Search Results (5)

How to solve hydrogen embrittlement (HE) is a key issue that urgently needs to be addressed in the hydrogen energy industry. The use of hydrogen barrier coatings can effectively reduce the occurrence of HE. In this article, we utilized the epoxy resin (ER) as the base coating and the graphene (GN) and the silicon carbide (SiC) as the additives to prepare the (GN-ER)/(SiC-ER)/(GN-ER) sandwich structure composite hydrogen barrier coatings by the spin coating method and investigated the effect of coating composite ways on the hydrogen barrier performance. The GN-ER and the SiC-ER are used as the hydrogen barrier layer and the hydrogen capture layer, respectively, in order to improve the hydrogen barrier performances jointly. The XRD and the SEM were used to characterize their phase compositions and microstructures, and the hydrogen barrier performances were analyzed by the electrochemical hydrogen permeation curves. The adhesive strength was characterized through the pull-out method. Compared to the single-layer and the double-layer structures, sandwich structures can effectively enhance the hydrogen barrier performance of the coatings, such as the relatively low electrochemical hydrogen diffusion coefficient (D_t, 3.88 × 10⁻⁸ cm²·s⁻¹), the relatively high permeation reduction factor (PRF, 59) and adhesive strength (10.9 MPa). This research may provide a theoretical basis for improving the hydrogen barrier performance of coatings. The (GN-ER)/(SiC ER)/(GN-ER) sandwich structures composite hydrogen barrier coatings can be expected to be used in the field of safe hydrogen storage and transportation. Full article

The permeation of tritium from secondary neutron source rods in nuclear power plants presents a significant and unavoidable safety concern both for internal equipment and the external environment. This study primarily explores two feasible strategies for tritium permeation barriers: coating stainless steel surfaces with tritium permeation barrier (TPB) materials and utilizing materials with excellent tritium absorption properties. Through external ion irradiation tests, a comparative analysis was conducted on the tritium permeation performance, morphology, and nanohardness changes in two tritium-resistant designs, specifically Cr₂O₃/Al₂O₃ composite coatings and a zirconium-based tritium-absorbing material under varying irradiation doses. The results indicate that both approaches exhibit exceptional radiation resistance, maintaining an effective tritium permeation reduction factor (PRF) even after irradiation. Full article

The present work attempted to produce thick zirconia coatings formed by micro-arc oxidation as a hydrogen permeation barrier on zirconium hydride alloy. A novel multiphase zirconia coating was achieved, exhibiting superior hydrogen permeation barrier performance. The growth dynamics, formation mechanism, and phase evolution behavior of thick zirconia coatings were explored, and the hydrogen permeation barrier performance was evaluated by means of vacuum dehydrogenation experiment. The hydrogen desorption quantity was monitored by analyzing pressure changes with a quadruple mass spectrometer (QMS). Experimental results show that the multiphase coatings were composed of monoclinic ZrO₂ (m-ZrO₂), tetragonal ZrO₂ (t-ZrO₂), and a trace of cubic ZrO₂ (c-ZrO₂). The coatings were generally divided into a dense and uniform inner, intermediate layer, and a porous top layer. The quantitative analysis indicates an increased amount of m-ZrO₂ toward the coating surface and an increased amount of t-ZrO₂ toward the oxide/metal interface. This novel multiphase thick zirconia coating can noticeably improve hydrogen permeation resistance, and the permeation reduction factor (PRF) value is improved by nearly 13 times compared with bare zirconium hydride. It is demonstrated that hydrogen desorption is retarded to some extent in the presence of thick zirconia coating. Hydrogen desorption of the sample with ceramic coating started at 660 °C, which was apparently higher than that of the sample without coating. Full article

Hydrogen permeation barrier plays an important role in reducing hydrogen loss from zirconium hydride matrix when used as neutron moderator. Here, a composite nitride film was prepared on zirconium hydride by in situ reaction method in nitrogen atmosphere. The phase structure, morphology, element distribution, and valence states of the composite film were investigated by XRD, SEM, AES, and XPS analysis. It was found that the composite nitride film was continuous and dense with about 1.6 μm thickness; the major phase of the film was ZrN, with coexistence of ZrO₂, ZrO, and ZrN_0.36H_0.8; and Zr-C, Zr-O, Zr-N, O-H, and N-H bonds were detected in the film. The existence of ZrN_0.36H_0.8 phase and the bonds of O-H and N-H revealed that the nitrogen and oxygen in the film could capture hydrogen from the zirconium hydride matrix. The hydrogen permeation performance of nitride film was compared with oxide film by permeation reduction factor (PRF), vacuum thermal dehydrogenation (VTD), and hydrogen permeation rate (HPR) methods, and the results showed that the hydrogen permeation barrier effects of nitride film were better than that of oxide film. The zirconium nitride film would be a potential candidate for hydrogen permeation barrier on the surface of zirconium hydride. Full article

Aluminum containing M_n+1AX_n (MAX) phase materials have attracted increasing attention due to their corrosion resistance, a pronounced self-healing effect and promising diffusion barrier properties for hydrogen. We synthesized Ti₂AlN coatings on ferritic steel substrates by physical vapor deposition of alternating Ti- and AlN-layers followed by thermal annealing. The microstructure developed a {0001}-texture with platelet-like shaped grains. To investigate the oxidation behavior, the samples were exposed to a temperature of 700 °C in a muffle furnace. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) depth profiles revealed the formation of oxide scales, which consisted mainly of dense and stable α-Al₂O₃. The oxide layer thickness increased with a time dependency of ~t^1/4. Electron probe micro analysis (EPMA) scans revealed a diffusion of Al from the coating into the substrate. Steel membranes with as-deposited Ti₂AlN and partially oxidized Ti₂AlN coatings were used for permeation tests. The permeation of deuterium from the gas phase was measured in an ultra-high vacuum (UHV) permeation cell by mass spectrometry at temperatures of 30–400 °C. We obtained a permeation reduction factor (PRF) of 45 for a pure Ti₂AlN coating and a PRF of ~3700 for the oxidized sample. Thus, protective coatings, which prevent hydrogen-induced corrosion, can be achieved by the proper design of Ti₂AlN coatings with suitable oxide scale thicknesses. Full article