Corrosion resistance properties and hydrogen embrittlement protection efficiency of single-layer and multi-layer metal and ceramic films deposited on SS316L substrates

Hydrogen is a promising source of clean energy. However, the tanks used to store hydrogen fuel are prone to hydrogen embrittlement and are thus at risk of stress cracking and catastrophic failure. Accordingly, this study deposited single-layer and double-layer Zr, Al, SiO₂, Al₂O₃, Al@Al₂O₃, and Al@SiO₂ films on 316L stainless steel substrates and examined their feasibility as protective coatings by measuring their anti-corrosion properties and hydrogen permeation currents. The results showed that the single-layer Al₂O₃ film had a higher corrosion resistance than the single-layer SiO₂ film and bare 316L substrate. Among all the coatings, the Al@Al₂O₃ double-layer coating exhibited the highest protection efficiency of 95 %. Moreover, it showed the lowest hydrogen penetration current density (1.08 x 10⁻³ A/cm²), the longest hydrogen embrittlement time (16000 s), and the lowest hydrogen content (0.008 mol/cm³). In other words, the Al@Al₂O₃ double-layer coating combined superior corrosion resistance with excellent hydrogen permeation suppression. Consequently, it is a promising material for enhancing the safety and longevity of hydrogen storage tanks in practical applications.