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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taken in equal proportions) and surfactants of the "Progress" brand in an amount of 200 mg. The amount of surfactant in all experiments was 2 weight %. Since the mass of peccanifol resin in contaminations can vary depending on the technological process and the achieved quality of processing, the following ratios of peccanifol resin and a mixture of oils were used - 75 : 23; 60:38; 45:53; 30:68 and 15:83 weight %. Mirrors of the «oxygen - free copper" brand were subjected to cleaning (surface shape N = 2; shape error ΔN = 0.5; optical purity class P = V). After five cleaning cycles, a thin layer of high-purity oxygen-free copper was evaporated in vacuum on the mirror, which noticeably improved the optical quality. On a series of mirrors after five cleaning cycles, according to the procedure (Ilyin and Filin (1992), we measured the optical damage, - the value of the laser radiation power density, at which a plasma torch is generated near the surface. This is the main characteristic of laser mirrors. The sample was dried for 5 min. The laser radiation power density (wavelength λ = 1.06 μm, pulse duration 30 ns) on the sample surface was consistently increased from 10 3 to 5  10 8 W/сm 2 . The threshold was determined at three points on the surface by gradually increasing the radiation exposure over an area of ~ 0.2 cm 2 until a stable flame appeared (measurement accuracy ±15%). Then, at a magnification of 80 х 160 х , the state of the mirrors was studied in areas with a different number of acting pulses of threshold intensity in the presence of a torch. As azeotrope, solvents with the energy of intermolecular bonds ("specific cohesion energy density") close to the energy of intermolecular bonds of the surface layer of the metal were studied. This made it possible to change the surface energy and determine changes in the energy characteristics of the mirror, primarily the ionization energy. 3. Results and discussion In Table 1, azeotropes are presented in ascending order of their Hildebrandt solubility parameter (δ) .

Table 1. Properties of solvents-azeotropes

Concentrations of azeotrope, weight %

Boiling point of azeotrope , ºC

Solubility parameter, δ , J -1/2 cm -3/2

Azeotrope

1. Ethanol - 2-butanone

50,8/49,2

74,3 62,2 57,7 57,6 56,2 64,5 79,0 73,7 36,5 36,4 47,4 55,2 54,1 44,0 41,3 47,1 48,1 49,0

22,9 20,4 20,2 20,0 19,7 19,3 18,8 18,3 18,0 18,0 17,3 16,7 16,1 16,0 15,9 15,3 15,1 14,9

2. Chloroform - acetone - ethanol 3. Cis-1,2 - dichloroethylene - acetone 4. 1,1-Dichloroethane - acetone 5. Carbon tetrachloride - acetone

47/ 34/29 mole% 6 7 ,4/32,6 mole%

70/30

11,5/88,5

6. Chloroform - acetone 7. Freon-112 - 2-butanone

63,5/36,5 mol.%

14/86

8. Carbon tetrachloride - 2-butanone 9. Freon-113 - methylene chloride - ethanol 10. Freon-114B2 - tert-butanol - methylene chloride 11. Freon-114B2 - tert-butanol - methylene chloride

67,5/32,5

49,5/49,5/1,0 53,6/2,2/44,2 63,0/0,5/36,5 76,1/21,1/2,8 86,4/12,0/1,6

12. Freon-113 - acetone - ethanol 13. Freon-113 - acetone - ethanol

14. Freon-113 - acetone 15. Freon-113 - ethanol

88,9/11,1 96,2/3,8

16. Freon-113 - tertiary butanol 17. Freon-114B2 - acetone 18. Freon-114B2 - tert-butanol

98/2

97,6/2,4

99/1