The Influence of Hydrogen on the Process of Changing the Shape of Palladium Plates at a Temperature above at the Critical Temperature
O. M. Lyubymenko
Donetsk National Technical University, 2 Shybankov Sqr., UA-85300 Pokrovs’k, Ukraine
Received: 16.01.2023; final version - 23.02.2023. Download: PDF
The paper describes and analyses a video recording of an experiment to study the change in shape of a palladium plate at a temperature of 350°C. The experiment was performed for a plate covered on one side with a copper film that does not allow hydrogen to pass through and does not affect the amount of deformation. Sample saturation and degassing was performed in three stages. Already after the first stage, a gradient alloy of palladium with hydrogen $\alpha$-PdH$_{n}$ was obtained, therefore, at the next stage, the hydrogen content in the PdH$_{n}$ alloy was gradually increased by $\Delta n$ = $n$ = 0.00657 = const, from 0.00167 to 0.02068 N/Pd. From the video recording, it was found that the bending of the plate in the process of saturation and degassing for the $\alpha$-PdH$_{n}$ alloy occurs in two stages: the first stage is the achievement of the maximum bending; the second stage is straightening the plate and returning to the initial state. It was experimentally determined for the first time that upon saturation of the $\alpha$-PdH$_{n}$ alloy, when the hydrogen content increased by $\Delta n$ = $n$ = 0.00657 N/Pd in palladium, the value of the maximum bending of the plate decreased, but the bending of the plate was always almost completely reversible. During the course of the degassing process, when the hydrogen content changed by $\Delta n$, the maximum bends occurred in the opposite direction, but had a slight increase and were also almost completely reversible. The process of forming the maximum bending of the plate for the gradient alloys $\alpha$-PdH$_{0,00657}$, $\alpha$-PdH$_{0,0132}$, $\alpha$-PdH$_{0,02068}$ is due to the diffusion transport of hydrogen, the redistribution of internal stresses in the plate during its bending (straightening) and the corresponding rearrangement of the concentration field of hydrogen, which changes the internal conditions of diffusion transport of hydrogen into the layers of the $\alpha$-PdH$_{n}$ alloy, which have different physical properties (lattice period, Young's modulus) than pure palladium.
Key words: hydrogen, palladium, diffusion, gradient alloy, saturation, degassing, concentration, hydrogen stresses.
URL: https://mfint.imp.kiev.ua/en/abstract/v45/i02/0263.html
DOI: https://doi.org/10.15407/mfint.45.02.0263
PACS: 62.20.-x, 66.30.jp, 81.05.Bx, 81.40.Lm
Citation: O. M. Lyubymenko, The Influence of Hydrogen on the Process of Changing the Shape of Palladium Plates at a Temperature above at the Critical Temperature, Metallofiz. Noveishie Tekhnol., 45, No. 2: 263—274 (2023) (in Ukrainian)