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

94 4

The solubility parameter δ was estimated, using the formula

n n              ... ... ... ... 2 2 1 1 2 2 2 1 1 1      , i i n n n i i x V x V x V x V x V x V i x V x V

(1)

where V i - molar volume of the component; i – 1, 2,…, n ; x i - is the mole fraction of the component, determined from the expression

i M c

x



i

i M c

M c

M c 1

M c

i

     ... ... 2

n

(2)

,

1

2

i

n

where с i - is concentration of the component, weight %; M i - is the molecular weight. The optical stability of mirrors after treatment with azeotrope showed that the maximum damage values (1.0), close to those calculated for copper, were obtained for azeotropes: "freon-113 - methylene chloride - ethanol" (№ 9; δ = 18.0 J -1/2 ∙cm -3/2 ), "freon-114B2 (tetrafluorodibromoethane) - tert-butanol - methylene chloride" (№ 10 and № 11; δ = 17.3 J -1/2 ∙cm -3/2 and δ = 18.0 J -1/2 ∙cm -3/2 , respectively) and freon-114B2 - acetone (№ 17; δ = 15.1 J -1/2 ∙cm -3/2 ) (Fig. 1).

Fig. 1. Dependence of the optical resistance threshold of copper on the solubility parameter δ of the washing medium with the following content of pekcanifol resin in the contaminant: 1 - 75%; 2 - 60%; 3 - 45%; 4 - 30%; 5 - 15%.

The maximum damage when treated with an azeotrope of "freon-113 - acetone - ethanol" (№ 13) was obtained only for model contaminant containing 45 weight % peccanifol resin. The optical damage ~ 1.0 was fixed on all mirrors for all model contaminants, when cleaning with an azeotrope of "freon-114B2 - acetone". These results are due to the superposition of different factors, affecting the value of optical damage. This - is the removal during cleaning from the surface of contaminants that have a greater (compared to volumetric) absorption of radiation. The thermal explosion of contaminants leads to an anomalous decrease in the optical damage