the interfacial characteristics is dictated by the need to obtain new materials that can operate under extreme conditions. For these and some other purposes in modern engineering and technology, they began, for example, to use high-vacuum brazing of high-temperature metal products using low-temperature metals and alloys. An important role in such processes is played by the interfacial energy at the solid-melt interface, which determines the contact angle: the lower the interfacial energy, the smaller the contact angle, and the smaller the contact angle, the better the processes of soldering, welding and liquid-phase sintering, etc. etc. Unfortunately, until now there is no direct method for measuring the interfacial energy. Therefore, the calculation of this value is an urgent task.

scholarly journals On the limitations of the applicability of Young’s equations temperature

2021 ◽  
Vol 23 (2) ◽  
pp. 218-222
Author(s):  
Magomed Pashevich Dokhov
Keyword(s):  
Contact Angle ◽  
Surface Energy ◽  
Interfacial Energy ◽  
Contact Angles ◽  
Surface Phenomena ◽  
Surface Energies ◽  
Three Phase ◽  
Production Techniques ◽  
The Difference ◽  
Solid Liquid

The article uses the thermodynamics of interfacial phenomena to justify the fact that Young’s equations can correctly describe the three-phase equilibrium with any type of interatomic bonds. Wetting, adhesion, dissolution, surface adsorption, and other surface phenomena are important characteristics, whichlargely determine the quality and durability of materials, and the development of a number of production techniques, including welding, soldering, baking of metallic and non-metallic powders, etc. Therefore, it is important to study them.Using experimental data regarding surface energies of liquids (melts) and contact angles available in the literature, we calculated the surface energies of many solid metals, oxides, carbides, and other inorganic and organic materials without taking into account the amount of the interfacial energy at the solid-liquid (melt) interface. Some researchers assumed that in case of an acute contact angle the interfacial energy is low. Therefore, they neglected it and assumed it to be zero.Others knew that this value could not be measured, that is why they measured and calculated the difference between the surface energy of a solid and the interfacial energy of a solid and a liquid (melt), which is equal to the product of the surface energy of this liquid by the cosine of the contact angle. It is obvious that these methods of determining the surface energy based on such oversimplified assumptions result in poor accuracy.Through the use of examples this paper shows how the surface energies of solids were previously calculated and how the shortcomings of previous calculations can be corrected

scholarly journals Laboratory measurements and model sensitivity studies of dust deposition ice nucleation

2012 ◽  
Vol 12 (16) ◽  
pp. 7295-7308 ◽  
Author(s):  
G. Kulkarni ◽  
J. Fan ◽  
J. M. Comstock ◽  
X. Liu ◽  
M. Ovchinnikov
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Dust Particles ◽  
Angle Distribution ◽  
Cloud Properties ◽  
Distribution Parameters ◽  
Different Temperatures ◽  
Single Contact

Abstract. We investigated the ice nucleating properties of mineral dust particles to understand the sensitivity of simulated cloud properties to two different representations of contact angle in the Classical Nucleation Theory (CNT). These contact angle representations are based on two sets of laboratory deposition ice nucleation measurements: Arizona Test Dust (ATD) particles of 100, 300 and 500 nm sizes were tested at three different temperatures (−25, −30 and −35 °C), and 400 nm ATD and kaolinite dust species were tested at two different temperatures (−30 and −35 °C). These measurements were used to derive the onset relative humidity with respect to ice (RHice) required to activate 1% of dust particles as ice nuclei, from which the onset single contact angles were then calculated based on CNT. For the probability density function (PDF) representation, parameters of the log-normal contact angle distribution were determined by fitting CNT-predicted activated fraction to the measurements at different RHice. Results show that onset single contact angles vary from ~18 to 24 degrees, while the PDF parameters are sensitive to the measurement conditions (i.e. temperature and dust size). Cloud modeling simulations were performed to understand the sensitivity of cloud properties (i.e. ice number concentration, ice water content, and cloud initiation times) to the representation of contact angle and PDF distribution parameters. The model simulations show that cloud properties are sensitive to onset single contact angles and PDF distribution parameters. The comparison of our experimental results with other studies shows that under similar measurement conditions the onset single contact angles are consistent within ±2.0 degrees, while our derived PDF parameters have larger discrepancies.

scholarly journals Laboratory measurements and model sensitivity studies of dust deposition ice nucleation

2012 ◽  
Vol 12 (1) ◽  
pp. 2483-2516 ◽  
Author(s):  
G. Kulkarni ◽  
J. Fan ◽  
J. M. Comstock ◽  
X. Liu ◽  
M. Ovchinnikov
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Dust Particles ◽  
Angle Distribution ◽  
Normal Contact ◽  
Cloud Properties ◽  
Different Temperatures ◽  
Single Contact

Abstract. We investigated the ice nucleating properties of mineral dust particles to understand the sensitivity of modeled cloud properties to different representations of contact angle in the Classical Nucleation Theory (CNT): onset single angle and probability density function (PDF) distribution approaches. These contact angle representations are based on two sets of laboratory deposition ice nucleation measurements: Arizona Test Dust (ATD) particles of 100, 300, and 500 nm sizes were tested at three different temperatures (−25, −30 and −35 °C), and 400 nm ATD and Kaolinite dust species were tested at two different temperatures (−30 and −35 °C). These measurements were used to derive the onset relative humidity with respect to ice (RHice) required to activate 1% of dust particles as ice nuclei, from which the onset single contact angles were then calculated based on the CNT. For the PDF representation, parameters of the log-normal contact angle distribution (mean and standard deviation) were determined by fitting the CNT-predicted activated fraction to the measurements at different RHice. Results show that onset single contact angles are not much different between experiments, while the PDF parameters are sensitive to those environmental conditions (i.e., temperature and dust size). The cloud resolving model simulations show that cloud properties (i.e. ice number concentration, ice water content, and cloud initiation times) are sensitive to onset single contact angles and PDF distribution parameters, particularly to the mean value. The comparison of our experimental results with other studies shows that under similar measurement conditions the onset single contact angles are consistent within ±2.0°, while our derived PDF parameters have discrepancies.

Correlation of Surface and Interfacial Energies on Enhanced Pool Boiling Heat Transfer

Volume 3 ◽  
2004 ◽  
Author(s):  
Elva Mele´ndez ◽  
Rene´ Reyes
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Surface Energy ◽  
Interfacial Energy ◽  
Boiling Heat Transfer ◽  
Contact Angles ◽  
Lauryl Sulfate ◽  
Surface Energies ◽  
Interfacial Energies ◽  
Set Up

The surface energy of the material used in the construction of capillary covers is an important element to increase the boiling heat transfer on the coverings. There are a variety of methodologies for measuring the surface energy of solids, but few could be used with the construction materials tested. The sessile drop methodology allows the evaluation of either the surface energy of solids or the interfacial energy of liquids. The methodology uses an image digitalization system for measuring the contact angle of liquids on the solid’s surface. The contact angles thus measured are used to calculate the superficial and interfacial energies. This methodology was tested with an experimental set up built for this study. The accuracy of the set up was obtained with clean and greased surfaces of high heat conductivity metals. The surface energies calculated were in accordance with previous experimental results. The surface energies of metal foils used for construction of capillary coverings were similar to the values calculated for the parental solid metal. The surfaces with different grease thickness get values of surface energy close to the value for the adhered hydrocarbons. The same methodology is used for measuring interfacial energies of pure and mixtures of liquids. The liquids studied include those used for increasing boiling heat transfer. Ethanol-water mixtures were analyzed. The mixture with 16% ethanol by weight had the lowest contact angle (associated to the lowest interfacial energy) and produced the highest convective heat transfer coefficient, h. A minimum in the value of the contact angle around the 16% weight ethanol mixtures follows the maximum in the value of h around this composition, and a maximum in the wettability. Similarly, the surfactant sodium-lauryl-sulfate (SLS) produced an increment of the wettability of the mixture on the solid surface. The reduction of the contact angle is obtained with the addition of 100 ppm of SLS or less, depending on the base metal, but above this concentration, the surfactant does not modify the value of the contact angle. The h values increased with the addition of surfactant up to 100 ppm but do not change if the concentration of surfactant is higher than that value.

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

scholarly journals Fabrication of elastic, conductive, wear-resistant superhydrophobic composite material

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seyed Mehran Mirmohammadi ◽  
Sasha Hoshian ◽  
Ville P. Jokinen ◽  
Sami Franssila
Keyword(s):  
Contact Angle ◽  
Composite Material ◽  
Contact Angles ◽  
Wet Etching ◽  
Sliding Angle ◽  
Electrically Conductive ◽  
Wear Resistant ◽  
Nanoscale Structures ◽  
Mechanical Abrasion ◽  
Mechanical Durability

AbstractA polydimethylsiloxane (PDMS)/Cu superhydrophobic composite material is fabricated by wet etching, electroless plating, and polymer casting. The surface topography of the material emerges from hierarchical micro/nanoscale structures of etched aluminum, which are rigorously copied by plated copper. The resulting material is superhydrophobic (contact angle > 170°, sliding angle < 7° with 7 µL droplets), electrically conductive, elastic and wear resistant. The mechanical durability of both the superhydrophobicity and the metallic conductivity are the key advantages of this material. The material is robust against mechanical abrasion (1000 cycles): the contact angles were only marginally lowered, the sliding angles remained below 10°, and the material retained its superhydrophobicity. The resistivity varied from 0.7 × 10–5 Ωm (virgin) to 5 × 10–5 Ωm (1000 abrasion cycles) and 30 × 10–5 Ωm (3000 abrasion cycles). The material also underwent 10,000 cycles of stretching and bending, which led to only minor changes in superhydrophobicity and the resistivity remained below 90 × 10–5 Ωm.

The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems

1998 ◽  
Vol 518 ◽  
Author(s):  
Sang-Ho Lee ◽  
Myong-Jong Kwon ◽  
Jin-Goo Park ◽  
Yong-Kweon Kim ◽  
Hyung-Jae Shin
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Fluorocarbon Films ◽  
Perfluorodecanoic Acid ◽  
Large Hysteresis ◽  
Static Contact ◽  
Receding Contact ◽  
Highly Hydrophobic ◽  
Receding Contact Angle

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.

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