Objective Injection and production pipes in salt cavern hydrogen storage face severe risks of hydrogen embrittlement and corrosion. There is an urgent need to develop highly effective hydrogen barrier coatings. This study aims to systematically evaluate and compare representative coatings to guide the selection and design of protection technologies suited to the salt cavern hydrogen storage environment.

Methods TiN, AlCrN, and (TiAlCrSiY)N coatings were prepared on N80 steel via multi-arc ion plating. Their hydrogen permeation resistance was systematically assessed using a Devanathan-Stachurski double-electrolytic cell under two hydrogen charging modes (electrochemical monitoring in liquid and gas phases). Corrosion resistance was evaluated through electrochemical polarization curve tests. The microstructures and properties of the coatings were characterized by scanning electron microscope (SEM) and digital microscopy. By comparing the comprehensive protective performance of TiN, AlCrN, and (TiAlCrSiY)N coatings, differences in underlying mechanisms were analyzed to provide a scientific basis for selecting and designing hydrogen barrier coatings for salt cavern hydrogen storage environments.

Results The AlCrN coating demonstrated the best overall performance, featuring the densest, flattest surface, fewest defects, highest hardness, and strongest bonding. Although the (TiAlCrSiY)N coating exhibited superior corrosion resistance due to the synergistic effect of multiple elements, it had numerous surface agglomerates, micro-defects, and the weakest bonding among the three coatings. Hydrogen permeation tests showed that AlCrN provided the most effective barrier, reducing the effective diffusion coefficient by 83.68％ compared to the N80 substrate, with hydrogen barrier efficiencies of 99.23％ in the gas phase and 84.76％ in the liquid phase. All three coatings—TiN, AlCrN, and (TiAlCrSiY)N—offered good hydrogen barrier properties and enhanced substrate strength and corrosion resistance. The test and analysis results indicated that coating microstructure compactness primarily determined hydrogen barrier and mechanical properties, while corrosion resistance depended mainly on chemical composition.

Conclusion In developing hydrogen barrier coatings for salt cavern hydrogen storage, priority should be given to achieving a dense, low-defect structure through process optimization, followed by composition optimization to enhance chemical stability. Simultaneously improving corrosion resistance and mechanical properties is crucial for ensuring the safe operation of salt cavern hydrogen storage facilities.