Investigation of hydrogen isotope permeation through F82H steel with and without a ceramic coating of Cr2O3–SiO2 including CrPO4 (out-of-pile tests)

Ceramic coating on structural materials has been considered to be used as a tritium permeation barrier for fusion power plants. In the present study, a series of hydrogen and deuterium permeation experiments was performed for ferritic F82H steel with and without a ceramic coating of Cr2O3–SiO2 including CrPO4. First, experiments were made on the permeability of F82H steel without coating at 300–600 °C in an atmosphere of 100–1000 Pa hydrogen and deuterium. The measured values of diffusion coefficient, permeability and solubility were in good agreement with those published previously. Next, experiments were performed on the permeability of F82H steel with the coating at 400–600 °C in an atmosphere of 1000–1500 Pa deuterium, and the permeation reduction factor (PRF) of the coating was determined. The obtained PRF at 600 °C was about 400, which is of the same order of magnitude as the PRF value of about 1000 previously evaluated for the same coating on an SS316 substrate. A significant decrease in the PRF (down to about 4%) was observed, when the sample temperature was lowered from 600 to 400 °C.