Surface modification of thick SiC gradient coatings on doped graphite under long pulse plasma irradiation

Selection of candidate plasma facing materials (PFM) in experimental fusion device is very important due to its direct influence on the plasma performance. To meet the requirements of high power and steady state operation, one kind of multi-element doped graphite GBST1308 (1%B4C, 2.5%Si, 7.5%Ti) with thick SiC gradient coatings was chosen as the main limiter materials for the HT-7 device. Surface modification of the SiC coatings on doped graphite under long pulse plasma irradiation was carefully investigated by examining the surface morphology, structure, and atomic composition. The obtained results showed the crystal structure of SiC was replaced by lamellar matter or film with plentiful oxygen and some other elements existed in the surface of graphite tiles after the plasma irradiation.