PSI - Issue 50

S.A. Filin et al. / Procedia Structural Integrity 50 (2023) 91–99 S. A. Filin at al. / Structural Integrity Procedia 00 (2022) 000 – 000

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relevant for parts made of non-ferrous metals - copper, aluminum and their alloys (Qin et al. (2006); Martin et al. (1999); Quaas et al. (2005 ); Muñoz et al. (2017); Aslan et al. (2021)). Common mechanical wiping of metals with traditional solvents leads to the appearance of scratches on the surface. A properly organized cleaning process can significantly increase the service life of metal optics, since re-treatment of the surface is an expensive process. Scratches that occur when wiping mirrors using traditional solvents, and fibers from wiping material, not only increase the scattering coefficient, but also reduce the optical damage and adhesive strength of optical coatings on mirrors, and, consequently, the resource of these expensive products (Kaplunov et al. (2015); Drobot et al. (1995)). This necessitated the creation of a non-contact technology for cleaning of metal optics (Kaplunov et al. (2015); Drobot et al. (1995); Drobot et al. (1996)).When solving the problem; the instability of a number of properties of halogenated hydrocarbons used for purification appeared (Akasaka et al. (2015)). Even fluor hydrocarbons, which are much more stable than chlorine-substituted ones, are inert to metals only in a chemically pure and dehydrated form even at room temperature. When they are contaminated in the presence of O 2 , H 2 O, hydroxyl groups of alcohols and some other organic substances, as well as under the influence of elevated temperature and light, freons can decompose with the formation of acidic and toxic products (HCl, HF, HBr, F 2 , Cl 2 , Br 2 , COCl 2 , COF 2 , fatty acids). Chemically acting on metal optics, they negatively affect it. Multiple use of chemically pure and dehydrated halogenated hydrocarbons without prior purification or stabilization of physicochemical properties also leads to the accelerating decomposition process with the formation of acidic and toxic products. The result - is metal corrosion and the impossibility of long-term use of expensive hydrocarbons. Stabilization of halogenated hydrocarbons and washing mixtures based on them occurs by adding small amounts of an inhibitor (Rysaev et al. (2007)), which slows down the destruction. Organic inhibitors are used, when heated solvents come into contact with metals such as aluminum and they are generally classified into antioxidants, acid acceptors, and metal stabilizers. Phenolic and amine type antioxidants are used to reduce the solvents degradation (Polevoy (2014)). A chlorinated solvent usually contains 0.05 – 0.2% of an antioxidant and 0.2 – 0.7% of an acid acceptor (Polevoy (2014); Bakirova et al. (2009)). To stabilize freons, a washing mixture containing phenols, organic nitro compounds, phenylhydrazine and hydrazobenzene, etc. is used (Polevoy (2014); Chemist's Handbook 21: Chemistry and chemical technology). Most halogenated hydrocarbons, used for stabilization, contain additives such as epoxy compounds, ammonium benzoate, etc. Acid acceptors of the epoxy type neutralize HCl formed in solvents, they can lead to contamination and corrosion of the metal (Potelov et al. (2006); Vukolov et al. (2006); Mitin et al. (2015); Minakova et al. (2008)). Works (Tsvetkov (2008); Antipov (2010); Antipov (2011)) reports an increase in the stability of hydrocarbons during metal cleaning at not high temperatures without using of contaminating stabilizers based on the use of fluorine-mixed hydrocarbons in the form of azeotrope with other solvents. The reason is that azeotropes are characterized by immutability of composition and boiling point. This reduces the cost and facilitates metal cleaning and solvent regeneration (Filin et al. (2019). In this case, the boiling point of the azeotrope is less than the boiling point of any of the solvents forming it, and the dissolving power can be higher than each of them. The low boiling point ensures more intensive evaporation from the cleaned surface and, as a result, more intensive cooling. This reduces the rate of destruction of the azeotrope itself and the metal to be purified. An effective method for stabilizing halogenated hydrocarbons with repeated use to obtain chemically pure and dehydrated hydrocarbons is distillation purification. The method also makes it possible to simultaneously obtain azeotropes of halogenated hydrocarbons with other solvents, since mechanical mixing of different solvents in the required proportion does not guarantee their azeotrope. 2. Materials and methods The studies were carried out on the example of exploitation of mirrors made of copper and its alloys in high power CO 2 lasers (Kaplunov et al. (2015)) Solvents of the "ultra high purity" brand were used, or the components of azeotrope were previously subjected to rectification purification and sublimation. We modeled mixtures that are closest to real contaminants formed on mirrors during abrasive processing. This is a mixture of pekkanifol resin, oils (diffusion oil "VO-5" brand, spindle oil and fatty contaminations from the hands,