A Comparison of Surface Tension,Viscosity, and Density of Sn and Sn–Ag Alloys Using Different Measurement Techniques

This work is aimed at comparing several methods for the measurement of physical properties for molten Sn and Sn–Ag alloys, namely, surface tension, density, and viscosity. The method used for viscosity in this work is the modified capillary method. For surface tension and density, the data used for comparison were previously measured using the maximum bubble pressure method and the dilatometer technique, respectively, for four Sn–Ag alloys having (3.8, 32, 55, and 68) at% Ag. The results are compared with those obtained using a new method based on a fluid draining from a crucible under the influence of gravity, designated the Roach–Henein (RH) method. This new method enables the determination of these three physical properties in one set of measurements. Liquid Sn was used as well as two liquid Sn–Ag alloys having (3.8 and 34.6) at% Ag with the RH method. It was determined that the RH method may be used to simultaneously obtain surface tension, viscosity, and density and that the errors associated with these measurements were similar to those obtained using traditional and separate techniques. Comparisons of the measured viscosity and surface tension to those predicted using thermodynamic models will also be presented. Finally a comparison of mixing model predictions with the experimentally measured alloy surface tension and viscosity is also presented.     

Density and surface tension polytherms of gallium-lead melts

The density and surface tension of gallium-lead melts have been determined using the sessile drop technique in the temperature range of 600–1000°C. According to the form of polytherms of surface tension of a system with Ga-Pb exfoliation, a conclusion was made about the primary distribution of lead ions on the melt-vapor boundary. The excess entropies of melt formation were calculated. The comparison of experimental and calculated values of excess entropies showed that primary interaction between similar ions highlights the linear character of density polytherms.     

Effects of elemental additions and superheat on melt surface tension and metallic glass embrittlement

Additions of antimony, selenium, tellurium and some other alloying elements to iron-nickel base alloys have been investigated with regard to effects on melt surface tension and resultant metallic glass formation and characteristics. Surface tension of the molten alloys has been measured as a function of composition and melt temperature using a variation of the maximum bubble pressure method. The density of molten Fe₄₀Ni₄₀B₂₀ alloy has been measured as a function of temperature. Attempts to chill block melt-spin and alloys of the present investigation into metallic glass ribbons were largely successful. A few compositions were partially crystalline in the as-cast state and even fewer were not castable at all. The amorphous structure of ribbons made was assessed by X-ray diffraction, differential scanning calorimetry, and embrittlement temperatures for one hour anneals. A correlation has been established between changes in melt surface tension and metallic glass embrittlement temperature with the addition of surface active elements.     

Surface tension and density measurement of liquid Si–Cu binary alloys

Surface segregation is very important for understanding the surface tension of binary systems. In case of a regular solution, the surface segregation is calculated using the Butler model. However, in the case of a complex system, like those forming intermetallic compounds, it is difficult to express the surface segregation. In order to discuss surface segregation in systems forming intermetallic compounds, we measured the density and surface tension of a Si–Cu binary system. We found the effect of clusters in both density and surface tension experimental data. The composition dependence of surface tension was expressed by a modified ideal solution model.     

Density and Surface Tension of Electromagnetically Levitated Cu–Co–Fe Alloys

The density and surface tension of Cu–Co–Fe alloys have been measured using the non-contact technique of electromagnetic levitation. At temperatures above and below the liquidus point, the density and surface tension are linear functions of temperature. The experimental density results can be predicted by means of the regular solution model from the binary phases alone, i.e., no assumption about ternary interactions needs to be made. The surface tension values are in good agreement with numerical solutions of the Butler equation if the known Gibbs excess energies are used. It is found that, for Cu–Co–Fe, it is possible to predict the surface tension from the binary systems as well. In addition to this, the surface tension is insensitive to substitution of the two transition metals, Co and Fe.     

Prediction of the Surface Tension of Refrigerants and Their Binary Mixtures

The use of scaling principles for the prediction of surface tension was studied. The temperature dependences of the capillary constant, density difference on the saturation line, and surface tension were investigated. New relations containing only a few constants were proposed, which made it possible to calculate the capillary constant and surface tension. On the basis of theoretical and experimental studies, equations have been determined for the calculation of the surface tension of poorly studied refrigerants over wide regions of the state parameters. Relations are also proposed that may be used for calculating the surface tension of binary mixtures at specified compositions of the liquid phase. An equation of the surface tension for reduced isotherms was proposed. Results of investigations of the surface tension of binary mixtures, R116/23, R22/14, R134a/152a, and R22/142b, are presented.     

Zum Einfluss von in Flüssigkeiten unter Druck gelösten Gasen auf Grenzflächenspannungen und Benetzungseigenschaften

Measurements of interfacial tensions of water and ethanol in dense carbon dioxide up to 10 MPa and 373 K were performed. Also, in order to predict the wettability of these liquids on teflon and glass surfaces in the presence of carbon dioxide, contact angles between these liquids and both surfaces were determined under the same conditions of pressure and temperature. The interfacial tension were measured according to the pendant drop method. A mathematical derivation for the evaluation of the interfacial tension according to the geometry of the pendant drop and the difference of the density between the phases is presented. The contact angle determinations were performed using both the static and the dynamic method. The results show that because of the solubility of carbon dioxide in the liquids, the measured interfacial tensions are much lower than the interfacial tension of the pure substances. The interfacial tension appears as a function of only the density of CO₂ above its critical temperature [1]. Even though the solubility of carbon dioxide in the liquid phase affects the interfacial tension, such a clear relation between these variables, like the one between the interfacial tension and the density of carbon dioxide, cannot be observed. The excess concentration on the interphase, as a measurement of adsorption according to Gibbs, was calculated for both systems. The contact angle of water on teflon surface increases with pressure until total non wetting is reached. On the other hand, the contact angle of ethanol decreases with the increasing pressure until spreading occurs. The same phenomena was noted for the wetting characteristic of water on glass surface. The contact angle of water increases as pressure increases. Ethanol spreads totally on the surface of glass at all evaluated pressures. With the dynamic method, contact anglesgreater than the ones obtained with the static method were measured.     

The Surface Tension of Undercooled Binary Iron and Nickel Alloys and the Effect of Oxygen on the Surface Tension of Fe and Ni

The surface tension of the undercooled binary alloys, iron–nickel and nickel–cobalt, was measured as a function of composition and temperature using the oscillating droplet method combined with electromagnetic levitation. The measurements cover a wide temperature range, including the overheated as well as the undercooled regime. In addition, the effect of oxygen on the surface tension of the elements, iron and nickel, has been determined. When exposed to an oxygen/helium gas flow of constant composition and flux, the surface tension decreases exponentially with increasing exposure time. The oxygen content in the gas mixture was monitored by a gas analyzer using a zirconia transducer. In addition, the amount of oxygen in the sample was determined by X-ray photo-electron-spectroscopy (XPS) before the experiment as well as for processed samples.     

Thermophysical Properties of Ag and Ag–Cu Liquid Alloys at 1098K to 1573K

The surface tension and density of liquid Ag and Ag–Cu alloys were measured with the sessile drop method. The sessile drop tests were carried out at temperatures from 1098K to 1573 K, on cooling (temperature decreasing stepwise) under a protective atmosphere of high purity Ar (6N). The density of liquid Ag and Ag–Cu alloys decreases linearly with increasing temperature, and an increase in concentration of copper results in a lower density. The surface tension dependence on temperature can be described by linear equations, and the surface tension increases with increasing Cu content. The results of the measurements show good agreement with existing literature data and with thermodynamic calculations made using the Butler equation.     

Surface free energy of polymers

A critical analysis of various methods of determining the surface free energy of solids, especially polymers, was carried out. It was shown that for the purpose of estimating the surface free energy (SFE) of polymers, their critical surface tension, whose numerical value is close to that of the SFE, can be determined by the Zisman method. Data on the critical surface tension of several hard polymers were obtained. The critical surface tension of certain highly elastic materials (cross-linked rubber NK, SKI-3, SKB, SKN-18, SKN-26, and SKN-40) was measured. The results were comparable to values of the cohesion energy density for these materials.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 5, No. 6, pp. 670–676, November–December, 1969.     

Measurement of surface tension and specific heat of Ni-18.8 at.% Si alloy melt by containerless processing

The surface tension and specific heat of superheated and undercooled Ni-18.8 at.% Si alloy melt have been measured by the oscillating drop method and the drop calorimetry technique in combination with electromagnetic levitation, respectively. The surface tension follows a linear relationship with temperature within the range of 1370–2100 K. The surface tension at the melting temperature and the temperature coefficient are determined to be 1.796 N/m and −3.858 × 10⁻⁴ N/m/K, respectively. The specific heat is determined to be 40.80 ± 1.435 J/mol/K over the temperature range 1296–2000 K. The maximum undercooling of 178 K is achieved in the experiments. Based on the measured data of surface tension and specific heat, the viscosity, solute diffusion coefficient, density and thermal diffusivity of liquid Ni-18.8 at.% Si alloy are calculated.     

Surface tension of liquid Al–Cu–Ag ternary alloys

Surface tension data of liquid Al–Cu–Ag ternary alloys have been measured contactlessly using the technique of electromagnetic levitation. A digital CMOS-camera (400 fps) recorded image sequences of the oscillating liquid sample and the surface tension was determined from an analysis of the frequency spectra. Data were obtained at temperatures above the melting point. Samples covered a broad range of compositions. In all cases, the surface tensions could be described as linear functions of temperature with a negative slope. The data were compared to thermodynamic model calculations using the ideal- and subregular solution approximation. It was found that, apart from samples where the composition is close to one of the binary margin phases, the surface tensions of the ternary alloys can be described by the ideal solution model.     

基于压浮原理的单晶硅球密度比较测量方法研究

为了克服单晶硅球密度测量静力称重法精度受液体表面张力的影响,研究了压浮法进行单晶硅球密度精密比较测量方法和测量系统。在一定的温度下,调节压力,利用液体压缩系数控制液体密度使标准单晶硅球和被测单晶硅球稳定悬浮于工作液体中,通过温度、压力和悬浮高度的测量,计算出二者之间的密度差值。通过双层控温系统保证了液体温度长期波动在±0.25 mK内,利用标准单晶硅球在不同温度-压力悬浮条件线性关系计算出液体压缩系数。试验证明,压浮法测量装置实现了单晶硅球密度差值的精密测量,标准测量相对不确定度为2×10^-7。     

Experimental study of density,surface tension,and contact angle of Sn–Sb-based alloys for high temperature soldering

The density and the surface tension of binary Sn–Sb and ternary Sn–Sb–Cu liquid alloys have been measured over a wide temperature range by the sessile-drop method. The experimental data for the surface tension were analyzed by the Butler thermodynamic model. Investigations of the wetting behavior of these alloys on the Cu and Ni substrates in a vacuum were also performed.     

Surface tension of mercury on glass,molybdenum and tungsten substrates

The surface tension of mercury on a glass substrate has been determined by the sessile drop technique. It was found that the uncorrected value of surface tension varied with changes in the drop diameter in the range from 0.60 to 4.10 cm. From the Worthington equation for curvature a corrected surface tension of 456 dyn/cm was obtained for the 4.1 cm diameter drop, a value which is in reasonable agreement with previous investigations. However, application of a curve fitting procedure to the results from the smaller drops gave a corrected surface tension which was approximately independent of diameter but at a smaller average value of 413 dyn/cm. The surface tension of a 1.20 cm diameter drop was also measured on tungsten and molybdenum substrates and, in general, corrected values larger than on glass were derived. It is suggested that the small corrected values obtained for drops ⩽2.06 cm in diameter are due to adsorption of impurity from the glass substrate.     

Surface tension of liquid Cu and anisotropy of its wetting of sapphire

Precise surface tension data of liquid Cu are fundamental for studying its interaction with differently oriented single crystalline sapphire surfaces. For this reason, the surface tension of liquid Cu was measured covering a wide temperature interval of 1058 °C ≤ T ≤ 1413 °C. To avoid contamination of the sample from contact with container walls, the measurement was performed contactlessly in an electromagnetic levitation furnace using the oscillating drop method. A fast digital CMOS-camera (400 fps) recorded top view images of the oscillating sample. From an analysis of the frequency spectrum the surface tension was determined. The measured surface tension of Cu was used to calculate interfacial energies from contact angles of liquid Cu droplets, deposited on the C(0001), A(11-20), R(1-102) and M(10-10) surfaces of sapphire substrates. These were measured by means of the sessile drop method at 1100 °C using a drop dispenser. Within the first minutes of contact with the sapphire substrates, the contact angles of liquid Cu droplets rise to their equilibrium values. From these, in addition to interfacial energies also works of adhesion were determined.     

Surface Tension and Viscosity of Succinonitrile– Acetone Alloys Using Surface Light Scattering Spectrometer

Using a surface light scattering spectroscopic technique, the surface tension and viscosity of pure succinonitrile (SCN) and SCN–acetone alloys at 0.86, 1.69, and 2.25 mol% have been determined. The surface light scattering technique, and the procedures used for making the alloys and measuring their concentrations, are presented. Analysis indicates our interfacial surface tension and viscosity measurements have an uncertainty of ±2% and ±10%, respectively. The surface tension and viscosity were measured at various temperatures yielding relations among surface tension, viscosity, temperature, and concentration in SCN–acetone alloys.     

The stress intensity factor for a deep surface crack in a finite plate

A stress intensity factor solution has been determined for the case of a surface crack in a finite width plate. This solution is for tension or bending and includes a finite area correction factor. It has been shown that using this new stress intensity factor solution it is possible to correlate fatigue crack growth data measured on surface cracked plate specimens with conventional through crack data.     

Surface tension of γ-TiAl-based alloys

Within the Integrated Project IMPRESS, funded by the EU, a concerted action was taken to determine the thermophysical properties of a γ-TiAl-based alloys, suitable for casting of large turbine blades for aero-engines and stationary gas turbines. The challenge was to develop a castable alloy, free of grain refiners and susceptible to heat treatment. Owing to the high reactivity of this class of alloys, many difficulties were encountered to process the liquid phase in a crucible. This prevented also the measurements of specific heat, viscosity and electrical conductivity in the liquid phase. However, surface tension and density could be measured using container-less techniques. For the surface tension determination, both the oscillating droplet method by the electromagnetic levitation as well as a combined method using two methodologies in one test (i.e. the pendant drop and sessile drop) by an advanced experimental complex that has been designed for investigations of high temperature capillarity phenomena were applied. All the quantities have been obtained as a function of temperature, in some cases also in the undercooled liquid. In this article, we report a comparative discussion on the results obtained for the surface tension of Ti–Al–Nb and Ti–Al–Ta alloys, together with the corresponding theoretical values calculated by thermodynamic models.     

Oxygen partial pressure dependence of surface tension and its temperature coefficient for metallic melts: a discussion from the viewpoint of solubility and adsorption of oxygen

Surface tension of molten Si, Ag, and Fe–18Cr–8Ni alloy (Type-304 stainless steel) were measured as a function of the temperature and oxygen partial pressure of an ambient atmosphere by an oscillating drop method using electromagnetic levitation, which assures measurement over a wide range of temperatures below and above the melting point and of oxygen partial pressure. For molten silicon, the lower limit of measured temperature was determined by equilibrium oxygen partial pressure for SiO₂ formation; as oxygen partial pressure increases, undercooled conditions necessary for taking measurements become smaller. This is attributed to the low solubility of oxygen in molten silicon. For Ag, however, surface tension can be measured in a wide range of temperature and oxygen partial pressures due to the high solubility of oxygen. A boomerang-shaped behavior of surface tension was observed for Ag in an atmosphere with high oxygen partial pressure; surface tension has a maximum value when plotted against temperature. This boomerang-shaped behavior is attributed to desorption of oxygen at high temperature; surface tension increases with increasing temperature. The boomerang-shaped behavior was also observed for Fe–18Cr–8Ni alloy.