The Effect of Hydrogen Irradiation on the Structure and Properties of Cr2O3/Al2O3-Based Detonation Coatings

This study investigates the effect of high-temperature hydrogen exposure on the structure and properties of Cr2O3/Al2O3-based detonation coatings deposited on AISI 316L stainless steel. Bilayer and gradient coatings were exposed to hydrogen at 1000 °C for 3, 4, and 5 h and subsequently characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), surface profilometry, and thermal desorption spectroscopy (TDS). One independent specimen was examined for each combination of coating architecture and hydrogen exposure duration. Therefore, the present study was designed as an exploratory comparative investigation rather than a statistically powered study. The principal α-Al2O3 and Cr2O3 phases remained detectable after all exposure durations, indicating preservation of the main oxide phases. SEM/EDS analysis revealed microcracks, local defects, and heterogeneous surface regions, with more pronounced localized damage in the bilayer coatings. The Ra values of the bilayer coatings were 1.385, 0.833, and 1.207 μm after 3, 4, and 5 h, respectively, whereas the corresponding values for the gradient coatings were 1.049, 1.337, and 1.049 μm. The minimum Ra of 0.833 μm after 4 h in the bilayer coating coincided with SEM/EDS evidence suggesting local coating damage and possible thinning. TDS showed the most intense hydrogen desorption for the gradient coating after 3 h. Overall, the observed results suggest that coating architecture influences surface evolution and hydrogen-retention behavior under the investigated high-temperature hydrogen exposure conditions.