Effects of Ar/O2 ratio on preparation and properties of multilayer Cr2O3/α-Al2O3 tritium permeation barrier

A multilayered Cr2O3/α-Al2O3 tritium permeation barrier coating containing a total of 10 nanoscale layers was prepared by radiofrequency magnetron sputtering without intentional heating. X-ray diffraction, Auger electron spectroscopy, and spherical aberration corrected transmission electron microscopy studies showed a multilayer structure and a Cr2O3 (104)/α-Al2O3 (104) coherent epitaxial growth. The effect of the Ar/O2 gas flow ratio (Λ) on the structure and properties of the Cr2O3/Al2O3 multilayer coating were investigated. The results show that the crystallinity of the α-Al2O3 phase increased with decreasing Λ. The mechanical properties, He+ ion irradiation tolerance, and corrosion resistance of the coating began to improve greatly when Λ was decreased to 1:1. The coating with Λ = 1:2 gave α-Al2O3 with the best properties, i.e., high nano-hardness (19.6 GPa), good corrosion resistance (icorr = 10 nA/cm2), and excellent irradiation resistance. The deuterium permeability of the Cr2O3/α-Al2O3 multilayer coating was also investigated.