The atomic radius of hydrogen and its isotopes is very small, making them easy to diffuse and permeate in materials. Once they permeate into the materials of nuclear reactor components, they will cause significant damage to the materials, which can lead to serious economic loss and even serious reactor safety accidents and radioactive pollution. The solution is to set a permeation barrier on the permeation path of hydrogen and its isotopes, and to prepare a hydrogen / deuterium / tritium permeation barrier coating on the surface of the related nuclear reactor components. According to the service environment of hydrogen / deuterium / tritium permeation barrier coatings, high requirements have been put forward for their performance. The coatings must have a high permeation reduction factor (PRF), self-healing ability, good thermal shock resistance, low irradiation activation, good radiation resistance, and good compatibility with liquid coolants. In addition, the coating should also be able to be easily prepared on the surface of the complex nuclear reactor components, with a potential for engineering applications. Oxides and their composite coatings have many advantages, such as high melting point, stable chemical properties, relatively simple preparation process, and excellent hydrogen isotope permeation barrier properties;therefore, they have become a hot spot in the research field of hydrogen / deuterium / tritium permeation barrier coatings, especially α-Al2 O3 coatings. The preparation processes of α-Al2 O3 and its composite coatings by the hot-dip aluminizing (HDA), pack cementation (PC)and electrochemical deposition (ECA)have been reported in industrial application. All the three methods have good feasibility for large-scale production. Moreover, the research on the permeation mechanism of hydrogen isotopes mainly involves two key limiting steps in the process, surface adsorption and intragranular diffusion. The adsorption mechanism of hydrogen isotopes on the surface of coating materials is reflected in the permeation pressure index (n). n for hydrogen isotopes in metal materials is 0. 5, indi-cating that hydrogen isotopes are dissolved into atoms, and then the hydrogen atoms diffuse in the metal lattice. It is found that n = 1 for hydrogen isotopes in ceramic materials, indicating that hydrogen isotopes are adsorbed in a molecular state and diffuse in the ceramic in molecular form. In addition, the deuterium permeation test PRF value of Al2 O3 coating becomes smaller after irradiation, and the hydrogen barrier performance of Al2 O3 deteriorates rapidly due to the irradiation damage. In this paper, we briefly introduce the latest research progress on the selection of hydrogen / deuterium / tritium permeation barrier coating materials, the exploration of the preparation technology, details of the experimental research on the hydrogen isotope permeation of the coatings, and the hydrogen isotope permeation mechanism and its irradiation effect. The developing direction of using hydrogen / deuterium / tritium permeation barrier coatings on the surface of related nuclear reactor components is also highlighted. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
