Optimization of alumina tritium permeation barrier with consideration of the thickness and the surface coverage

Alumina is considered as one of the most promising candidates for tritium permeation barrier. Coating preparation parameters such as the thickness and the surface coverage both affect the hydrogen isotope resistant performance of TPBs. Alumina coatings with thickness in the nanometric scale are considered in this work. Reduced thickness in the coatings leads to an improvement in the thermal conductivity and the reduction of mismatch problems with the substrate due to differences in the thermal expansion coefficients. Alumina coatings with different thickness were prepared on differentiated manufactured substrate by radio frequency magnetron sputtering with varying sputtering time. Deposited alumina layers are maximal 104.2 nm in thickness. Gasdriven permeation experiments have been performed to investigate the deuterium permeation behavior of the coating samples. It is noted that the alumina coating with only approximately 100 nm in thickness whose permeation reduction factor could achieve 1784 at 823 K and maintain its excellent performance at elevated temperatures, which indicates that the coating at nanometer scale with high surface coverage is capable of possessing extraordinary hydrogen permeation resistance property.