The Water Wettability of Metal Surfaces

Abstract

Low contact angles with water may be obtained on the surfaces of chemically reactive metals by a process involving chemical cleaning with powerful oxidizing acids, followed by electropolishing to restore smoothness to the etched specimens. By using highly refined handling techniques, contact angles in the range, 0-11°, were obtained on aluminum, brass, copper, magnesium, nickel, stainless steel and zinc. The low contact angles are considered a good indication that organic contamination was virtually absent from the electropolished surfaces. The possibility of spurious inorganic contamination, apart from the normal oxide film, also was considered, and, in the case of copper electropolished in phosphoric acid, the residual phosphate on the surface was estimated by coulometric reduction and shown to be much less than a monolayer. The preparatory technique used in this study is applicable to a wide variety of metals and alloys and serves to demonstrate experimentally the inherent water wettability of clean metal surfaces. It also provides a means of preparing clean, smooth substrates on ^which fatty acids or other compounds may be deposited and their behavior observed in determining wettability and adhesion. Mechanical polishing, followed by exhaustive rinsing with hot or cold redistilled organic solvents, was not effective in producing low contact angles on metal surfaces.

Wettability of copper and polytetrafluoroethylene surfaces with water—the influence of environmental conditions

“…These values and the values obtained from our experiments are in close agreement; in the group comprising Erb [29], White [26, 271, Plabin and Bessonov [25], Bartell and Smith [23], and Boyes and Ponter [30], angles of approximately 10 deg are found a t low pressures which increase rapidly to 60-70 deg a t atmospheric pressure. The results presented by Trevoy and Johnson [24] appear to be in disagreement since they measured contact angles 0 -11 deg at atmospheric pressure and in equilibrium with water vapour. However in their experimental proceedure no attempt was made to remove the oxide layer which would be present on a metal surface in an air environment and hence the results do not represent an oxide free metal surface.…”

Fabrication and Applications of 3D Nanoarchitectures for Advanced Electrocatalysts and Sensors

“…[209,213] The metal and metal oxides, which are the main components of the electrocatalysts for ORR and OER, originally have a hydrophilic surface. [214,215] The innate hydrophilicity can be further strengthened by the nanostructuring of electrocatalysts such as NSTF. According to the Wenzel equation, the intrinsic hydro-or aerophilicity of the materials can be prominently augmented by roughening the surface of the materials with nanostructures, which results in an increased propensity to flood on the nanostructures.…”

Liquid Marble Interaction Gate for Collision-Based Computing

“…Experiments also indicated that pure UHDPE LMs evaporate at a comparable rate to pure nickel LMs. This is due to a balancing act between the short narrow pores of the nickel LM, the long wide channels of the UHDPE LM, and the much larger contact angle of UHDPE compared to nickel [40,41]. The larger grain size of the UHDPE creates longer channels for water vapour to traverse.…”