Preparation and characterization of SiO${}_2$/α-Al${}_2$O${}_3$ tritium permeation barriers at low temperature

A tritium permeation barrier on the surface of structural materials can effectively solve the problem of tritium fuel penetration and leakage. Herein, SiO${}_2$/α-Al${}_2$O${}_3$ ceramic coatings are prepared on 316L stainless steel through slurry spin coating method. Different particle sizes of α-Al${}_2$O${}_3$ powder are used to prepare three kinds of coatings. The particle sizes of α-Al${}_2$O${}_3$ used are 30 nm (sample 1), 200 nm (sample 2), and equal mass ratio of 30 nm and 200 nm mixed (sample 3), respectively. The results show that the ceramic coating is composed of α-Al${}_2$O${}_3$ and amorphous SiO${}_2$. The coating surface of sample 3 is uniform and compact and exhibits the best microstructure. Compared with samples 1 and 2, sample 3 has better thermal shock resistance. The binding strength of sample 3 is up to 69 N. Electrochemical hydrogen penetration tests indicate that SiO${}_2$/α-Al${}_2$O${}_3$ ceramic coating can effectively improve the electrochemical hydrogen resistance of 316 L stainless steel substrate. Sample 3 has the lowest stable hydrogen penetration current density and current density difference value. Although the hydrogen resistance of sample 3 is reduced after 50 thermal shocks, it is still better than that of the substrate. (© 2021 Wiley‐VCH GmbH)