Microstructure and peeling behavior of MOCVD processed oxide insulator coating before and after ion beam irradiation

The mechanical durability and soundness of the several oxide coating materials used as the electrical insulator and tritium permeation barrier are important design parameters on an advanced liquid breeding blanket system. We tried to investigate the adhesion strength evaluation due to the peeling behavior on the MOCVD processed multilayered oxide coating (Er₂O₃/Y₂O₃) on the stainless steel (SUS) substrate before and after Cu²⁺ ion beam irradiation using the nano-scratch tester. The adhesion strength of the coating material was able to estimate easily from the scratch trace and scratch stress, and the nano-scratch test was suitable method to evaluate the mechanical durability and soundness. After the Cu²⁺ ion beam irradiation, the adhesion strength was decreased with increasing the displacement per atom (dpa). The adhesion strength degradation by the Cu²⁺ ion beam irradiation was caused by the embrittlement of the thicker and amorphous Fe-(Y)-O interlayer formation between Y₂O₃ buffer layer and SUS substrate based on the displacement damage dose effect.