Topic
Sessile drop technique
About: Sessile drop technique is a(n) research topic. Over the lifetime, 2827 publication(s) have been published within this topic receiving 68943 citation(s).
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TL;DR: In this paper, a semi-theoretical approach was proposed to estimate the surface energy of solids in the absence of direct experimental measurement. But this method was not suitable for the case of high-index surfaces.
Abstract: An equation is derived on semi-theoretical grounds which expresses the solid-vapour surface free energy as a function of the liquid surface tension and the solid-liquid interfacial free energy. A means of calculating reliable values for the solid-liquid energy is presented, which then allows an accurate estimate of solid surface energy at the melting temperature, Tm, to be made for the large number of elements for which dependable liquid surface tension data exist. A method of estimating surface entropy is presented, and has been used to calculate the energies typical of “average”, high-index surfaces at temperatures ranging from 0 K to Tm. It is felt that this paper describes the most accurate method presently available for the calculation of the surface energy of solids in the absence of direct experimental measurement.
1,483 citations
TL;DR: The drop itself can generate one of the essential conditions for ring formation to occur: contact line pinning, and it is shown that when self-induced pinning is the only source of pinning an array of patterns-that include cellular and lamellar structures, sawtooth patterns, and Sierpinski gaskets-arises from the competition between dewetting and contact linePinning.
Abstract: Ring formation in an evaporating sessile drop is a hydrodynamic process in which solids dispersed in the drop are advected to the contact line. After all the liquid evaporates, a ring-shaped deposit is left on the substrate that contains almost all the solute. Here I show that the drop itself can generate one of the essential conditions for ring formation to occur: contact line pinning. Furthermore, I show that when self-induced pinning is the only source of pinning an array of patterns---that include cellular and lamellar structures, sawtooth patterns, and Sierpinski gaskets---arises from the competition between dewetting and contact line pinning.
1,135 citations
TL;DR: In this paper, the influence of Cu-coating on the spreading kinetics and equilibrium contact angles of aluminum on ceramics using a sessile drop technique was investigated.
Abstract: The purpose of this study was to investigate the influence of Cu-coating on the spreading kinetics and equilibrium contact angles of aluminum on ceramics using a sessile drop technique. Al2O3 and SiC plates were coated by electroless plating. The copper film overcomes the low wetting of the uncoated samples by dissolution in the drop at 800 °C in argon, showing an intrinsically favorable effect on the adhesion energy. Just after 2 min, the contact angle decreased to 12.6° and 26°for Al/Cu–Al2O3 and Al/Cu–SiC, respectively. However, a de-wetting behavior was observed, reaching equilibrium contact angles of 58.3° and 45.5° for the couples. The dissolution reaction rate at the triple junction was so high that the spreading process was controlled by local diffusion rather than chemical reaction kinetics.
963 citations
Book•
01 Jan 1999
TL;DR: Wetting properties of metal and non-metallic compounds have been studied in this paper, where surface and interfacial energies in solid / liquid / vapour systems have been analyzed.
Abstract: Chapter headings and selected sub-headings: Series Preface. Preface. Fundamental Equations of Wetting. Surface and interfacial energies in solid / liquid / vapour systems. Dynamics of Wetting by Metals and Glasses. Non-reactive wetting. Reactive wetting. Methods of Measuring Wettability Parameters. Sessile drop experiments. Surface Energies. Data for metals and alloys. Data for non-metallic compounds. Wetting Properties of Metal / Metal Systems. Effects of alloying elements. Systems that form intermetallic compounds. Wetting Properties of Metal / Oxide Systems. Non-reactive pure metal / ionocovalent oxide systems. Effect of electronic structure of the oxide. Wetting of fluorides. Wetting Properties of Metal / Non-Oxide Ceramic Systems. Metals on predominantly covalent ceramics. Wetting Properties of Metal / Carbon Systems. Non-reactive systems. Reactive systems. Wetting by Glasses and Salts. The glassy state. Wetting behaviour. Wetting When Joining. Flow into capillary gaps. Effects on mechanical properties. Appendices. List of symbols. Index
887 citations
TL;DR: It is argued using experimental data that contact lines and not contact areas are important in determining wettability and that Wenzel's and Cassie's equations are valid only to the extent that the structure of the contact area reflects the ground state energies of contact Lines and the transition states between them.
Abstract: We argue using experimental data that contact lines and not contact areas are important in determining wettability. Three types of two-component surfaces were prepared that contain "spots" in a surrounding field: a hydrophilic spot in a hydrophobic field, a rough spot in a smooth field, and a smooth spot in a rough field. Water contact angles were measured within the spots and with the spot confined to within the contact line of the sessile drop. Spot diameter and contact line diameter were varied. All of the data indicate that contact angle behavior (advancing, receding, and hysteresis) is determined by interactions of the liquid and the solid at the three-phase contact line alone and that the interfacial area within the contact perimeter is irrelevant. The point is made that Wenzel's and Cassie's equations are valid only to the extent that the structure of the contact area reflects the ground state energies of contact lines and the transition states between them.
658 citations