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The study involved measurements of surface tension of liquid binary copper-titanium alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy–refractory material-gaseous phase system wettability using usual refractory materials, i.e., graphite, aluminum oxide and magnesium oxide. The experiments were performed with the use of the sessile drop method and a high-temperature microscope coupled with a camera and a computer. The aim of this study was to determine the influence of titanium content in the Cu-Ti alloy on the surface tension and contact angle at the interface between the liquid alloy and the refractory material. The influence of temperature on these parameters was also examined. The tests were carried out for copper-titanium alloys with a maximum content of 1.5% wt. Ti, in the temperature range of 1373 to 1573 K. The test results indicate that as the titanium content in the alloy increases, its surface tension increases slightly. However, an increase in temperature causes a decrease in the surface tension of the alloys. In the case of an alloy containing 1.5% wt. Ti, surface tension at a temperature of 1373 K reaches 1351 mN∙m−1, and at a temperature of 1573 K, it decreases to 1315 mN∙m−1. As the temperature and titanium content in the alloy increase, a decrease in the contact angle is observed. The highest values of contact angles were recorded in the case of contact of the liquid alloy with graphite. For an alloy containing 0.1% wt. Ti at a temperature of 1373 K, the contact angle reaches 132°, while at a temperature of 1573 K, it decreases to 128°. For an alloy containing 1.5% wt. Ti, the values of contact angles are 100° and 96°, respectively. However, the contact angles have the lowest values for magnesium oxide. In the case of a temperature of 1573 K and an alloy containing 1.5% wt. Ti, the contact angle reaches 49°. Such a significant impact of titanium content on the contact angles may be due to its high affinity for oxygen (contact with a substrate made of Al2O3 and MgO and its reactivity with carbon (contact with graphite). [ABSTRACT FROM AUTHOR]

Experimental studies of the high-temperature interaction of a molten Mg-10Ca alloy (10 wt% Ca) with steel substrates were performed, for the first time, using the sessile drop method combined with non-contact heating and capillary purification procedure. The investigations were carried out under isothermal conditions at a temperature of 700 °C in two different flowing gas atmospheres: (i) a pure Ar and (ii) a mixture of Ar + 5 wt% H2. The high-resolution side-view images of Mg-10Ca/steel couples collected during the experiments were used to determine the contact angle values (θ) formed between the alloy drop and steel substrates. In both atmospheres, under the experimental conditions used, liquid Mg-10Ca alloy exhibited non-wetting behavior on steel substrates: after 180 s of dropping alloy from a graphite capillary, the average contact angle value in the Ar atmosphere was θav = 120°, which was slightly higher than that for the test performed in the Ar + 5 wt% H2 atmosphere, where θav = 114°. The microstructure of the solidified couples was analyzed by scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS). The SEM/EDS analysis revealed interfacial discontinuities throughout the cross-sectioned couples and a lack of permanent bonding between the alloy drop and substrates. Moreover, neither new phases nor mass transfer through the drop/substrate interface were noted. The non-wetting and weak bonding between the alloy drops and the steel substrates is consistent with the Mg–Fe and Ca–Fe phase diagrams, i.e., the non-reactive nature of the Mg-10Ca/steel couples, since at the testing temperature, Fe does not form any compounds with both Mg and Ca, and it does not dissolve in liquid Mg. [ABSTRACT FROM AUTHOR]

The high-temperature interaction between molten gray cast iron and Ti + C substrates that are composed of titanium and graphite powders was investigated by the sessile drop method combined with the non-contact heating of an alloy/substrate couple to a test temperature of 1330 °C in an inert gas atmosphere (argon). During the high-temperature testing, the images of the couple were recorded by a high-speed high-resolution CCD camera and used for estimating the values of the contact angles over time. An analysis of the wettability kinetics of the different Ti + C substrates by molten cast iron as well as a detailed structural characterization of the solidified couples with the help of light microscopy, electron microscopy (SEM, TEM), X-ray diffraction, and energy-dispersive X-ray spectroscopy have allowed us to explain the mechanism of high-temperature interaction in the selected couples. It was evidenced that the good wetting and fast infiltration of all of the examined substrates with the selected alloy had a reactive nature due to the dissolution of the Ti and graphite in the molten alloy (dissolutive wetting) and the reactively formed wettable TiC phase. These high-temperature phenomena contributed to the formation of three metal-infiltrated zones with different amounts and distributions of TiC particles in the Fe-based matrix. [ABSTRACT FROM AUTHOR]

The wettability of black silicon (b-Si) layers formed by reactive ion etching, metal-assisted chemical etching, and laser-induced etching has been studied. The wetting contact angles of the prepared samples with deionized water, glycerol, diiodomethane, and ethylene glycol were determined. It has been shown that the silicon oxide surface film and the enlargement area factor of b-Si layers have a significant influence on their wettability, varying from hydrophilic to hydrophobic properties. [ABSTRACT FROM AUTHOR]

The study involved measurements of surface tension of liquid binary copper-titanium alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy–refractory material-gaseous phase system wettability using usual refractory materials, i.e., graphite, aluminum oxide and magnesium oxide. The experiments were performed with the use of the sessile drop method and a high-temperature microscope coupled with a camera and a computer. The aim of this study was to determine the influence of titanium content in the Cu-Ti alloy on the surface tension and contact angle at the interface between the liquid alloy and the refractory material. The influence of temperature on these parameters was also examined. The tests were carried out for copper-titanium alloys with a maximum content of 1.5% wt. Ti, in the temperature range of 1373 to 1573 K. The test results indicate that as the titanium content in the alloy increases, its surface tension increases slightly. However, an increase in temperature causes a decrease in the surface tension of the alloys. In the case of an alloy containing 1.5% wt. Ti, surface tension at a temperature of 1373 K reaches 1351 mN∙m−1, and at a temperature of 1573 K, it decreases to 1315 mN∙m−1. As the temperature and titanium content in the alloy increase, a decrease in the contact angle is observed. The highest values of contact angles were recorded in the case of contact of the liquid alloy with graphite. For an alloy containing 0.1% wt. Ti at a temperature of 1373 K, the contact angle reaches 132°, while at a temperature of 1573 K, it decreases to 128°. For an alloy containing 1.5% wt. Ti, the values of contact angles are 100° and 96°, respectively. However, the contact angles have the lowest values for magnesium oxide. In the case of a temperature of 1573 K and an alloy containing 1.5% wt. Ti, the contact angle reaches 49°. Such a significant impact of titanium content on the contact angles may be due to its high affinity for oxygen (contact with a substrate made of Al2O3 and MgO and its reactivity with carbon (contact with graphite).

For the first time, experimental data on the high-temperature interaction of liquid Mg with pure Ag are presented. The study was performed by the sessile drop method and capillary purification procedure. The test was carried out under isothermal conditions at 720 °C in a protective atmosphere of Ar + 5 wt.% H2. The solidified couple was subjected to detailed microstructural observations by scanning electron microscopy (SEM) coupled with energy-dispersive x-ray spectroscopy (EDS). Under the used conditions, immediately after contact with the Ag substrate, liquid Mg drop showed a good wetting (θ0 ~ 65°) followed by fast spreading over the substrate in subsecond time to form the final contact angle of θf ~ 31°.SEM/EDS analysis showed that θf is apparent because of a deep crater (200 μm) formed in the substrate under the drop by the dissolution of Ag in liquid Mg. SEM/EDS observations of complex structural transformations in the Mg/Ag couple due to high-temperature contact and subsequent cooling are in good agreement with the Ag-Mg phase diagram. Besides substrate dissolution, the interaction between liquid Mg and solid Ag at 720 °C is accompanied with the alloying of the Mg drop with Ag and the formation of a continuous layer of the β-AgMg phase at the Mg/Ag interface. During cooling, the chemical composition of the Mg(Ag) drop continuously changes, and this process is followed by the formation of the β-AgMg phase by secondary precipitation from Ag-saturated liquid, a partial transformation of the β-AgMg to ε′-Ag17Mg54 phase by peritectic reaction, followed by the solid-state transformation of the ε′-phase to the ε-AgMg3 phase, and finally, the solidification of residual liquid in the form of the two-phase eutectic mixture of AgMg4 + (Mg). The results obtained suggest that a very good wetting and fast spreading observed experimentally for the Mg/Ag couple is caused by high reactivity between liquid Mg and Ag substrate leading to the combined effect of two reactive wetting mechanisms, i.e. through dissolutive wetting and wetting through the formation of the interfacial reaction product (β-phase). [ABSTRACT FROM AUTHOR]

In this paper examinations of high-temperature wetting tests of 3 systems of liquid alloy – cast iron in contact with ceramic materials: magnesia ceramics in combination with natural graphite were presented. After wettability testing, the microscopic observations of the morphology of the sample surface and the cross-section microstructure with the chemical composition in micro-areas were examined. One of the objective of this work was also to verify whether the graphite content would affect the wettability of the magnesia ceramics. The study of high-temperature wetting kinetics of the liquid alloy in contact with the ceramic material, by the "sessile drop" method with capillary purification (CP) procedure was conducted. Under the test conditions, at a temperature of 1450°C and time 15 minutes, all 3 experimental systems showed a non-wetting behaviour. The average contact angle for the system with cast iron drop on magnesia ceramics was 140°, on magnesia ceramics with 10 parts per weight of graphite was 137° and on magnesia ceramics with 30 parts per weight of graphite - 139°. Microscopic observations revealed that in the case of the sample consisting of the cast iron drop on the substrate with magnesia ceramics, the formation of fine separations was not observed, unlike the systems with the substrate with magnesia ceramics and the addition of natural graphite. Numerous, fine droplets accumulate on the graphite flakes and consist mainly of Si as well as Fe and O. On the other hand, the rough MgO grains have a gray, matt surface, without fine separations. The conducted observations indicate the mechanical nature of the bonding - liquid metal penetrates into the pores of the rough ceramics of the substrate. However, in the case of systems of cast iron drop with magnesia ceramics and addition of graphite, probably the adhesive connection and the physical attraction of elements derived from cast iron drop with the flake graphite appeared as well.

The wetting behavior of liquid magnesium drop on pure tungsten substrates was investigated, for the first time, with the sessile drop method combined with non-contact heating and capillary purification of a Mg drop from a native oxide film. A specially designed apparatus dedicated to the investigation of the high-temperature interaction of dissimilar materials was used. The comparative experiments were performed under isothermal conditions at temperatures of 700 °C and 740 °C using two atmospheres: Ar + 5 wt.% H2 and pure Ar, respectively. During high-temperature tests for 180 s, the images of the Mg/W couples were recorded with CCD cameras (57 fps) from two directions of observation. The solidified drop/substrate couples were subjected to structural characterization using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Under the applied measurement conditions, liquid Mg revealed non-wetting behavior on W substrates (a contact angle θ > 90°). The average value of the contact angle under the flowing Ar atmosphere at 740 °C was θav = 115°, whereas it was higher under the flowing Ar + 5 wt.%. H2 atmosphere at a lower temperature of 700 °C, showing θav = 122°. Independently on employed atmosphere and temperature, SEM + EDS analysis of solidified sessile drop couples did not display any new phases and mass transfer between the Mg drop and the W substrate, whereas the presence of discontinuities at the Mg/W interface of cross-sectioned couples were well-distinguished. Non-wetting and a lack of permanent bonding between the Mg drop and W substrates have a good agreement with the Mg–W phase diagram calculated with the help of FactSage software and FTlite database, i.e., the non-reactive nature of the Mg/W couple because W does not dissolve in liquid Mg and it does not form any compounds with Mg. These findings allow for the recommendation of tungsten as a suitable refractory material for long-time contact with liquid Mg in different container-assisted methods of materials characterization as well as in liquid-assisted processing of Mg components. [ABSTRACT FROM AUTHOR]

In this paper examinations of high-temperature wetting tests of 3 systems of liquid alloy – cast iron in contact with ceramic materials: magnesia ceramics in combination with natural graphite were presented. After wettability testing, the microscopic observations of the morphology of the sample surface and the cross-section microstructure with the chemical composition in micro-areas were examined. One of the objective of this work was also to verify whether the graphite content would affect the wettability of the magnesia ceramics. The study of high-temperature wetting kinetics of the liquid alloy in contact with the ceramic material, by the "sessile drop" method with capillary purification (CP) procedure was conducted. Under the test conditions, at a temperature of 1450°C and time 15 minutes, all 3 experimental systems showed a non-wetting behaviour. The average contact angle for the system with cast iron drop on magnesia ceramics was 140°, on magnesia ceramics with 10 parts per weight of graphite was 137° and on magnesia ceramics with 30 parts per weight of graphite - 139°. Microscopic observations revealed that in the case of the sample consisting of the cast iron drop on the substrate with magnesia ceramics, the formation of fine separations was not observed, unlike the systems with the substrate with magnesia ceramics and the addition of natural graphite. Numerous, fine droplets accumulate on the graphite flakes and consist mainly of Si as well as Fe and O. On the other hand, the rough MgO grains have a gray, matt surface, without fine separations. The conducted observations indicate the mechanical nature of the bonding - liquid metal penetrates into the pores of the rough ceramics of the substrate. However, in the case of systems of cast iron drop with magnesia ceramics and addition of graphite, probably the adhesive connection and the physical attraction of elements derived from cast iron drop with the flake graphite appeared as well. [ABSTRACT FROM AUTHOR]

High temperature behavior of three compacted graphite iron (CGI) alloys on polycrystalline alumina substrates (99.7%, poro­sity

The wetting behavior of liquid magnesium drop on pure tungsten substrates was investigated, for the first time, with the sessile drop method combined with non-contact heating and capillary purification of a Mg drop from a native oxide film. A specially designed apparatus dedicated to the investigation of the high-temperature interaction of dissimilar materials was used. The comparative experiments were performed under isothermal conditions at temperatures of 700 °C and 740 °C using two atmospheres: Ar + 5 wt.% H2 and pure Ar, respectively. During high-temperature tests for 180 s, the images of the Mg/W couples were recorded with CCD cameras (57 fps) from two directions of observation. The solidified drop/substrate couples were subjected to structural characterization using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Under the applied measurement conditions, liquid Mg revealed non-wetting behavior on W substrates (a contact angle θ > 90°). The average value of the contact angle under the flowing Ar atmosphere at 740 °C was θav = 115°, whereas it was higher under the flowing Ar + 5 wt.%. H2 atmosphere at a lower temperature of 700 °C, showing θav = 122°. Independently on employed atmosphere and temperature, SEM + EDS analysis of solidified sessile drop couples did not display any new phases and mass transfer between the Mg drop and the W substrate, whereas the presence of discontinuities at the Mg/W interface of cross-sectioned couples were well-distinguished. Non-wetting and a lack of permanent bonding between the Mg drop and W substrates have a good agreement with the Mg–W phase diagram calculated with the help of FactSage software and FTlite database, i.e., the non-reactive nature of the Mg/W couple because W does not dissolve in liquid Mg and it does not form any compounds with Mg. These findings allow for the recommendation of tungsten as a suitable refractory material for long-time contact with liquid Mg in different container-assisted methods of materials characterization as well as in liquid-assisted processing of Mg components.

The interaction between inks and substrates is critical during printing. Adhesion of the ink film is determined by the reciprocal interactions of polar and nonpolar (dispersive) components between polymer films and inks. The greater the similarity between the polar and dispersive components of inks, coating and substrates, the better the wetting and adhesion on the surface of printing substrate. Various liquid materials in printing such as inks, varnishes, lacquers, and adhesives contain high ratios of water. The highly polar nature of water makes the interaction of these materials unsuitable with predominantly disperse polymer surfaces. Some films with polyolefin structure, especially polypropylene, and polyethylene, are nonpolar and cannot form strong bonds with ink, varnish, or lacquer coatings due to their chemical structure. Increasing surface energy components overcomes the poor wetting and adhesion on polymer surfaces. In this review, the topics of water contact angle measurement and determination of surface energy, surface tension, and using sessile drop method for the wettability and ink adhesion of polymer films are surveyed. Information on structural and chemical processes was given that assists in obtaining wettable film surfaces. Recommendations were made for good adhesion and printability based on surface treatment methods and ink modification. [ABSTRACT FROM AUTHOR]

High temperature behavior of three compacted graphite iron (CGi) alloys on polycrystalline alumina substrates (99.7%, porosity <3%) were examined by the sessile drop method combined with classical contact heating procedure in flowing Ar. High-speed high-resolution CCd camera was used for continuous recording of the CGi/Al2o3 couples during melting alloy, heating to and holding the couples at the test temperature of 1450°C for 15 min and their subsequent cooling. The comparative studies were made with conventional CGi (in wt.%: 3.70 C, 2.30 Si, 0.44 Mn, 0.054 P, 0.017 Mg, 0.015 S) and two alloys additionally containing the same amounts of 0.25 Mo, 0.1 V, 0.045 Sn and 0.032 Sb with different concentrations of Mg + Cu additions, i.e. 0.01Mg + 0.33Cu and 0.02Mg + 0.83Cu. All three CGi alloys demonstrated non-wetting behavior on the Al2o3 substrates while the contact angle values slightly decreased with increase of the Mg + Cu content in the alloy, i.e. 131° (unalloyed CGi), 130° (0.01Mg + 0.33Cu) and 125° (0.02Mg + 0.83Cu). Structural characterization of solidified couples by light microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed: 1) heterogeneous nucleation of discontinuous graphite layer at the drop-side interfaces and on the surface of the drops; 2) reactively formed Mg-rich oxide layer at the substrate-side interface; 3) the formation of satellite droplets on the surface of the drops during their solidification; 4) degeneration of initially compacted graphite to lamellar graphite after remelting and subsequent solidification of the drops, particularly in their surface layer. [ABSTRACT FROM AUTHOR]

The results of investigating the wettability of commercial multi-walled carbon nanotubes (MWCNTs) Taunit-MD under irradiation with 120-keV Ar+ ions with various fluences are presented. The structure of the irradiated MWCNTs is investigated using Raman spectroscopy, scanning electron microscopy, and X-ray microanalysis of the samples. The dependences of the average diameter of the MWCNTs, the O2 concentration, and defects in the MWCNT samples on the irradiation fluence, as well as their effect on the wettability with distilled water, ethylene glycol, and cyclohexane are considered. The possibility and prospects of using ion-beam modification methods for controlled variation of the wettability with the aim of creating a MWCNT coating, which is hydrophobic or hydrophilic to various types of liquids, are discussed. [ABSTRACT FROM AUTHOR]

• Experimentally investigated high-temperature interaction of liquid Mg with solid Cu. • Wettability of liquid magnesium on the solid metallic copper. • A very good wetting and spreading of liquid magnesium on solid copper (θ less than 90°). • The SEM/TEM/EDS analysis of the Mg/Cu couple after sessile drop test. For the first time, experimental results of the high-temperature interaction of liquid magnesium with pure copper are presented. The investigation was performed using the sessile drop method and capillary purification procedure allowing both non-contact heating of the Mg/Cu couple and in situ cleaning of the Mg drop from a native oxide film. The test was done under isothermal conditions at 710 °C in a protective atmosphere, which was a mixture of Ar + 5 wt% H 2. The images of the Mg/Cu couple collected during the high-temperature measurements were used to determine the time-dependent values of the contact angle (θ) formed between the liquid magnesium drop and the copper substrate. The solidified couple was subjected to detailed microstructural observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), both coupled with energy-dispersive X-ray spectroscopy (EDS). Under the applied measurement conditions, immediately after contact with the Cu substrate, the liquid Mg drop showed a very good wetting (θ 0 ∼ 22°), followed by rapid spreading over the substrate, forming a final contact angle θ f ∼ 11°. However, SEM/EDS analysis revealed that θ f is an apparent angle due to the deep crater (∼200 μm) formed in the substrate under the Mg drop by the dissolution of Cu in liquid Mg. The comparative SEM/TEM/EDS analysis suggests that good wetting and rapid spreading in the Mg/Cu couple are dominated by the reactive wetting mechanism due to the dissolution of the Cu substrate in the liquid Mg drop and its saturation with a high amount of dissolved Cu. Consequently, the microstructure of the solidified drop was composed of large Cu-rich primary MgCu 2 crystals surrounded with a two-phase eutectic mixture (MgCu 2 + Mg 2 Cu) formed at the final stage of cooling. In addition, the MgCu 2 phase was also nucleated and grown at the Mg/Cu interface to form a continuous layer. [ABSTRACT FROM AUTHOR]

The reactive wetting behaviors of molten Zn-Al-Mg alloys on MnO- and amorphous (a-) SiO2-covered steel sheets were investigated by the sessile drop method, as a function of the Al and Mg contents in the alloys. The sessile drop tests were carried out at 460 °C and the variation in the contact angles (θc) of alloys containing 0.2-2.5 wt% Al and 0-3.0 wt% Mg was monitored for 20 s. For all the alloys, the MnO-covered steel substrate exhibited reactive wetting whereas the a-SiO2-covered steel exhibited nonreactive, nonwetting (θc > 90°) behavior. The MnO layer was rapidly removed by Al and Mg contained in the alloys. The wetting of the MnO-covered steel sheet significantly improved upon increasing the Mg content but decreased upon increasing the Al content, indicating that the surface tension of the alloy droplet is the main factor controlling its wettability. Although the reactions of Al and Mg in molten alloys with the a-SiO2 layer were found to be sluggish, the wettability of Zn-Al-Mg alloys on the a-SiO2 layer improved upon increasing the Al and Mg contents. These results suggest that the wetting of advanced high-strength steel sheets, the surface oxide layer of which consists of a mixture of MnO and SiO2, with Zn-Al-Mg alloys could be most effectively improved by increasing the Mg content of the alloys. [ABSTRACT FROM AUTHOR]

Research of the last years pointed out that most soils are neither completely hydrophilic nor hydrophobic, but exhibit a subcritical level of water repellency (i.e. contact angle, CA > 0° and < 90°). Soil water repellency (SWR) is mainly caused by organic compounds of different origin and structure, showing the relevance of biofilms and organic coatings present at many particle surfaces. Despite the importance of SWR for hydraulic processes like preferential flow phenomena, generation of heterogeneous moisture patterns, or surface run-off generation, detailed investigations on the spatial variability of SWR at various scales have rarely been carried out. We introduce a new and easy-to-apply operation for measuring the spatial distribution of SWR using a modified sessile drop method for direct optical assessment of CA at a small scale. The specific objectives of this paper are to apply a sampling and preparation technique that preserves the original spatial arrangement of soil particles and to characterize soil wettability in terms of CA at a high spatial resolution. Results revealed that the sampling and preparation technique allows determination of CA at the millimeter scale using droplets of 1 μL volume. Direct measurement on grain surfaces of the sand fraction is possible for grain sizes > 300 μm using drop volumes down to 0.1 μL. Geostatistical evaluation showed that the measurement grid scale is below the range of spatial dependency for droplets of 1 μL volume, but not for measurements on single grains (pure nugget effect). Results show further that the small-scale differences in wettability, especially for CA < 90°, cannot be detected by the conventional WDPT test. From these findings it can be concluded that the proposed technique allows the identification of small-scale variations in wettability that may promote the formation of heterogeneous flow fields and moisture patterns in soil under unsaturated conditions.

The wettablity at a liquid of pure-Al or Al-Mg alloys/ Al2O3 interface wasevaluated by the sessile drop method at 700oC and with a vacuum pressure of10-4Pa. The value of contact angle varies (decreases) with time of contact withAl2O3 substrate. The reduction in θ of the Al-Mg alloy was proportional to thereduction in surface tension γlv of Al, and to reactions that took place at the Alalloy/Al2O3 interface.

Electrochemical machining is applied not only in die and mold fabrication, but also in the finishing process for parts manufacturing. Especially when ECM is used in finishing purposes, surface properties become more important. In this study, the wettability which is one of the surface properties was focused on and discussed. The sessile drop method and the contact angle are used to evaluate the wettability. In order to measure the contact angle based on JIS R 3257, how the contact angle changes within the allowable measurement range that JIS prescribed was experimentally examined. It was found that the contact angle changes temporally and quantitatively within the JIS allowable extent. In order to measure contact angles correctly, the measurement conditions under which the range is stricter than the JIS range was investigated and discussed. After the measurement conditions were decided, contact angles of stainless SUS304 surfaces that machined with ECM were experimentally investigated. In order to clarify the relationship between ECM conditions and the wettability of the machined surface, the change in the contact angle when varying the kind of electrolyte and the current density was examined. It was found that the surfaces machined with ECM using NaNO 3 solution as electrolyte with lower current density has a lower contact angle. When the current density increases, there appears proportional relation between the current density and the contact angle. [ABSTRACT FROM AUTHOR]

The sessile drop method is an easy and fast method used to measure the contact angle between solids and liquids. The value of the contact angle is used in surface characterization, in particular the wettability of solid surfaces by the liquid and to calculate the surface free energy. In this work, we study the effects of the volume of the drop placed on the surface, the elapsed time between drop placing and measurement and the cleaning of the substrate (not cleaning, washed with ethanol or washed with acetone) in the value of the contact angle on Ti6Al4 V and AISI 316 stainless steel. We found that drop asymmetry is a very important parameter that must be considered in CA measurements. Anasymmetry parameter used to qualify the drop asymmetry is proposed. It was also found that the degree of cleanliness produces dispersion in the contact angle values; on the other hand no differences were found between cleaning with ethanol or acetone. CA decreases with time and increases slightly with decreasing droplet volume. [ABSTRACT FROM AUTHOR]

The study involved measurements of surface tension of liquid binary copper-bismuth alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy - refractory material - gaseous phase system wettability using usual refractory materials, i.e. aluminium oxide, magnesium oxide and graphite. The experiments were performed with the use of sessile drop method and a high-temperature microscope coupled with a camera and a computer was utilised. [ABSTRACT FROM AUTHOR]

Abstract: The wettability and spreading kinetics of Zr-based alloy melt on W substrate were evaluated using the modified sessile drop method under ultrahigh vacuum. The alloy melt wets the substrate well and the spreading kinetics indicates that drop spreading is mainly controlled by the viscous friction. The drop spreads rapidly and the spreading follows the hydrodynamic model and Jiang's empirical formula. The spreading of the drop shows little interaction with the precursor film, which is generated by diffusion. After the initial incubation period, the equilibrium contact angle stabilizes at about 29°, and the precursor film spreads linearly with the square root of time. [Copyright &y& Elsevier]

Abstract: Edible films have been extensively studied with the aim to find an adequate formulation that allows improving food quality and safety. Both wettability and water-barrier properties are two important parameters that must be considered for an adequate design of edible coatings. The aim of this work was to measure the contact-angle of film solution based on carboxymethylcellulose (CMC) with murta leaf (Ugni molinae Turcz) extract to estimate the wettability on apple and quince skins and measure the water vapor permeability (WVP) of films. The results show that murta leaves extract did not affect the contact angle and wettability measured on the fruits surface. However, differences were obtained between apple and quince skin which can be explained because the dispersive component of surface tension of quince skin was lower than apple skin. The WVP was not affected by murta leaves extract incorporation. This allows concluding that the film properties assayed were not modified by the incorporation of murta leaves extract ecotype 14-4. [Copyright &y& Elsevier]

The paper addresses the application of a sessile drop method for the study of surface quality of thermoplastic polymer materials—polystyrene and polymethyl methacrylate—upon edge cutting machining. A correlation has been found between the thermal-physical state of their surface layer and the surface wettability. The method is demonstrated to be suitable for the assessment of thermodynamic stability of the surface layer structure of polymers during finishing operations in the manufacture of optical products. [ABSTRACT FROM AUTHOR]

The phenomena influencing the properties of plasma sprayed ceramic-metal composite (cermet) deposits were examined. For that purpose, cermet deposits were developed by co-spraying alumina and austenitic stainless steel powders and were compared with those fabricated by spraying these powders individually. A set of particle injection and plasma spray parameters were determined by optimizing deposition efficiency of sprayed powders. The properties of the fabricated composite deposits were only partially dependent on the inherent properties of the parent materials and other factors had more dominating influence. Beside other factors, in-flight metallic particle oxidation and ceramic-metal wetting behavior were found to be the major phenomena controlling deposit properties. The in-flight particle oxidation, contributing up to 43% of the total oxide in metallic deposits, resulted in higher hardness and elastic modulus values of stainless steel deposits. The formed oxide could assist in improving the wetting behavior of stainless steel-alumina system, studied by sessile drop method. In non-wetting conditions, extensively fragmented stainless steel splats were collected on predeposited alumina causing poor interlamellar contacts and inferior deposit integrity and mechanical properties. [ABSTRACT FROM AUTHOR]

Understanding the atomic-level phenomena occurring upon the wetting of graphene-coated Cu with liquid Ag is pivotal for the description of the wetting phenomenon and the role of graphene as a diffusion barrier. We have performed molecular dynamics (MD) simulations and confronted with our present experimental results to characterize wetting behavior of graphene coated Cu surfaces. Perfect and defected graphene layers covering Cu surface were wetted with liquid Ag droplet at 1273 K. Structural and topological aspects are discussed to characterize structure of the liquid Ag droplet and a product of wetting reaction occurring on Cu/Gn and Cu/Gndef substrates, also including perfect graphene layer and a pure Cu surface. The obtained results reveal the importance of defects in graphene structure, which play a key role in wetting mechanism and the formation of AgCu alloy. As a consequence, we observe a change of the wetting behavior and topology of both bulk and adsorbed Ag atoms by using Voronoi analysis (VA). Despite the differences in time scale, atomistic simulations allowed us to catch the early stages of wetting, which are important for explaining the final stage of wetting delivered from experiment. Our findings reveal also graphene translucency to metal-metal interactions, observed in previous papers. [ABSTRACT FROM AUTHOR]