A novel low-temperature approach for fabricating α-Al₂O₃-based ceramic coating as tritium permeation barrier

Highlights: • A new low-temperature method was developed for fabricating α-Al₂O₃ based coating. • α-Al₂O₃ based coating was successfully fabricated on a steel substrate at 500 °C. • The resulted coating was rather compact, without pores and cracks. • The coating adhered to the substrate firmly with a considerable binding force. • This method is cost-effective, facile, and applicable to complex geometry. - Abstract: α-Al₂O₃-based coatings have attracted great interest as promising tritium permeation barrier used in the D-T fusion reactor system. However, it is still difficult to fabricate α-Al₂O₃ coatings at a low temperature that can be endured by the steel substrate. Herein, thermal-chemical reaction method was developed for the fabrication of α-Al₂O₃-based coatings. α-Al₂O₃/AlPO₄ composite coating was successfully formed on the steel substrate at 500 °C. The resulted coating was uniform and compact without presence of pores and cracks. The binding strength of the coating was tested and the result indicated its good adherence to the substrate. Moreover, the coating thickness could be easily controlled. The low-temperature approach developed is expected to provide a new platform for fabricating α-Al₂O₃-based coatings as tritium permeation barrier. This approach is also applicable to the fabrication of other ceramic coatings.