Macroscopic interface treatment

In developing criteria for the ranking of adhesive formulations or adherend surface treatments or primers, it is necessary to distinguish between two different situations. In one case (contact adhesion), a true interface is believed to exist across which intermolecular forces are engaged, while in the other, an interphase is formed by diffusive interpenetration or interdigitation between the adhesive and the adherend (diffusion interphase adhesion). Even in the case of contact adhesion, more often than not, an mi vphase of macroscopic thickness forms on... 

An emulsion occurring between oil and water phases in a process separation or treatment apparatus. Such emulsions can have a high solids content and are frequently very viscous. In this case the term interface is used in a macroscopic sense and refers to a bulk phase separating two other bulk phases of higher and lower density. Other terms cufflayer , pad layer , or rag layer emulsions . An older term for the continuous (external) phase in micellar dispersions. See also Continuous Phase, Micelle. See Dispersed Phase. 

In preparation for our subsequent treatment, we now consider a macroscopic two-phase fluid system with a planar interface of area s separating the bulk phases a and j. For the description of surface phenomena, the concentrations of the various components, p, and the components of the stress tensor d must be specified. In the interior of the bulk phases, the concentrations, be... 

In looking at the basic mechanisms of lubricated sliding friction, the major emphasis falls on the adhesive process because a p/ilonj. it is the one most likely to be influenced by the presence of the lubricant at the rubbing interface. The mechanisms to be considered here in particular are those that make their effect felt in thin film or boundary lubrication. The action of macroscopic liquid films, generated hydrodynamically or otherwise, are not included in this treatment because the surfaces are completely separated from each other the meaning of friction in such cases is discussed in Chapter 2. 

Wafer bonding is a process by which two mirror-polished wafers of any materials adhere to each other at room temperature without the application of any macroscopic gluing layer or external force. The bonding is achieved through van der Waals force. Wafer bonding achieved at room temperature is usually relatively weak compared to metallically, covalently, or ionically bonded solids. Therefore, for many applications, the room-temperature bonded wafers have to undergo a heat treatment to strengthen the bonds across the interface. 

Adhesion is an interfacial phenomenon that occurs at the interfaces of adherends and adhesives. This is the fact underlying the macroscopic process of joining parts using adhesives. An understanding of the forces that develop at the interfaces is helpful in the selection of the right adhesive, proper surface treatment of adherends, and effective and economical processes to form bonds. This chapter is devoted to the discussion of the thermodynamic principles and the work of adhesion that quantitatively characterize the surfaces of materials. Laboratory techniques for surface characterization have been described which allow an understanding of the chemical and physical properties of material surfaces. 

Most important is the role played by the fluctuation-dissipation theorem in theoretical treatments, as it may be regarded as an interface between the microscopic and the macroscopic properties of a sample. It provides us with a precise prescription of how to proceed when these two are to be related. On the microscopic side, theoretical analysis of dynamical models usually enables us to make a calculation of equilibrium correlation functions for all properties of interest. The fluctuation-dissipation theorem then relates these correlation functions with the results of measurement, as described by the various response functions. 

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