PSI - Issue 40

S.A. Filin et al. / Procedia Structural Integrity 40 (2022) 153–161 S. A. Filin at al. / Structural Integrity Procedia 00 (2022) 000 – 000

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From equation (1) it follows that the closer the values of the solubility parameters of the solvent and the solute, the better mixing of components occurs. Of course, the compatibility of the components to be mixed in a certain way depends on the proximity of their solubility parameters. However, Ilyin et al. (1997) it is shown that, since the "specific energy density of cohesion in composition consists of three different types of interaction, and then there are cases of mutual insolubility of the two components at the same values of the "specific density of cohesion energy" and, accordingly, the solubility parameters. This takes place when a certain type of interaction of one of the components differs greatly from the interaction of the same type of another component with the equality of the "specific energy density of cohesion". An attempt to improve the prediction of solubility in such cases by dividing the interaction in the compound into three components, i.e., to find the indicators responsible for each type of interaction, slightly corrected the situation due to the small statistical base of such indicators. Because of the difficulties in determining these components, the number of solvents, for which they are known, is limited. Moreover, for some solvents, all three components are not defined. Their values differ significantly among different authors for the same substance, due to imperfections and differences in their measurement methods, while the one- dimensional solubility parameter (δ) is uniquely d etermined for a significant number of substances. In (Ilyin et al. (1997)), an attempt was made to correlate the solvent solubility parameter (δ) with other solubility parameters, mainly based on the classification of solvents by their polarity. Such correlation allows the selection of components, which are fully compatible upon dissolution. The correlation of the parameter (δ) is studied taking into account the polar selectivity of solvents based on their donor-acceptor properties. To elucidate the influence of the role of optical parameters (plasma formation threshold, adhesion of optical surface, geometric shape, reflection coefficient, etc.), the relationship of these characteristics with the energy characteristic of detergent medium in the process of physicochemical cleaning was investigated. In this case, the choice of detergent medium for cleaning of metal optics should be determined taking into account the behavior of their characteristics during their cleaning and operation. The dissolution process always involves several stages: 1) transfer of solvent to the cleaning surface, at which the reaction occurs; 2) dissolution; 3) removal of reaction products from the surface. The total dissolution rate is determined by the rates of the individual stages. In most cases, the dissolution processes, used in industry, take place in the diffusion region. The dissolution rate is determined by the diffusion rate of the active soluble component. General equations of the diffusion-kinetic regime were obtained under the assumption that the conditions of diffusion transport do not depend on the conditions of the dissolution reaction in the "outer" and "inner" diffusion regions (Frank-Kamenetsky (2008)). This assumption is valid if all areas of the surface can be considered equally accessible in terms of diffusion. Such a surface is called equally accessible. The reaction rate on the surface ( jK ) in this case is proportional to the concentration of the active dissolved component ( C ) near the surface to some extent (α), wh ich determines the reaction order: jK KC   (2) The diffusion flux to the surface ( jD ) can be determined using the linear diffusion coefficient ( β ): 0 ( ) jD C C    , (3) where C 0 - is the concentration of the dissolved component in the volume. In a stationary state, the amount of substance that reacts on the surface is equal to the diffusion flux: 0 ( ) KC C C     , (4) Equation (4) is the general equation of the diffusion-kinetic regime. For a first-order reaction, solving the equation with respect to C gives the expression: