Wettability definition

Thermal Inactivation. Heating the wood surface to temperatures above 150 to 200°C definitely has been shown to cause poor adhesion with phenolic adhesives and, possibly, urea adhesives. Early research (60) verified that overheated wood was less wettable and tended to absorb less water from the adhesive. Whether this is caused by extractives, pyrolysis, oxidation of hydroxyl groups, or other chemical reactions at the wood surface has been the subject of much debate. Further, the mechanisms of thermal or "surface" inactivation may vary from species to species. 

This special class of brazes reacts chemically with the surfaces of ceramic components to produce wettable products with metallic characteristics, such as TiO, TiC x or TiN x as described in Sections 6.3 and 7.2. Thus the wetting is due to an in situ metallization . By definition, the brazes must contain chemically reactive elements such as Ti that are often added to eutectic brazes similar to those developed for joining metal components. Many sessile drop experiments have shown that active metal brazes can wet a wide range of ceramics when a suitable inert environment is used. Particularly high standards of environmental inertness... 

Wettability of a solid surface definition and assessment The concept of wettability of a solid by a liquid is directly related to the wetting processes. This concept is specially useful in the fields of detergency, lubrication or enhanced oil recovery. In the context of the oil industry, proposals were made by Briant and Cuiec (1972) for the experimental assessment of wettability, which was defined in terms of the thermodynamic affinity of a solid surface for a liquid. 

The ACCA and APCA on an ideal solid surface are identical by definition, and are referred to as the "ideal contact angle (ICA)". As will be explained below, it is the value of the ICA that is required for the characterization of the wettability of a solid substrate in terms of its surface tension. Also, all predictions of wetting behavior start with the ICAas their basis. Therefore, even though ideal surfaces are rarely encountered in practice, the concept is of fundamental importance. 

Before starting, it is important to set some definitions. We assume that in a gravitational field when a liquid contacts a solid, some interfacial area is formed i.e., the liquid wets the solid. In the next section, we present a definition of wettability — the contact angle. In contrast, the term spreading refers to the motion of a liquid film over a solid either by spontaneous spreading or by forced spreading. 

Particle Adhesion in Relation to Wettability of Solid Surfaces. Adhesion is governed by certain properties of the contiguous bodies that also determine the susceptibility of these bodies to wetting by liquids [8, p. 43]. Hence, there is a definite relationship between the contact angle (wetting angle) of the contiguous bodies and particle adhesion [21 ]. 

The wetting angle can be used to estimate the adhesive tendencies of powders [196]. For the adhesion of the particle layer, a definite correlation has been found between wettability and adhesive force. 

Measurement of dye adsorption with the purpose of determining wettability of sandstone cores was first proposed by Holbrook and Bernard (3). These authors defined relative water wettability as the fraction of the total surface area of a core that is contacted by injected water. There follows from this definition that if this fractional area were found to be a function of the saturation of the core then relative water wettability is also saturation dependent. 

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