Showing papers on "Sessile drop technique published in 2022"
TL;DR: In this article, an experimental study on hydrodynamics and heat transport during the horizontal coalescence of two drops impinging a hot wall was conducted under pure vapor atmosphere with the refrigerant FC-72 at a saturation temperature of 54 ° C, corresponding to a system pressure of 0.94 bar.
11 citations
TL;DR: In this paper, a statistical distribution of the surface tension of cork is obtained, based on experiments performed on cork powder with various liquids and using a specific data processing to take into account the intrinsic heterogeneity of Cork.
9 citations
TL;DR: In this article , the authors examined the known experience of measuring contact angles and suggested a simple equipment that allows the membrane to remain swollen during measurements, which makes it possible to obtain reliable and reproducible results.
Abstract: The contact angle between a membrane surface and a waterdrop lying on its surface provides important information about the hydrophilicity/hydrophobicity of the membrane. This method is well-developed for solid non-swelling materials. However, ion-exchange membranes (IEMs) are gel-like solids that swell in liquids. When an IEM is exposed to air, its degree of swelling changes rapidly, making it difficult to measure the contact angle. In this paper, we examine the known experience of measuring contact angles and suggest a simple equipment that allows the membrane to remain swollen during measurements. An optimized protocol makes it possible to obtain reliable and reproducible results. Measuring parameters such as drop size, water dosing speed and others are optimized. Contact angle measurements are shown for a large number of commercial membranes. These data are supplemented with values from other surface characteristics from optical and profilometric measurements.
9 citations
TL;DR: In this paper , a statistical distribution of the surface tension of cork is obtained, based on experiments performed on cork powder with various liquids and using a specific data processing to take into account the intrinsic heterogeneity of Cork.
9 citations
TL;DR: In this paper , the surface modification methods included polishing, laser texturing, low-temperature annealing, magnetron chromium sputtering, and their combination, and the graphic-analytical method was developed to predict the type of a texture formed after nanosecond laser radiation.
Abstract: Controlling the surface wetting of silicon carbide (SiC) ceramics is an urgent problem as its solution will significantly expand the scope of this material. In this work, the submicron SiC ceramics was obtained from the ultradispersed SiC powder fabricated by the plasma dynamic synthesis method. The bulk SiC samples were produced by spark plasma sintering at 1600 °С, 1700 °С, and 1800 °С. The effect of sintering temperature and promising methods of surface modification on wetting, elemental composition and surface roughness of SiC ceramics was studied. The surface modification methods included polishing, laser texturing, low-temperature annealing, magnetron chromium sputtering, and their combination. To predict the type of a texture formed after nanosecond laser radiation, the graphic-analytical method was developed. The best hydrophilic properties of SiC ceramics (the contact angle decreased to 9.3°) were obtained after polishing with subsequent nanosecond laser texturing. The best hydrophobic properties of SiC ceramics (the contact angle increased to 135.3°) were obtained after a combination of polishing, laser texturing, and magnetron chromium sputtering. Controlling the surface wetting of SiC ceramics from hydrophilic to hydrophobic makes it possible to significantly expand the scope of this material, for example, to use it in drop cooling systems of advanced digital devices that emit ultrahigh heat fluxes up to 1000 W/cm2.
8 citations
TL;DR: In this article, a theory for deducing liquid-liquid interfacial tensions from apparent contact angles of droplets on a sessile liquid-infused porous surface (SLIPS) was presented.
Abstract: Slippery liquid-infused porous surfaces (SLIPS) are an innovation that reduces droplet-solid contact line pinning and interfacial friction. Recently, it has been shown that a liquid analogue of Young’s law can be deduced for the apparent contact angle of a sessile droplet on SLIPS despite there never being contact by the droplet with the underlying solid. Since contact angles on solids are used to characterize solid–liquid interfacial interactions and the wetting of a solid by a liquid, it is our hypothesis that liquid–liquid interactions and the wetting of a liquid surface by a liquid can be characterized by apparent contact angles on SLIPS. Here, we first present a theory for deducing liquid–liquid interfacial tensions from apparent contact angles. This theory is valid irrespective of whether or not a film of the infusing liquid cloaks the droplet–vapor interface. We show experimentally that liquid–liquid interfacial tensions deduced from apparent contact angles of droplets on SLIPS are in excellent agreement with values from the traditional pendant drop technique. We then consider whether the Zisman method for characterizing the wettability of a solid surface can be applied to liquid surfaces created using SLIPS. We report apparent contact angles for a homologous series of alkanes on Krytox-infused SLIPS and for water–IPA mixtures on both the Krytox-infused SLIPS and a silicone oil-infused SLIPS. The alkanes on the Krytox-infused SLIPS follow a linear relationship in the liquid form of the Zisman plot provided that the effective droplet–vapor interfacial tension is used. All three systems follow a linear relationship on a modified Zisman plot. We interpret these results using the concept of the critical surface tension (CST) for the wettability of a solid surface introduced by Zisman. In our liquid surface case, the obtained critical surface tensions were found to be lower than the infusing liquid–vapor surface tensions.
8 citations
TL;DR: In this paper , the apparent contact angles of the CaO-Al2O3-SiO2-MgO slags on microporous magnesia aggregate (MM) and fused magnesia (FM) substrates were respectively measured by sessile drop method under Ar atmosphere at 1550 °C.
8 citations
TL;DR: In this paper , the authors combined experiments and numerical simulation to design a specific sessile drop approach where the liquid is removed before cooling down, which activates or suppresses the solute (carbon) transport by an AC magnetic field and thus separates the physical-chemical and hydrodynamic contributions.
Abstract: Accurate description, understanding and control of the high temperature interface behavior between the SiC single crystal and liquid phase is critical for further development of SiC solution growth. The different parameters which create morphological instabilities, such as step bunching, micro-faceting and solvent trapping, remain unclear because they are very difficult to address in high temperature experiments. We combined experiments and numerical simulation to design a specific sessile drop approach where the liquid is removed before cooling down. The advantage of this method that it activates or suppresses the solute (carbon) transport by an AC magnetic field and thus separates the physical–chemical and hydrodynamic contributions. The method was demonstrated through observation of the morphological evolution of a 4°off 4H-SiC (0001) surface in contact with pure liquid silicon at 1600 °C according to the time factor. Several parasitic effects were also analyzed and suppressed in order to obtain a well-controlled uniform interface.
6 citations
6 citations
TL;DR: Wang et al. as mentioned in this paper investigated the high-temperature wetting behavior of molten Ag with Ti3AlC2 and proposed a wetting mechanism based on interfacial structure and chemical composition.
6 citations
TL;DR: In this article , the effect of incubation in selected ophthalmic fluids on contact lenses was evaluated using the surface free energy (SFE) and the contact angle (CA) calculated with the use of several methods.
Abstract: This study attempts to evaluate the effect of incubation in selected ophthalmic fluids on contact lenses (Etafilcon A, Omafilcon A, Narafilcon A, Senofilcon A). Four research groups differing in the incubation environment were created: (1) initial state, (2) contact lens solution (CLS), (3) contact lens solution and eye drops (ED) and (4) eye drops. Dehydration by gravimetric method and the contact angle (CA) by the sessile drop method were tested. The surface free energy (SFE) was also calculated with the use of several methods: Owens–Wendt, Wu, Neumann, and Neumann–Kwok. The greatest changes in the dehydration profile were observed for contact lenses incubated in ED. The most noticeable changes in CA values were observed for contact lenses incubated in ED, in which it was not possible to settle water drop after incubation. On the basis of SFE analysis, higher values were found for hydrogel contact lenses, e.g., according to the Owens–Wendt method, they ranged from 54.45 ± 6.56 mJ/m2 to 58.09 ± 4.86 mJ/m2, while in the case of silicone-hydrogel contact lenses, they ranged from 32.86 ± 3.47 mJ/m2 to 35.33 ± 6.56 mJ/m2. Incubation in all tested environments decreased the SFE values, but the differences were in most cases statistically insignificant. Calculating the SFE may be a useful method as it can be used to estimate the possibility of bacteria adhering to contact lens surfaces.
TL;DR: In this article , a strategy to control the dried patterns of aqueous colloidal drop by controlling the drop configurations and relative humidity was proposed, and the results of different interactions between the Marangoni and buoyancy-induced natural convections in the sessile and pendant drops were studied.
TL;DR: In this paper, the effects of laser texturing on the wetting behavior of Al/SiC systems are investigated by modified sessile drop method, where the surface of SiC is textured by nanosecond laser with ordered square grids.
Abstract: Recently ultrafast laser has been used to process materials to obtain functional surface. However, most of the existing research is focused on metals, and only a few studies considered ceramics. In the current work, the effects of laser texturing on the wetting behavior of Al/SiC systems is investigated by modified sessile drop method. The surface of SiC is textured by nanosecond laser with ordered square grids. Then, the wetting behaviors of Al on both raw and textured SiC are investigated. The processed SiC surface and wetting interface are characterized by XPS, SEM, and XRD. Finally, the spreading kinetics is calculated. It is observed that laser texturing induces the melting and elimination of SiC, resulting in the generation of microsynapses and deposited carbon in grooves. The microstructure and chemical composition enhance the interfacial reaction, which results in faster spreading speed (spreading kinetics kr increases from 0.0041 to 0.011 at 1273 K) and higher wettability (final contact angle θ decreases from 78° to 42°). In addition, a considerably lower activation energy of spreading (164 kJ/mol) is obtained. The results demonstrate that laser processing is an effective method to enhance the wettability of metals on ceramics.
TL;DR: Wang et al. as discussed by the authors investigated the high-temperature wetting behavior of molten Ag with Ti3AlC2 and proposed a wetting mechanism based on the interfacial structure and chemical composition.
TL;DR: In this article, a strategy to control the dried patterns of aqueous colloidal drop by controlling the drop configurations and relative humidity was proposed, and the results of different interactions between the Marangoni and (buoyancy-induced) natural convections in the sessile and pendant drops were studied.
TL;DR: In this article, the authors investigated the reactive spreading of liquid aluminum on solid Ni by using the combined pendant/sessile drop method between 750 and 950 degrees C. The effects of interrelated multi-factors, including intermetallic compounds (IMCs) formation and diffusion on wetting dynamics is still debatable.
TL;DR: In this paper , the authors investigated the wetting behavior of two titanium surfaces, sandblasted and double acid etched (group S/E) and sandblasting group S, using blood and Autologous Platelet Liquid (APL).
Abstract: Physicochemical properties of titanium surfaces, such as wettability, influence protein binding, cell adhesion and proliferation, therefore osseointegration. The objective of this study was to investigate the wetting behaviour of two titanium surfaces, sandblasted and double acid etched (group S/E) and sandblasted (group S), using blood and Autologous Platelet Liquid (APL). Surface morphology and roughness were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The static contact angle (CA) was assessed with the sessile drop technique. The work also evaluates, with SEM observation, the fibrin clot structure that develops from blood and APL, knowing that a greater clot, firmly attached to an implant can facilitate cell migration to the implant interface. Both surfaces exhibited a hydrophobic behaviour, regardless of the wetting liquid used, but the S surface showed higher CA values for both the wetting fluids used. Lower CA values on the S/E surface are attributable to the different surface energy, which depends on different surface topography (the S surfaces were rougher) and on chemical composition. No statistically significant differences between the values of CA of blood and APL were found on the same surfaces. The clot obtained from whole blood differs from the APL clot due to a different cellular composition and fibrin density.
TL;DR: In this article , an analytical model for drop evaporation in gaseous environments that accounts for the effect of Stefan flow and temperature dependence of the thermo-physical properties is extended to the case of sessile drops.
TL;DR: In this article, the temperature dependence of surface/interfacial properties of liquid at elevated temperatures is studied by using sessile drop and pendant drop methods, and a decreasing trend of the initial surface tension and contact angle (CA) is observed with the increase of temperature.
TL;DR: In this paper , the wettability of molten CaO-Al2O3-MgO-FeO slag on BN substrate was investigated in a wide range of temperatures from 1673 to 1773K.
Abstract: The interface characterization is one of the important properties of molten slag, which has a significant influence on the interface phenomenon of molten slag and the reaction between slag and metal. The wettability of molten CaO–Al2O3–MgO–FeO slag on BN substrate was investigated in a wide range of temperatures from 1673 to 1773K. The FeO content was varied from 0 to 15 wt%. The contact angle was measured by the sessile drop method, the surface tension and interfacial tension were calculated by Dorsey method and Young's equation, respectively. The effects of the FeO content and temperature on the contact angle, surface tension and interfacial tension were discussed. The results indicated that the initial contact angle decreases with the increase of temperature and FeO content. And the wetting reaction between BN substrate and the selected molten slag is non-reactive wetting. The surface tension of the selected molten slag is in the range of 586–616 mN/m, and the surface tension decrease with the increase of FeO content and temperature. The value of interfacial tension between the selected molten slag and BN substrate is close to that of the surface tension, and the interfacial tension is 211–375 mN/m. The trend that the interfacial tension changes with the FeO content and temperature was the same as the trend that surface tension changes with the FeO content and temperature. Changes in the interfacial tension were correlated with modifications in the slag structure when FeO is added. The interfacial tension linearly decreases with increasing the optical basicity, which can provide a global measure of the concentrations of free oxygen ion in molten slag.
TL;DR: In this paper , an analytical model for predicting the competitive evaporation of two and three sessile drops is proposed, based on an analytical solution, in terms of Mehler functions, of the steady species and energy conservation equations for the gaseous phase.
Abstract: An analytical model for predicting the competitive evaporation of two and three sessile drops is proposed, based on an analytical solution, in terms of Mehler functions, of the steady species and energy conservation equations for the gaseous phase. The assessment through a comparison with accurate numerical solutions of the species conservation equations is reported in order to quantify the accuracy of the analytical solution. The model is validated against three available sets of experiments on two and three sessile drops on a line array. The decrease of the evaporation rate caused by the vicinity of sessile drops is reported in terms of a screening coefficient given by a relatively simple analytical expression. The influence of wall wettability on the evaporation of pairs of sessile drops is analyzed, and a parameter is proposed to quantify the effect of geometry in a unified way.
TL;DR: Wettability and interfacial reactivity of various ceramics in contact with molten AZ91 were investigated in this article , where modified sessile-drop tests were conducted, measuring contact angles between the ceramic substrates and molten AZ 91 droplets at 680 °C.
Abstract: Wettability and interfacial reactivity of various ceramics (ZrO2, Al2O3, Al2O3-C, MgO, MgAlON) in contact with molten AZ91 were investigated in this paper. MgAlON and Al2O3-C are new materials to be used in magnesium melt filtration, a comparative study of its wettability and corrosion resistance is performed to evaluate their applicability. Modified sessile-drop tests were conducted, measuring contact angles between the ceramic substrates and molten AZ91 droplets at 680 °C; contact surfaces were analyzed by means of scanning electron microscopy. MgAlON showed the largest contact angles, indicating lowest wettability. Al2O3, Al2O3-C, and MgO proved non-wettable as well. Al2O3- and ZrO2-containing substrates underwent noticeable interface reactions with molten AZ91.
TL;DR: In this paper , the authors used the sessile drop method to predict the contact angle of water on metal surfaces, which was shown to decrease linearly with increasing the atomic radius of the substrate.
Abstract: The wetting behavior of water on metal surfaces is important for a wide range of industries, for example, in the metallurgical industry during the preparation of metallic nanoparticles or electrochemical or electroless coating preparation from aqueous solutions, as well as in the construction industry (e.g., self-cleaning metal surfaces) and in the oil industry, in the case of water–oil separation or corrosion problems. Wettability in water/metal systems has been investigated in the literature; nevertheless, contradictions can be found in the results. Some papers have reported perfect wettability even in water/noble metal systems, while other researchers state that water cannot spread well on the surface of metals, and the contact angle is predicted at around 60°. The purpose of this paper is to resolve this contradiction and find correlations to predict the contact angle for a variety of metals. In our research, the wetting behavior of distilled water on the freshly polished surface of Ag, Au, Cu, Fe, Nb, Ni, Sn, Ti, and W substrates was investigated by the sessile drop method. The contact angle of the water on the metal was determined by KSV software. The contact angle of water is identified as being between 50° and 80°. We found that the contact angle of water on metals decreases linearly with increasing the atomic radius of the substrate. Using our new equation, the contact angle of water was identified on all of the metals in the periodic table. From the measured contact angle values, the adhesion energy of the distilled water/metal substrate interface was also determined and a correlation with the free electron density parameter of substrates was determined.
TL;DR: In this paper , the effects of laser texturing on the wetting behavior of Al/SiC systems are investigated by modified sessile drop method, where the surface of SiC is textured by nanosecond laser with ordered square grids.
Abstract: Recently ultrafast laser has been used to process materials to obtain functional surface. However, most of the existing research is focused on metals, and only a few studies considered ceramics. In the current work, the effects of laser texturing on the wetting behavior of Al/SiC systems is investigated by modified sessile drop method. The surface of SiC is textured by nanosecond laser with ordered square grids. Then, the wetting behaviors of Al on both raw and textured SiC are investigated. The processed SiC surface and wetting interface are characterized by XPS, SEM, and XRD. Finally, the spreading kinetics is calculated. It is observed that laser texturing induces the melting and elimination of SiC, resulting in the generation of microsynapses and deposited carbon in grooves. The microstructure and chemical composition enhance the interfacial reaction, which results in faster spreading speed (spreading kinetics kr increases from 0.0041 to 0.011 at 1273 K) and higher wettability (final contact angle θ decreases from 78° to 42°). In addition, a considerably lower activation energy of spreading (164 kJ/mol) is obtained. The results demonstrate that laser processing is an effective method to enhance the wettability of metals on ceramics.
TL;DR: In this article , the authors investigated the reactive spreading of liquid Al on solid Ni by using the combined pendant/sessile drop method between 750 and 950 °C, and they found that the effects of Ni dissolution into Al on the spreading dynamics were limited due to the low Ni solubility below 950°C.
15 Mar 2022
TL;DR: In this paper , the influence of adding silicon dioxide nanoparticles (nano-SiO2) to soft relining materials on C. albicans adhesion, surface roughness, and contact angle was evaluated.
Abstract: This study aimed at determining the influence of adding silicon dioxide nanoparticles (nano-SiO2) to soft relining materials on C. albicans adhesion, surface roughness, and contact angle.Eighty heat-polymerized acrylic resin disks were constructed and relined by using auto-polymerized acrylic soft liners (COE-SOFT, GC Co., Tokyo, Japan). The specimens were categorized into two groups according to the tests conducted. Group A was composed of 40 specimens for evaluating antifungal activity, and Group B was composed of 40 specimens for testing surface roughness and contact angle. Each group was subcategorized into four subgroups (n = 10) according to the concentration of nano-SiO2 added to the soft-liner powder: control, 0.25%, 0.5%, and 1.0% by weight. The colony forming unit (CFU) was used to assess C. albicans count. A profilometer was used to measure the surface roughness values (Ra; μm). The sessile drop method was used to evaluate the contact angle (o) by using a goniometer. Analysis of variance and Tukey's post hoc tests (α = 0.05) were used for the data analysis.In comparison with the unmodified group, the 0.25% and the 0.5% nano-SiO2 groups exhibited significantly lower C. albicans counts (P < 0.001), surface roughness (P < 0.001), and contact angles (P < 0.001). The exception was the 1% group, which exhibited higher C. albicans count, surface roughness, and contact angles than lower-concentration nano-SiO2 groups; however, these values in the 1% group were still less than their respective values in the control group.The addition of 0.25% and 0.5% nano-SiO2 to an auto-polymerized acrylic soft liner decreased C. albicans adhesion, surface roughness, and contact angle.
TL;DR: In this article , the effect of the nickel and the sulfur content on the contact angle between hBN-SiC-ZrO2-substrate and Cr-Mn-Ni-alloys was investigated in a 90 vol% N2/10 vol% H2 atmosphere in the temperature range of 1500 °C-1600 °C.
TL;DR: In this article , the influence of face milling, sanding and UV irradiation of the hornbeam and ash wood sample on the wetting and adhesion strength of solvent-based and water-borne coating was studied.
Abstract: In this research, the influence of face milling, sanding and UV irradiation of the hornbeam and ash wood sample on the wetting and adhesion strength of solvent-based and water-borne coating was studied. The adhesion of coatings to substrates is one of the most important parameters for finishing quality and service life of wood coatings, while wetting properties are usually used to assess the quality of surfacing process and could also provide important information on the adhesion ability of coatings. Surface roughness, contact angle of coatings and water as well as adhesion strength of coatings were tested on differently prepared (face milled, sanded and UV irradiated) samples of unmodified and thermally modified ash and hornbeam wood. Surface roughness was measured with stylus-type profilometer over the traverse of 12.5 mm and with a cut-off value of 2.5. Contact angle was measured using the sessile drop method 2 s, 10 s and 30 s after the application of the liquid drop on the sample surface, and adhesion strength was measured according to ASTM D4541. Results showed that sanding of hornbeam and ash wood resulted in the least rough surface compared to the face milled and UV irradiated surface. Contact angles of the water-borne coating were on average three times higher than the contact angles of the solvent-based coating. Sanding the surface of hornbeam and ash samples increased the adhesive strength in relation to the face milled surface, while UV irradiation of the sanded surface decreased the adhesive strength of most samples coated with solvent-based coating.
TL;DR: In this article , a numerical model is developed for sessile drop evaporation on a heated substrate under microgravity based on the results of rocket and parabolic experiments to understand the internal dynamics of a Sessile Drop.