Search

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]

[Display omitted] • A standardized contact angle measurement method for porous powder materials. • Effect of laminating treatment on structure and wettability of PCN is investigated in detail. • The contact angle data is stable and reproducible. • Oil contact angle data of PCN are reported explicitly. • The method provided can solve the dilemma of PCN wettability data confusion. The wettability of polymeric carbon nitride (PCN) is an important surface chemical factor affecting its catalytic and separation performance. However, due to the amphipathic characteristics of hydrophilic/lipophilic and porous powder properties, the contact angle (CA) of PCN measured by the common sessile drop method will be interfered by the substrate, resulting in randomness of the results. Herein, the pristine PCNs obtained by thermal polycondensation of different precursors in air or nitrogen atmosphere were used as the wettability research object. The CA of the PCNs was measured by a modified sessile drop method after the traditional powders were replaced by pressed-tablet samples. The influence of sample mass and applied pressure on specific surface area, pore volume, surface morphology and CA of the pressed-tablet samples was investigated carefully, and the optimal experimental conditions were determined. When the sample mass was 0.15 g and the applied pressure was 10 MPa, the measured water CA of PCNs was between 27 ∼ 34°, and the diiodomethane CA is between 24 ∼ 29°. The measurement results showed considerable stability and reproducibility. This improved CA measurement method provides a simple and standardized way to accurately explore the surface chemistry of PCN, and has the potential to be applied to other hydrophilic and/or oleophilic porous powder materials. [ABSTRACT FROM AUTHOR]

High-entropy silicide (HES) coatings are a promising solution to the problem of poor oxidation resistance of metallic refractory alloys. However, their practical development is still in the early stages. For the first time, this study evaluates the feasibility of synthesizing complex concentrated silicide coatings using a reactive melt infiltration approach. For this purpose, a sessile drop experiment was carried out in which a binary eutectic silicon‑boron alloy (Si 8B at.%) was subjected to contact heating with the MoNbTaW refractory high entropy alloy (RHEA) substrate at temperatures up to 1450 °C. After the high-temperature test, the solidified couple was characterized by X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, electron backscatter diffraction systems, and microhardness techniques. The coating had an average thickness of 75 μm and was composed of different layers, including a primary MSi 2 layer, a transition MSi 2 + M 5 Si 3 silicide layer, and M 5 Si 3 silicides (M = metal). Additionally, borosilicides and boride particles were dispersed throughout the layers. However, future research should prioritize refining process parameters to eliminate porosity and improve the integrity of the coating layer. [Display omitted] • First proof of concept of synthesizing complex concentrated silicide coatings via liquid-assisted method. • Successfully synthesized multilayer silicide-based coating on MoNbTaW alloy using molten Si-B alloy. • Showcases silicide-based coatings can be produced in one-step under pressure-less conditions without chemical activators. • Formation of a multilayered coating, with MSi 2 and M 5 Si 3 as the main phases plus minor quantities borides and borosilicides. [ABSTRACT FROM AUTHOR]

• Wetting experiment using capillary purification procedure in sessile drop method ensured the in-situ cleaning of Al drop from native oxide. • Al drop showed good wetting at 720 °C on the deformed steel substrate - contact angle decreased from 35° to 7° after 100 s. • The interface zone was of dual-morphology: grains of Al5Fe2 phase penetrating steel substrate and θ-Al13Fe4 phase growing towards Al drop. • The Al5Fe2 phase formed the long colonies of similarly oriented grains, while the θ-Al13Fe4 phase was of needle shape morphology. • Dissolution of steel substrate and formation of the thick product layer beneath the drop were responsible for good wetting behaviour. The high-temperature liquid Al - solid S355J2N steel interaction was studied using a modified wettability test. A sessile drop method with a capillary purification procedure was employed for the first time, involving non-contact aluminium isothermal heating followed by the dropping of a pure liquid Al drop onto the severely deformed steel substrate and isothermal contact heating of Al with steel. The calculated contact angles and wetting kinetics curves demonstrated a good spreading and wetting of the investigated system. Scanning electron microscopy investigations played an important role in interpretation of the microstructural characteristics of the specimen, especially those located at the drop/substrate interface. The electron backscattered diffraction measurements allowed to characterize the microstructure of the interface zone to obtain more detailed information about the grain size, type of the intermetallic phases: θ-Al 13 Fe 4 , Fe 2 Al 5 , FCC Al and ferrite and their distribution in the neighborhood of the interface zone. These intermetallics were also confirmed via transmission electron microscopy studies coupled with energy-dispersive X-ray spectroscopy analysis of the drop/substrate interface. Research findings provide valuable insights into the liquid Al and steel interaction during the explosive welding process, where the local melting of metal takes place at the interface of colliding plates, strongly deformed due to the collision. [ABSTRACT FROM AUTHOR]

The corrosion of refractory is generally related to the wetting between slag and refractory. Investigating the wetting and corrosion characteristics of refractory by molten slag has a positive significance to elucidating the corrosion mechanism and understanding the slag resistance. In this work, the apparent contact angles of the CaO–Al 2 O 3 –SiO 2 –(MgO) molten slags on microporous magnesia aggregate (MM) and fused magnesia (FM) substrates were respectively measured by sessile drop method under Ar atmosphere at 1550 °C. The dissolution of the MM substrate and the slag penetration behavior were investigated by combining the theoretical calculation of the FactSage thermodynamic software with the examination of SEM-EDS. The results show that MM substrate had a better slag resistance than FM substrate. The final apparent contact angles (θ f) of slags with the CaO/SiO 2 values of 3, 5 and 11 on MM substrate were 15.8°, 21.4°, and 9.2°, respectively, and that with the MgO content of 3, 6 and 9 mass% were 11.1°, 14.2°, and 52.5°, respectively. The larger the CaO/SiO 2 value of the slag, the more beneficial it was to slowing down the dissolution of MM and FM substrates; the original slag with MgO was also beneficial to lessening the dissolution of the MM substrate, which was better than that with a high CaO/SiO 2 value. The formation of MA could inhibit the slag from penetrating. In addition, for slags with different CaO/SiO 2 values, the effects of surface tension and viscosity on slag penetration were more significant than that of contact angle; for slags with different MgO contents, the effect of contact angle on slag penetration was more significant than those of surface tension and viscosity. [ABSTRACT FROM AUTHOR]

The wetting and corrosion behavior of the corundum substrate anode by CaO–SiO 2 –MgO molten slag was investigated via the joint application of the sessile drop method with applied voltage and SEM-EDS technique. The slag drop exhibited a good wettability on the corundum substrate. The apparent contact angle at zero voltage slightly exceeded that at a 1 V applied voltage but was lower than those at 1.5 V and 2 V ones. Low applied voltage of 1 V had little effect on the corundum substrate's direct dissolution corrosion processes; high ones of not less than 1.5 V caused the electrode reaction to occur. The stirring effect of O 2 bubbles from the anode reaction aggravated the substrate's direct dissolution and physical stripping. It was found that the applied voltage could inhibit the slag penetration, and the apparent contact angle had no obvious relation with the direct dissolution thickness and penetration depth. A thin but almost continuous MgO⋅Al 2 O 3 (MA) layer could form at the slag/substrate interface at the applied voltage of 1.5 V. These results indicate the positive effect of applied voltage on the distribution of interfacial products and the molten slag penetration in reducing the corrosion of corundum anode under certain conditions. However, when the applied voltage was too high, the vigorous electrode reaction could aggravate the direct dissolution and physical stripping of the corundum anode, and damage the continuation of the formed interface product layer with a high melting point. [ABSTRACT FROM AUTHOR]

Maize grain have a high moisture content in the harvest period, and a model to calculate the JKR surface energy between high-humidity maize grains was developed. A system was designed and used to measure the contact angle. The effects of different factors on the JKR surface energy were investigated. The results showed that the JKR surface energy of maize grains increased with increasing moisture content and temperature. The content of crude starch in grains is the main factor that affects the JKR surface energy. The JKR model and no slip model of EDEM were used to simulate the collision of high-humidity maize grains, and the results were compared with the physical tests. The data obtained by the JKR model are compared with those obtained by Young model and OWRK model. The results provide a reference for the calculation of the JKR surface energy of other particles with high moisture content. Unlabelled Image • JKR surface energy of high-humidity maize grain was investigated. • The mathematical model of JKR surface energy was founded. • The effects of different factors on the JKR surface energy of grain were investigated. • JKR surface energy was mostly affected by the content of coarse starch in the grains. [ABSTRACT FROM AUTHOR]

• Experimental assessment of a novel liquid-assisted borosiliconizing process. • A new technological approach for a fabrication of Mo-Si-B materials. • Wetting, spreading and reactivity in Si-B/Mo system. • Reactively formed molybdenum silicides, borosilicides and borides. In this work, we used a sessile drop experiment to assess a feasibility of novel processing design engaging liquid-phase assisted fabrication of multi-phase materials from Mo-Si-B system. For this purpose, binary eutectic silicon-boron alloy (Si-3.2B wt%) was subjected to contact heating with polycrystalline molybdenum substrate at temperature up to 1385 °C. It was in-situ observed that molten Si-3.2B alloy wets and rapidly spreads over the Mo surface. After the high temperature test, the solidified couple was subjected to structural characterization by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction methods. The obtained results revealed that the direct interaction between examined materials under applied testing conditions results in the reactively formed product layer having a thickness of ∼80 µm. The following structural features were recognized starting from the surface side: (I) the main product layer composed of columnar-like MoSi 2 phase and Mo 5 Si 3 phase; (II) an intermediate layer made of MoB and Mo 5 SiB 2 phases. Although these results give the first indication for designing a novel liquid-assisted fabrication method of Mo-Si-B materials, an existence of porosity in the product layer clearly suggests that a further optimization of the process parameters is necessary. [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]

In an ideal unsaturated soil model, the contact angle (CA) is often determined by the sessile drop method (SDM), or assumed without any test. However, both approaches can lead to errors in the model calculation results. In this study, methods that combine models of unsaturated soil with CA measurement methods is presented. The characteristics of soil CA were studied using the sessile drop method (SDM) and the direct observation method (DOB). The results demonstrated that the CA values of soils and CA variation characteristics measured with SDM were significantly different from those measured with DOB. SDM measures the CA of a surface, which is a "plane" formed by many particles, whereas DOB measures the CA between soil particles on a smaller scale. The measurement results of SDM can determine the degree of soil hydrophobicity but may cause large errors when used as a parameter of an ideal unsaturated soil model. The DOB can simulate the natural drying-wetting cycles of soils, and its measurement results are closer to the natural conditions. Using the mean CA as a model parameter is reasonable, except when the CA value is 0. The hysteresis phenomenon caused by using CA hysteresis for the soil-water characteristic curve (SWCC) is likely to overestimate the effect of CA hysteresis on soil water retention behavior. • The contact angle values measured using sessile-drop method were different from direct observation method. • Applying the measurement results of sessile-drop method may cause large calculation errors. • Contact angle hysteresis has little effect on soil water characteristic curve. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to evaluate if bond strength measurements obtained from the Asphalt Bond Strength (ABS) test can be supported by cohesive and adhesive bond strength estimations using surface energy measurements. Surface energy of asphalt binders was obtained from contact angle measurements using Sessile Drop method. By using estimated surface energy of binders and reported values for aggregates, the work of cohesion and work of debonding were calculated and compared to ABS results. Analysis of data shows that ABS results are in agreement with thermodynamics based properties of different asphalt binders. [ABSTRACT FROM AUTHOR]

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 dynamics of a receding contact line of water drops on polymeric substrates (poly(methyl methacrylate), PMMA, and polycarbonate, PC) was studied using the sessile drop method. For smoother substrates, multiple stages were observed: the constant contact radius (CCR) mode, the constant contact angle (CCA) mode, and the mixed mode. In the CCA mode, the contact angle (CA) remained nearly constant and the receding dynamic CA could be identified. The relation between the receding dynamic CA and the withdrawal rate was experimentally determined, and the receding dynamic CA was found to decrease with increasing liquid withdrawal rate. A decrease of 5–10° was found for PMMA substrates, whereas a decrease of 10–20° was observed for PC substrates for commonly applied liquid withdrawal rates. Our results quantitatively agree with those obtained by the capillary tube method and the plate method, and we demonstrated that the sessile drop method can serve as an alternative method for studying contact line dynamics. In addition, for the rough PC substrates, the CCA mode was absent and the receding dynamic CA could not be identified. Therefore, we demonstrated that on rough polymeric substrates, the sessile drop method must be used with caution, and complete CA relaxation profiles and liquid withdrawal rates should be reported. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the experimental performance of a new testing device designed for investigating the high temperature properties of molten Mg is presented. The newly developed device allows examining high temperature wetting behavior and thermophysical properties of molten Mg (and Mg alloys) by using various experimental procedures (e.g. classical sessile drop, pendant drop, dispensed drop and drop sucking). High temperature wettability tests at temperatures up to 1000 °C in an inert gas atmosphere or under high vacuum (up to 10−7 hPa) are now possible. It has been documented that the application of the classical sessile drop method combined with a capillary purification procedure successfully eliminates the problem of magnesium oxidation that traditionally affects obtained results. Selected examples of high temperature experiments carried out for molten Mg in contact with various refractories are presented in order to show a wide range of analytical possibilities of the new device. The results obtained by using the new device are important from both a high theoretical and practical perspective regarding liquid phase assisted fabrication and processing of Mg-based alloys and metal-matrix composites. [ABSTRACT FROM AUTHOR]

When hydrophobic particles are employed to prepare self-lubricating electroless composite coatings, they usually require surface modification to improve their wettability. The study focuses on the resultant change in wettability of the MoS 2 particles with an inorganic coating. Al 2 O 3 -coated MoS 2 particles were prepared by using a heterogeneous nucleation process. Then, particle surface morphology and structure were examined by using SEM, EDS and XRD. Contact angle measurements were conducted by using a thin layer wicking technique and a sessile drop method in order to determine the surface free energy components of the bare and the coated MoS 2 particles. Our results showed the MoS 2 particles were successfully coated with an Al 2 O 3 layer, which is an amorphous structure. The decreased water contact angle indicates an enhanced hydrophilicity for the coated particles. This decrease depends more strongly on a significant decrease of a new parameter ratio, γ + /γ − , than on a slight increase in total surface free energy. The surface energy component of the bare MoS 2 is very consistent with that of Talc, and that of the Al 2 O 3 -coated one is very similar to that of alumina, apart from the base component. [ABSTRACT FROM AUTHOR]

Surface Free Energy (SFE) of solids should be calculated using theoretical models. The contact angle (CA) measurement on a surface is considered the most practical way to obtain the SFE. The results of five methods based in the models are compared: the method of Zisman (ZI), the geometric mean (GM), the harmonic mean (HM), the Lifshitz-van der Waals/ Acid-Base (LW/AB) and the equation of state (ES). The SFE calculated with GM, HM and LW/AB methods change with the amount and type of liquid used, however, when water, glycerol and dimethyl sulfoxide are used together the SFE and its dispersive and polar components are similar in value for the three methods. In the case of the ES model the values of SFE change with the liquid used; finally using the ZI method the SFE values are 20% lower than the values of SFE obtained with the other methods. [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]

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: Contact angle measurement is conducted to determine surface hydrophilicity of RO membrane with the intention of predicting membrane performance or fouling potential. Most researchers of membrane technology have used contact angles without considering effective factors for contact angle measurement such as measurement time, drop volume and membrane sample preparation. In fact, significantly different contact angles are reported even on the same RO membrane. In this study, contact angles were measured by the sessile drop method and captive bubble method and were compared with various conditions such as measurement time, drop volume, membrane sample preparation and liquid type in the commercialized RO membranes. As a result, sessile drop method showed unreliable contact angles, which varied dramatically with the preparation conditions. On the other hand, the captive bubble method, which represents conditions closer to the real RO membrane process, showed reproducible contact angles. For the different commercially available RO membranes, similar hydrophilicity was observed. Overall, the captive bubble method appears to be a more adequate method for measuring contact angle of RO membranes. [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]

Abstract: Wetting process and interfacial characteristic of Sn–3.0Ag–0.5Cu have been investigated at temperatures ranging from 503K to 673K on Cu, Ni, stainless steel and quartz, respectively. The reactive wetting behavior of Sn–3.0Ag–0.5Cu melt alloy on Cu and Ni substrates were investigated. Contact angles decrease as exponential decay and equilibrium contact angles decrease between the solder and Cu, Ni substrates monotonously with the temperature increasing. The configuration of the triple line of Sn–3.0Ag–0.5Cu/Cu is discussed by the description of equilibrium. The calculated results based on experimental values of tension balances along each of the three interfaces at this final state show good agreement with theoretical analysis. Intermetallics of the Sn–3.0Ag–0.5Cu/Ni interface are identified as (Cu, Ni)6Sn5 adjacent to the solder and Ni3Sn4 adjacent to the Ni substrate, respectively. The contact angles between Sn–3.0Ag–0.5Cu and quartz, stainless steel substrates were measured to be greater than 90°, which means non-wetting, in the temperature range from 503K to 673K. Liquid–solid interfacial energy between the solder and different substrates are obtained based on the surface tension of molten solder and equilibrium contact angles at different temperatures. These results are of practical interest for composite lead-free solders preparations and joining of Sn–3.0Ag–0.5Cu to various substrates. [Copyright &y& Elsevier]

Abstract: The surface tension and density measurements for Sn–Ag alloys were carried out with the sessile drop method. Seven different compositions were investigated in the range from 0.011 to 0.5 mole fraction of Ag, in a broad range of temperature. With increasing concentrations of Ag, both density and the surface tension are increased. With increasing temperature the density decreases for all of the alloys. A decrease of the surface tension is observed for most of the composition except for the alloy of 0.5 mole fractions of Ag. The obtained results are compared with existing literature data and Butler model calculations and relatively good agreement is observed. [ABSTRACT FROM AUTHOR]

Abstract: The surface tension and density of Sn–Cu liquid alloys were measured with the sessile drop method, in a broad range of temperature. Total of seven compositions were investigated in the range from 0.018 to 0.5 mole fraction of Cu. With increasing concentration of Cu, both density and the surface tension are increased. With increasing temperature the density decreases linearly for all of the compositions. The surface tension exhibits similar behavior for most of the compositions, except for the alloy of 0.5 mole fractions of Cu, in which case the increase of the surface tension is observed. The obtained results are compared with existing literature data and Butler model calculations, and a relatively good agreement is observed. [ABSTRACT FROM AUTHOR]

Abstract: Properties such as thermal and electrical conductivity or the expansion behaviour of silver matrix composites with carbon based inclusions are strongly affected by the contact angle between carbon and silver. In order to promote wetting of carbon, insertion of metallic interlayers such as nickel, cobalt or molybdenum is a feasible approach. This paper presents contact angle measurements done with the sessile drop method on carbon substrates (glassy carbon, polycrystalline graphite) and on pure nickel, cobalt and molybdenum foils. The ability of these interlayer elements to lower the high contact angles of silver on glassy carbon (117°) and polycrystalline graphite (124°) under vacuum conditions was verified. Unlike nickel (30°) and cobalt (26°), molybdenum (107°) nevertheless was not wettable by liquid silver (at 1273K) under vacuum conditions. ToF-SIMS was used to identify oxygen on the surface, causing higher contact angles than expected. After oxide reduction a contact angle of 18° on molybdenum was detected. Furthermore, the influence of carbon diffusion on the contact angle was investigated by gas phase carburization of the metal foils. ToF-SIMS and XRD identified dissolved carbon (Ni, Co) and carbide formation (Mo). However, only nickel and cobalt showed a slight decrease of the contact angle due to carbon uptake. [Copyright &y& Elsevier]

Abstract: The density of binary Ni–Al alloys with aluminum concentration from 0 to 20wt% in liquid state was measured by a modified sessile method (MSDM). It was found that the liquid density of Ni–Al alloys decreases with increasing temperature and Al concentration in the alloys, while the molar volume of liquid Ni–Al binary alloys increases with the increase of temperature and Al concentration. The partial molar volume of Al in liquid Ni–Al binary alloy was calculated approximately. The molar volume of liquid Ni–Al alloy determined in the present work shows a negative deviation from the ideal linear molar volume. [Copyright &y& Elsevier]

Abstract: The results of study on the influence of temperature and iron and antimony on the surface tension of liquid ternary Cu–Fe–Sb systems are presented. The measurements were carried out with the sessile drop method, in a broad range of the alloy additions concentration (Fe and Sb). It was demonstrated that the surface tension varies as a linear function of temperature and concentration of iron. It was also demonstrated that antimony, in examined alloys, shows the properties characteristic of a surface-active substance, significantly reducing the surface tension value. The changes of the surface tensions as a function of concentration of antimony were described with the Szyszkowski''s equation. Composition of surface layer, enriched with an antimony, was determined basing on the model, which used data regarding properties of binary systems. The surface tension values of Cu–Fe–Sb systems was also computed from model and compared with experimental data. A good agreement was obtained. [Copyright &y& Elsevier]

Abstract: The influence of the interfacial energy between the Fe–C melt and basal plane of graphite, γ Gr/L, and the cooling rate on the formation of spheroidal graphite was investigated as a function of the sulfur content in cast iron using the sessile drop method in a He–3% H2 atmosphere. The result showed that the γ Gr/L decreased from 2.62 to 1.48J/m2 with an increase in the sulfur. The corresponding surface energy of the graphite, γ Gr/V, also varied from 1.17 to 0.65J/m2. It is found that the spheroidal graphite is formed when the γ Gr/L is greater than 2.5J/m2, which is the critical interfacial energy of the spheroidal graphite formation. In addition, the cooling rate is also an important factor for producing the spheroidal graphite in the Fe–C alloy. The present study clearly shows that the critical cooling rate is a function of the sulfur content, namely γ Gr/L, in the Fe–C melt. [Copyright &y& Elsevier]

Abstract: Pressure–volume–temperature (PVT) data were studied for ethylene–vinyl alcohol random copolymers (EVOH) and served to determine bulk reduction parameters for the equation-of-state by Flory–Orwoll–Vrij. The compressibility factor as a function of copolymer composition displays positive deviation from additivity. Sessile drop method yielded surface tensions of EVOH melts at different temperatures. To a good approximation linear variation of surface tension with respect to copolymer composition was observed. It indicates that conformational restrictions prevent surface excess of the low-energy units. Results on surface tensions are discussed in terms of different theoretical approaches. It turns out that the parachor approach is in excellent agreement with experimental data. The corresponding state approximation revealed decreasing surface energy with ascending ethylene content whereas the surface entropy remains approximately constant as long as vinyl alcohol units are in excess. [Copyright &y& Elsevier]

Abstract: A simple but efficient method has been followed for the synthesis of water soluble siloxane amphiphile by grafting poly(ethylene glycol) (PEG) onto the hydrophobic poly(hydromethyl siloxane) backbone. Systematic variations in the amount of PEG incorporations were carried out to get water soluble oligomers. The structural analysis of the systems was done by 1H NMR and GPC analysis. The solution behavior of these amphiphiles was studied. The presence of nonpolar microdomains was observed at concentrations ≥0.01g/dL for all the systems. Interestingly, I 3/I 1 ratio of pyrene fluoroprobe solubilised in aqueous solution of amphiphile suggests greater nonpolarity of microdomains in the system containing a higher PEG graft. The oligomers were shown to be surface active wherein, critical aggregation concentration decreased systematically with the decrease in the hydrophilic PEG substitutions. However, the system with a higher PEG substitution shows the close packed aggregates in the solution as suggested from the viscosity and fluorescence measurements. The contribution of polar and dispersion component towards the total surface energy was studied by the contact angle measurement by the sessile drop method. [Copyright &y& Elsevier]

Abstract: The densities of liquid NiCrAlMo quaternary alloys with a fixed molar ratio of Ni:Cr:Al (approximately as 73:14:13) and molybdenum concentration from 0 to 10 mass% were measured by a modified sessile drop method (MSDM). It was found that the density of the liquid NiCrAlMo quaternary alloys decreases with increasing temperature, but increases with the increase of molybdenum concentration. The molar volume of liquid NiCrAlMo quaternary alloys increases with the increase of temperature and molybdenum concentration. The density of liquid NiCrAlMo quaternary alloys calculated from the partial molar volumes of nickel, chromium, aluminum and molybdenum in the corresponding Ni-based binary alloys are in good agreement with the experimental results, means, within the error tolerance range the density of liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. [Copyright &y& Elsevier]

Abstract: The surface tension of molten Ni–W and Ni–Cr alloys was measured at 1773–1873K with an improved sessile drop method. And the recommended surface tension–temperature relationship was derived using linear regression method. It has been found that the surface tension of molten Ni–W and Ni–Cr alloys decreases with increasing temperature. The surface tension in present work is much higher than previous data with the difference of more than 170–220mNm−1. The large surface tension value and its low temperature coefficient obtained in the present study could be due to the high-purity of sample and the low partial oxygen pressure in the experimental atmosphere. [Copyright &y& Elsevier]

Abstract: In this work, the density of liquid Ni–Co binary alloys was measured with a modified sessile method (MSDM). It was found that the density of the liquid Ni–Co alloys decreases with increasing temperature and cobalt concentration in the alloys, and the molar volume of liquid Ni–Co binary alloys increases with the increase of temperature and cobalt concentration. The partial molar volume of cobalt in liquid Ni–Co binary alloy has been calculated approximately as [(6.78−4.82×10−4 T)−(1.74−1.67×10−3 T)× X Co]×10−6 m3 mol−1. Compared with the ideal mixing, the molar volume of Ni–Co liquid binary alloys shows a negative deviation. [Copyright &y& Elsevier]

Abstract: The wetting of MgO by molten magnesium was measured between 973 and 1273K using an improved sessile drop method. In this method, molten magnesium was set around the sample droplet to prevent oxidation of the magnesium droplet. A significant volume loss of the droplet was observed over 1073K due to the high vapor pressure, and the contact angle was underwent an unusual change over 1173K. The contact angle first decreased and then increased. This phenomenon occurred due to the pinning of the three-phase line at deep ditch. This change in the contact angle is an apparent change in contact angle. The intrinsic contact angle should be decided using the initial value or the maximum value just before the disappearance of the droplet. For any high vapor pressure system, such a change in contact angle can be observed at high temperatures. [Copyright &y& Elsevier]

Cell attachment and spreading to titanium-based alloy surfaces is a major parameter in implant technology. In this paper, substratum surface hydrophobicity, surface free energy, interfacial free energy and surface roughness were investigated to ascertain which of these parameters is predominant in human fibroblast spreading. Two methods for contact angle measurement were compared: the sessile drop method and the captive bubble two-probe method. The relationship between surface roughness and the sessile drop contact angles of various engineered titanium surfaces such as commercial pure titanium (cp-Ti), titanium–aluminium–vanadium alloy (Ti–6Al–4V), and titanium–nickel (NiTi), was shown. Surface free energy (SFE) calculations were performed from contact angles obtained on smooth samples based on the same alloys in order to eliminate the roughness effect. SFE of the surfaces have been calculated using the Owens–Wendt (OW) and Van Oss (VO) approaches with the sessile drop method. The OW calculations are used to obtain the dispersive (γd) and polar (γp) component of SFE, and the VO approach allows to reach the apolar (γLW) and the polar acid–base component (γab) of the surface. From captive bubble contact angle experiments (air or octane bubble under water), the interfacial free energy of the different surfaces in water was obtained. A relationship between cell spreading and the polar component of SFE was found. Interfacial free energy values were low for all the investigated surfaces indicating good biocompatibility for such alloys. [Copyright &y& Elsevier]

• A method is proposed to characterise collector strength in terms of attachment kinetics. • The attachment rate of particles to a capillary pinned bubble is measured. • An image processing technique is developed to quantify particle surface coverage. • Collectors can result in similar contact angle while showing distinct attachment kinetics. • The proposed method provides valuable additional information on collector performance. Particle attachment and detachment in froth flotation are complex processes and their measurement presents many challenges. Of particular interest is the effect of collectors at the bubble-particle scale, in order to assess the strength or collecting ability of these reagents. However, studies of the effect of collectors on particle attachment at the bubble-particle scale are scarce. In this work, we propose a methodology to characterise collector strength by measuring the attachment rate of particles to a capillary-pinned bubble. An image processing technique was developed to quantify bubble surface coverage over time, which was then used to determine particle attachment kinetics. The image analysis strategy is based on the sessile drop method and uses curve fitting to determine accurately the particle coverage. The methodology was used to assess the collecting ability of three chalcopyrite collectors. Interestingly, although very similar contact angle measurements were found for two of the collectors, they showed distinctly different particle attachment kinetics. It is proposed that this particle-bubble attachment method can be used to gain additional information not currently available from either contact angle measurements or bulk collector performance tests. [ABSTRACT FROM AUTHOR]