Hydrogen permeation resistance and characterization of Si–Al and Si–Zr composite sol oxide coating on surface of zirconium hydride

Abstract

The hydrogen permeation resistance of Si–Zr (SZ) and Si–Al (SA) composite sol oxide coating on zirconium hydride blocks (ZrH1.8) was studied. SZ and SA composite sol were prepared by sol–gel method. SZ and SA composite oxide coatings were prepared on the surface of ZrH1.8 (in situ oxidized or not) in turns by dip-coating and heat treatment. Hydrogen permeation of ZrH1.8 with and without composite oxide coating was compared. Hydrogen desorption experiments in thermal vacuum show that hydrogen permeation resistance of SA composite oxide coating is better than that of SZ, to a certain extent, which could decrease hydrogen thermal loss. Experimental results in the working condition show that the SA composite oxide coating can not only prevent hydrogen permeation, but also retard contact and reaction between CO2 and ZrH1.8 matrix, which could mitigate excessive oxidation of in situ oxide film. Differential scanning calorimetry and thermogravimetry (DSC–TG) analysis was performed to investigate the decomposition behavior of SA and SZ liquid sol in heat treatment process. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were employed to characterize the phase composition, surface and cross-section morphology of the coatings.