The effect of current density on the anodic oxidation hydrogen barrier film on ZrH1.8 surface

Abstract

To improve the density and hydrogen barrier performance of the anodic oxide layer on the surface of ZrH1.8, anodization of the ZrH1.8 substrate was performed under a constant current mode. In an alkaline electrolyte environment, the film growth process was investigated under varying current densities (233, 280, 326, and 373 A/m2). The morphology, phase structure, thickness, and adhesion of the film were analyzed. The hydrogen barrier properties of the films at different current densities were evaluated through dehydrogenation experiments. The barrier properties of the film were further analyzed via electrochemical tests. The results indicate that zirconia hydrogen barrier coatings with thicknesses of 12.77, 18.74, 23.16 and 22.26 µm can be fabricated on the surface of ZrH1.8 at different current densities. The coatings contain both monoclinic zirconia (M-ZrO2) and tetragonal zirconia (T-ZrO2) phases, among which M-ZrO2 prevails. The current density has no substantial effect on the phase composition of the coatings. At a current density of 280 A/m2, a more homogeneous and compact film with superior dense adhesion and the thickness of 18.74 µm was fabricated on the ZrH1.8 surface. The hydrogen permeation temperature reached 660 °C, demonstrating a relatively good hydrogen barrier performance.