Vague concept of “reversible cleavage” in the theory of the surface tension of solids

Numerous derivations of the well-known Shuttleworth equation have been based on the unclear concept of “reversible cleavage” leading to the decisive step in any derivation - equalization of the surface free energy and surface stress. This is the key concept in contemporary surface thermodynamics of solids. But “cleavage” is not a surface process and, in this field, it cannot be a reversible operation. Besides, the “reversible cleavage” has no formal definition in the domain of the surface tension of solids that is an abnormal for any exact science. Consequently, this concept and all its corollaries including the Shuttleworth and generalized Lippmann equations have to be recognized as incorrect.     

Structure-mechanical approach to surface tension of solids

Some problems of applying the Lippmann equation to adsorption studies on solid electrodes are shortly reviewed. A novel nonthermodynamic approach to consider the role of elastic and plastic deformation of electrode surfaces during adsorption is proposed. The extremely thin electrode surface layers affected electrically and mechanically by adsorbate are supposed to be free of dislocations because of volume discrepancy. The nearest structure-mechanical analogs of such layers are the whisker crystals whose side surface could have one- and two-dimensional defects, but have no active dislocations. Like whiskers, surface metal layers should possess a high ultimate strength close to the theoretical one and a purely elastic deformation. Affected only by adsorbate, the surface electrode layer should be considered as absolutely elastic body, whose plastic deformation is impossible, i.e. the Lippmann equation and other equations containing terms of plastic deformation cannot be used in thermodynamics of the solid metal surface.     

Empirical equations of state for solids

A comparison of three one-parameter empirical equations of state due to Lennard-Jones, Bardeen, and Birch using Bridgman's experimental compression data shows that they do not generally fit the data within experimental error. Heuristic arguments are used to derive a well known three-parameter equation of state which includes these equations as special cases. Several simple two-parameter equations of state, including the Murnaghan equation, can be obtained as special cases of the general form. All of these two-parameter equations are shown to fit Bridgman's data within experimental error with about equal success. It is also shown that the general three-parameter equation, and hence its special cases, is consistent with the observation of Grover, Getting, and Kennedy that the log of the bulk modulus of solids is a linear function of compression. Several of the two-parameter special cases are shown to give satisfactory extrapolations.     

A note on surface stress and surface tension and their interrelation via Shuttleworth’s equation and the Lippmann equation

Some aspects of the thermodynamics of solid surfaces, in particular with respect to the surface stress, f, and surface tension, γ, including the case of solid electrodes, are examined in view of their controversial discussion in part of the recent literature. By inspection of the phenomenology that requires a distinction between f and γ, and of a toy model designed to highlight the underlying fundamental science, it is shown that some of the recent publications give misleading conclusions. These include [V.A. Marichev, Surf. Sci. 600 (19) (2006) 4527; E.M. Gutman, J. Phys. Condens. Matter. 7 (48) (1995) L663; D.J. Bottomley, T. Ogino, Phys. Rev. B 63 (2001) 165412]. In spite of claims to the contrary, the validity of the equations of Shuttleworth, Lippmann, and Couchman and Davidson is not impaired by the arguments of the aforementioned articles.     

Expressions of the radius and the surface tension of surface of tension in terms of the pressure distribution for nanoscale liquid threads

The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics （MD） simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.     

拉脱法测量纯水表面张力系数实验的研究

从实验和理论上对拉脱法测量表面张力系数的实验进行了研究.用微力传感器代替约利弹簧,并在此基础上改进了实验仪器.研究分析了使用约利弹簧和传感器测量表面张力系数实验的实验原理,指出了它们的区别,并给出了利用传感器测量表面张力系数实验的理论计算公式.改进后的实验降低了拉脱法测量表面张力系数实验的技术难度,提高了测量表面张力系数的精确度.     

极大值法测量表面张力系数

测量金属薄片从液体中拉出过程中液膜高度和拉力的关系,分析其产生的原因,给出液体表面张力系数的准确测量方案.     

Assessing the equation of state and comparing it with other relationships used for determining the surface tension of solids

Some facts regarding the equation of state (EQS) in calculating the surface tension of solids by means of contact angle measurements were manifested. In the present investigation, it was mathematically proved that the surface tension of a solid as estimated by the EQS is in fact equivalent to the Zisman critical surface tension for that same solid. Additionally, the applicability of the EQS's approach in attaining the surface tension of powdered solids by the aid of the capillary rise procedure is also discussed and its limitations are clarified. Furthermore, a methodology was devised so that the surface tension of solids as determined by the EQS could be compared with those calculated by approaches using components of surface tension. This methodology revealed that the applications of approaches based on the geometric mean (i.e. Owens/Wendt and van Oss et al. relationships) are restricted to achieving only high surface tensions of solids.     

相对法测量表面张力系数

从细管缓慢流出的液体,并不是呈现连续的液流,而是一些继续的液滴。通过对不同液体液滴大小的比较,可测得表面张力系数。     

液体表面张力系数实验装置的改进

对现有吊环法液体表面张力系数测量仪的水平调节装置、吊环升降装置存在的不足进行了改进,在原有仪器上增加了液体加热装置,以便对不同温度下的液体表面张力系数进行测量,实验说明新的实验装置更加科学合理.通过实验对比得出:新的实验装置操作方便、实验误差小、重复性好,有推广价值.     

Effect of surface tension on the mode selection of vertically excited surface waves in a circular cylindrical vessel

Singular perturbation theory of two-time-scale expansions was developed in inviscid fluids to investigate patternforming, structure of the single surface standing wave, and its evolution with time in a circular cylindrical vessel subject to a vertical oscillation. A nonlinear slowly varying complex amplitude equation, which involves a cubic nonlinear term,an external excitation and the influence of surface tension, was derived from the potential flow equation. Surface tensionwas introduced by the boundary condition of the free surface in an ideal and incompressible fluid. The results show that when forced frequency is low, the effect of surface tension on the mode selection of surface waves is not important.However, when the forced frequency is high, the surface tension cannot be neglected. This manifests that the function of surface tension is to cause the free surface to return to its equilibrium configuration. In addition, the effect of surface tension seems to make the theoretical results much closer to experimental results.     

液膜气泡法测洗涤溶液的表面张力系数

利用自制装置采用液膜气泡法测定了洗涤溶液的表面张力系数．由医用注射器充气形成球形液泡，通过与之连通的微压计测出液泡内外的压强差，运用杨氏-普拉斯方程计算出洗涤溶液的表面张力系数.     

拉脱法测液体表面张力系数的改进

对拉脱法测定液体表面张力系数的实验作了改进．减小Ⅱ形框横丝长度L,减短Ⅱ形框侧丝长度b,对由此引出的自升现象、α的计算公式等问题进行了相应的分析和处理,使实验用液量由原来的100mL减为5mL,并且提高了测量准确度。     

A kinetic approach to the calculation of surface tension of a spherical drop

In literature, surface tension has been investigated mainly from a Thermodynamics standpoint, more rarely with kinetic methods. In the present work, surface tension of drops is studied in the framework of kinetic theory, starting from the Sutherland approximation to Van Der Waals interaction between molecules. Surface tension is calculated as a function of drop radius: it is found that it approaches swiftly an asymptotic value, for radii of several times the distance of minimum approach D of the Sutherland potential. This theoretical asymptotic value is compared to experimental values of surface tension in plane surfaces of a few liquids, and is found in reasonable agreement.     

用电子秤测液体的表面张力系数

介绍了用电子秤测液体表面张力系数的原理和方法。     

毛细管探针法测定液体表面张力系数的进一步研究

采用较大直径的毛细管对探针法测量液体表面张力系数做了进一步研究.文中引用了Prokhorov提出的改进的瑞利公式,介绍了表面张力系数α的各相关公式的适用范围.实验中利用毛细管探针法测量了几个不同温度下蒸馏水在一直径为5.744.nm的毛细管中的上升高度,用Prokhorov公式计算α.实验测得的蒸馏水的表面张力系数与公认值的百分误差约小于0.13%.最后对实验结果的误差原因进行了分析.     

用分析天平测液体的表面张力系数

根据杠杆平衡原理，利用分析天平测液体的表面张力系数。