Determination of permeation properties of hydrogen gas in sealing rubbers using thermal desorption analysis gas chromatography

Permeation properties of hydrogen gas (H2) into nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), and fluoroelastomer (FKM) which are the strong candidates for sealing material in H2 energy infrastructures, was quantified using a thermal desorption analysis gas chromatography (TDA GC) and a self-developed diffusion-analysis program. The samples were charged with H2 in a high-pressure chamber for 24 h then decompressed into atmosphere, and the mass of H2 released from the sample was measured as a function of elapsed time after decompression. The developed program calculated the total charging amount C0 and diffusivity D, which were then used to calculate the H2 solubility S and permeability P for variation of pressure. The samples were polymerized with and without carbon black (CB) filler in cylindrical shapes with different diameters. There was no appreciable pressure up to 12 MPa or diameter dependence investigated in this study on D, S and P. NBR and EPDM showed dual hydrogen diffusion with fast and slow diffusion behaviors caused by CB, whereas FKM showed a single diffusion behavior. The determined D are Dfast, NBR = (1.55 ± 0.28) × 10–10 m2/s, Dslow, NBR = (3.1 ± 0.5) × 10–11 m2/s, Dfast, EPDM = (3.65 ± 0.66) × 10–10 m2/s, Dslow, EPDM = (3.3 ± 0.5) × 10–11 m2/s, DFKM = (7.7 ± 0.8) × 10–11 m2/s. It appeared that the filler contributes to increase S and decrease D. The uncertainty analysis against the evaluated data was carried out, too, in order that the method could be applicable as a standard test for the permeation properties of various polymer membranes.

Comparison of Hydrogen Thermal Desorption Analysis Curves of Electron-Irradiated F82H and Creep-Ruptured Pure Fe Obtained by Experiments and Simulations

Herein, we compared thermal desorption analysis (TDA) curves obtained by conducting experiments and simulations. In addition, we discussed the validation of our simulations and trapping sites of hydrogen atoms. In as-received F82H, when the samples contained solute atoms, grain boundaries, dislocations, and precipitates, the experimental curve corresponded to the simulated curve. In positron annihilation lifetime (PAL) measurements, di-vacancies were detected in the electron-irradiated F82H. When we changed the growth and the concentration of vacancy-type defects during temperature increase using the rate theory, the simulation results agreed with experiment results. In creep-ruptured Fe, only dislocations were detected by the PAL measurements. However, the existence of a type of defect, which was related to grain boundaries, must be assumed to fit the simulation curve to the experimental one. In the next step, the diffusion of hydrogen atoms on grain boundaries should be added to simulation program.

DEUTERIUM TRAPPING IN TUNGSTEN IRRADIATED WITH DEUTERIUM PLASMA AT HIGH TEMPERATURES

This work was attended to the study of the accumulation of deuterium, also to the investigation of the process of capture of deuterium in tungsten samples upon irradiation with a plasma beam. It was shown that after irradiation on the surface, a change in the surface is observed as the development of the relief as a result of nonuniform etching of the surface. The degree of change in the relief and structure of the surface layer of the irradiated samples depends on the irradiation temperature. The accumulation of deuterium tungsten under irradiation with deuterium plasma was studied. The conducted thermal desorption analysis of tungsten samples irradiated with deuterium plasma showed that the tungsten surface is saturated with deuterium. The data obtained by the method of emission spectrometry and thermal desorption spectrometry showed that the majority of the captured deuterium accumulates at a depth under the 7 μm.