Interfacial Forces in Dispersion Science and Technology

Abstract

Interfacial forces determine many phenomena in dispersion science and technology. Eight types of interfacial forces are classified in this article. A general equation for all of them is derived here, with particular equation for each of them (being valid for simplified geometries, such as spheres, cylinders, etc.). As a new element, an interfacial anti-stretching force is introduced in this article, being equivalent to the definition of the interfacial energy in terms of tension as understood by Young. The differences and similarities between the interfacial gradient force and the interfacial spreading force (the Marangoni force) are shown. The well-known case of the liquid bridge induced interfacial force is supplemented by its less known version of a gaseous bridge induced interfacial force.

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

“…Gravity pulls the liquid copper sitting on top of the ceramic coating down into its cracks. On the other hand, penetration of liquid copper into the cracks of the ceramics is opposed by the interfacial capillary force [36][37][38][39]. In this sub-chapter, these two opposing forces are analyzed to show whether liquid copper will penetrate or not through the cracks in the ceramic.…”

A Kelvin-féle görbület kontra a Gibbs-féle felület: a nano-termodinamika két paradigmája

“…A Kelvin paradigma tarthatatlanságának a fenti kettõn túl még több oka van: 3). "elfeledkezik" a Gibbs féle felületi tagról, ami a fázis felületével arányos (lásd lent), ahonnan egyébként a Laplace-féle nyomás is levezethetõ [23][24] , így azt felesleges ide visszahelyettesíteni, 4). ellentmond a Gibbs-féle csíraképzõdési elméletnek 17 ahol G m,kap (J/mol) a hengeres kapillárisban lévõ folyadék moláris Gibbs energiája, r kap (m) a hengeres kapilláris sugara, (fok) pedig a folyadék peremszöge a kapilláris belsõ falán, gõzközegben.…”

A comparison between liquid drops and solid particles in partial wetting

“…At the point of contact the drop radius is R 0 and the free energy is E(=180°) =  SG A + 4R 0 2 , where A is the planar surface area and  SG is the solid-gas interfacial tension ( Figure 1). Note that  SG and can be defined as excess interfacial free energies per unit area [26]. For liquid and solid interfaces, the liquid-gas surface tension  and the solid-fluid interfacial tension  i are the derivatives of the free energy with respect to the area (at constant temperature T, total volume V and number of molecules n),  or i ( ) , , [27].…”