Investigation of Microstructure and Hydrogen Barrier Behavior in Epoxy Resin-Based Ceramic/Graphene Composite Coatings

This study addresses the critical challenges of hydrogen permeation and embrittlement in metallic pipelines for hydrogen storage and transportation by developing an epoxy resin-based composite coating with enhanced hydrogen barrier properties. Using cold spray technology, the fabricated coatings with controlled 250–320 μm thicknesses incorporating graphene/ceramic composite particles uniformly dispersed in the epoxy matrix. Microstructural characterization revealed dense morphology and excellent interfacial bonding. Electrochemical hydrogen charging tests demonstrated remarkable hydrogen permeation reduction, showing a strong positive correlation between coating thickness and barrier performance. The optimal 320 μm-thick coating achieved a hydrogen content of only 0.28 ± 0.09 ppm, representing an 89% reduction compared to that in uncoated substrates. The superior performance originates from the Al2O3/SiO2 networks providing physical barriers, graphene offering high-surface-area adsorption sites, and MgO chemically trapping hydrogen atoms. Post-charging analysis identified interfacial stress concentration and hydrogen-induced plasticization as primary causes of ceramic particle delamination. This work provides both fundamental insights and practical solutions for designing high-performance protective coatings in long-distance hydrogen pipelines.