Design, Optimization and Performance Testing of Self-Healing Tritium Permeation Barriers

Tritium permeation barriers (TPBs) are essential to reduce the tritium permeation through blanket structural materials and cooling tubes. The pores and cracks are the most important problem of thermally sprayed TPBs. Irradiation swelling is another serious problem in NiAl which used as adhesive layer in traditional Al₂O₃ coatings. A self-healing coating TiC+mixture (TiC/Al₂O₃)+Al₂O₃ without NiAl had been designed and manufactured by our group. It can cure 90% porosity after a certain heat treatment under normal atmosphere. The adhesive strength is as good as the traditional coating NiAl+Al₂O₃. The thermal shock cycles were 300, 210 and 123 at 600°C, 700°C and 800°C respectively. On the basis, the self-healing treatment parameters were explored further, and a more effective and efficient treatment was found. Structural design and component design were also researched. The thermal shock results showed that the thicknesses of TiC layer and mixture (TiC/Al₂O₃) layer both had a significant effect while the Al₂O₃ layer hadn’t. The interface of TiC and mixture (TiC/Al₂O₃) was most easily damaged, so other proportion of TiC and Al₂O₃ was applied, and several kinds of new coatings were designed, manufactured and tested. A better coating has been found, and it will probably be a good candidate for TPBs in fusion reactors.