The Study On Typical Oxide Hydrogen-isotopes Permeation Barriers

In the fields of nuclear fusion energy and hydrogen energy related, hydrogen isotopes permeation barriers are used to impede the permeation and leakage of hydrogen isotopes In this study, several oxide coatings, such as Er2O3 coatings, Al2O3 coatings, Y2O3 coatings and Cr2O3 coatings were selected for studying on the permeation reduction factor and stability in high-temperature hydrogen environment. The results are as follows.The D-PRF of 0.2 μm Er2O3 coatings from magnetron sputtering was 10-30 at 600-300℃. However, as a result of deuterium invasion, the Er2O3 coatings begun to peel off from substrates and the D-PRF decreased with increasing coating thickness. When the coating thickness reached 0.8 μm, the coatings had failed to impede the deuterium permeation.The D-PRF of 0.2 μm Er2O3 coatings from sol-gel was 60-80 at 600-300℃ and remained stable after five deuterium permeations which were performed at 600-300℃. After 128 h annealing in hydrogen at 700℃, the grains of coatings did not grow, the morphology, phase composition, cohesion and nano hardness of coatings also did not change obviously. However, the resisitivity decreased from 8.6×109 Ω·m to 3.3×106 Ω·m, which might be the result of formation of impurity level.The D-PRF of 0.2 μm Al2O3 coatings, which were annealed at 600℃ in vacuum, was 30-50 at 600-300℃. The D-PRF did not increase proportionately when the coating thickness increased from 0.2 μm to 1.6 μm, which might be ascribed to the higher energy barriers on the surface of Al2O3 coatings. When the coatings were annealed at 700℃ in vacuum, the D-PRF reached 50-80 at 600-300℃, which might be the result of grain growth of coatings. But, because the formation of MnCrO3 and Mn3O4 provided short-cut for deuterium permeation, the D-PRF decreased to 8 when the annealing temperature of coatings reached 800℃In terms of Y2O3 coatings, with increasing annealing time in hydrogen, the preferred orientation changed gradually from (222) to (400), the adhesion decreased, the color of the coatings changed from brown to gray, the resisitiviy decreased about two orders of magnitude from 8.2×109 Ω·m and reached stable in the end.The D-PRF of 0.2 μm Cr2O3 coatings was 6-12 at 600-300℃. After deuterium permeation at 600-300℃, the coatings cracked. Because the deuterium atoms could permeate easily through cracked area, the D-PRF decreased. As a result of deuterium invasion, the original preferred prientation was destroyed, the morphology appeared looser and the nano-hardness decreased with increasing annealing time.Through the study on permeation reduction factor and stability in high-temperature hydrogen atmosphere of several typical oxide coatings, the data on these several typical oxide coatings were further perfected. The influence factor and mechanism of D-PRF of oxide coatings were investigated carefully. The stability of oxide coatings in hydrogen isotopes at high-temperature were also been studied systematically. This paper is beneficial to the manufacture of hydrogen isotopes permeation barriers with high performance and high stability.