Objective To address the severe risks of hydrogen embrittlement and corrosion facing injection-production tubing in salt cavern hydrogen storage, the development of high-efficiency hydrogen barrier coatings is imperative. Consequently, a systematic evaluation and comparison of representative coatings is crucial for the selection and design of protective technologies suitable for such environments.
Methods Three types of nitride coatings were prepared on N80 steel substrates using multi-arc ion plating technology. The hydrogen permeation resistance of each coating was systematically evaluated under both liquid-phase and gas-phase hydrogen charging modes using a Devanathan-Stachurski dual electrochemical cell. Their corrosion resistance was assessed via electrochemical polarization curves. The microstructure and mechanical properties of the coatings were characterized by scanning electron microscopy (SEM), digital microscopy, microhardness testing, and micro-scratch testing. This study provides a comprehensive analysis and comparison of the protective performance and underlying mechanisms of the three coatings, offering a scientific basis for material selection and design in salt cavern hydrogen storage environments.
Results The AlCrN coating exhibited the best overall performance, featuring the densest, flattest surface with the fewest defects, and it demonstrated the highest hardness and the strongest adhesion. Although the (TiAlCrSiY)N coating showed optimal corrosion resistance due to the synergistic effect of its multiple elements, it suffered from numerous surface agglomerates and micro-defects, resulting in the weakest adhesion among the three. Hydrogen permeation tests revealed that, regardless of the charging mode, the AlCrN coating provided the most effective barrier against hydrogen. Compared to the bare N80 substrate, it reduced the effective diffusion coefficient by 83.68％, with hydrogen blocking efficiencies reaching as high as 99.23％ (gas-phase) and 84.76％ (liquid-phase).
Conclusion A comprehensive evaluation confirms that all three nitride coatings provide good hydrogen resistance and other beneficial properties such as corrosion resistance and adhesion. The microstructural density of the coatings is the primary factor determining their hydrogen permeation resistance and mechanical properties, whereas corrosion resistance is principally governed by chemical composition. Future development of hydrogen barrier coatings for salt cavern hydrogen storage should prioritize process optimization to achieve low-defect, dense microstructures, followed by compositional optimization to enhance chemical stability and concurrently improve corrosion resistance and mechanical properties. This approach holds significant engineering guidance for ensuring the safe operation of salt cavern hydrogen storage infrastructure.
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