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Registration Number

0222U000713, 0121U110372 , R & D reports

Title

Development of technological processes to improve the functional properties and life of modern and promising shell materials of fuel elements by treatment in controlled oxygen-nitrogen media. Within the framework of the complex project: "Improvement of operational properties and resource of modern and perspective shell materials of fuel elements by processing in the controlled gas environments"

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Head

Fedirko Viktor M., д.т.н.

Registration Date

18-01-2022

Organization

Physico-Mechanical Institute named after GV Karpenko of the National Academy of Sciences of Ukraine

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 The influence of chemical-thermal treatment of Zr-1% Nb alloy samples in oxygen-containing, nitrogen-containing and nitrogen-oxygen-containing gas mixtures on microhardness and structure of the near-surface metal layer was investigated. The effect of treatment in an oxygen-containing gaseous medium at different degrees of rarefaction (P = 1.33 Pa … 1.33×10-3 Pa) at a temperature of 580°C and a duration of 3 h on the parameters (hardness, microstructure) of the near-surface layer of Zr-1% Nb alloy samples is shown. It is revealed that depending on the degree of rarefaction of the technological environment there is a formation of the subsurface layer of metal with a certain hardness gradient. The activation energy of nitriding of Zr-1% Nb alloy by changing the constant of parabolic nitriding rate is determined. It is shown that the activation energy of nitriding of Zr-1% Nb alloy at nitrogen pressure 105 Pa in the temperature range 550…750°С is E = 1,907 kJ/mol. Zirconium oxynitride is formed on the surface of the zirconium alloy Zr-1% Nb as a result of interaction with nitrogen-containing gaseous medium according to the regimes P1 (P = 1.33×10-2 Pa) and P2 (P = 1.33×10-1 Pa). Oxynitriding revealed that the surface hardness of the Zr-1% Nb alloy samples under cooling at P = 1.33×10-2 Pa (mode P1) is Hs = 356 HV0.49 units of hardness, and then at P = 1.33×10-1 Pa (mode P2) - Hs. = 529 HV0.49. Differences in the formation of the hardness gradient in the near-surface layer of Zr-1% Nb alloy depending on the degree of rarefaction of the oxidizing medium during cooling are shown.

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Baranetsʹkyy Volodymyr S
Kordyukevych Myron O.
Kravchyshyn Taras M.
Kukhar Ivan S.
Luk'janenko Oleksandr Не.
Trush Vasylʹ S
Fedirko Viktor M.

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2022-03-09