Kinetics of formation and dissolution

The kinetics of formation and dissolution of such new phases, passive... 

Kovacevic D, van der Burgh S, de Keizer A, Stuart MAC (2002) Kinetics of formation and dissolution of weak polyelectrolyte multilayers role of salt and free polyirms. Langmuir... 

Development of superior CBPC products for the wide-ranging applications shown in Fig. 2.1 requires a fundamental understanding of their kinetics of formation and their properties. This topic is extensively addressed in Chapters 4-6. The dissolution model described in these chapters also helps in understanding the role of individual components in formation of ceramics and the end performance of the ceramics. In addition, the dissolution model explains how hazardous and radioactive components are stabilized in a phosphate matrix. The stabilization mechanisms are discussed in Chapters 16 and 17. 

A numerical solution, based on the model presented for a formation-dissolution mechanism, was derived by Miller (1981). The following two Figs 4.13 and 4.14 demonstrate the effect of micelles on adsorption kinetics. The effect of the rate of formation and dissolution of micelles, represented by the dimensionless coefficient nkfC Tj /D, becomes remarkable for a value larger than 0.1. Under the given conditions (D /D, =1, c /c , =10, n=20) the fast micelle kinetics accelerates the adsorption kinetics by one order of magnitude. 

Prinsen et al. [23] and Warren et al. [31] used dissipative particle dynamics to simulate dissolution of a pure surfactant in a solvent. Tuning surfactant-surfactant, surfactant-solvent, and solvent-solvent interactions to yield an equilibrium phase diagram similar to Fig. 1 at low temperatures except for the absence of the V i phase, they found that the kinetics of formation of the liquid crystalline phases at the interfaces was rapid and that the rate of dissolution was controlled by diffusion, in agreement with the above experimental results. 

On most corroding metals, the above reactions occur at an oxidized surface and, depending on the peroperties of the surface layer, passivation may occur by which the kinetics of metal dissolution are substantially supressed either by ohmic, ionic, or electronic transport at a surface passivating film or by electrocatalytic hindrance. In passivation phenomena, a steady state with a balance between the formation and dissolution of the surface film takes place. As a result, the ionic flux of metal ions dissolving through the passivating film is highly reduced. 

A number of macroscopic observations have been carried out on crystal formation and dissolution in various solvents by the use of optical and electron microscopes. The kinetic and dynamic properties of crystal growth, and dissolution have been investigated in various chemical contexts. The structural analysis of crystals is an indispensable method in chemistry. However, it is still difficult or even impossible to answer the question how a crystal is born. 

Cyclic voltammetric and potentiodynamic measurements in the system Ag(hkl)/Bi, H, CIO4 (+ Cl ) show that the kinetics of 2D Meads phase formation and dissolution depend on the structure of the substrate surface [3.119]. It was suggested that Meads surface diffusion may play an important role in the desorption kinetics. 

Formation and dissolution of 2D Me-S surface alloys and/or of 3D Me-S bulk alloys are strongly irreversible processes. The kinetics of these processes are considered in the following. 

D Me-S surface alloy and/or 3D Me-S bulk alloy formation and dissolution (eq. (3.83)) is considered as either a heterogeneous chemical reaction (site exchange) or a mass transport process (solid state mutual diffusion of Me and S). In site exchange models, the usual rate equations for the kinetics of heterogeneous reactions of first order (with respect to the species Me in Meads and Me t-S>>) are applied. In solid state diffusion models, Pick s second law and defined boundary conditions must be solved using Laplace transformation. 

Kinetic Aspects The kinetics of 2D phase formation and dissolution of organic adlayers were mostly studied by i—t, q —t or C-t single or multiple potential step experiments, and analyzed on the basis of macroscopic models according to strategies described in Chapter 3.3.3. Only rather recently, modern in situ techniques such as STM [20, 201, 453, 478, 479, 484, 487, 488] and time-resolved infrared spectroscopy (SEIRAS) [475,476] were applied to study structural aspects of these phase transitions at a molecular or atomistic level. 

Sht3] Shtansky, D.V., Nakai, K., Ohmori, Y, Formation of Austenite and Dissolution of Carbides in Fe-8.2Cr-C Alloys , Z. Metallkd., 90(1), 25-37 (1999) (Morphology, Phase Relations, Thermodyn. Calculation, Experimental, Kinetics, 47)... 

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