The use of coatings on SiC/SiC fuel cladding offers thepromise of decreased aqueous dissolution and greaterhermiticity, while realizing the promise of SiC/SiC as a fuelcladdingmaterial. In this work, SiC/SiC and CVD-SiCsamples with candidate coatings were irradiated to a neutronfluence of 4.8 × 10~(20) n/cm~2 >0.1 MeV at 290-340°C in aninert environment to examine their behavior underirradiation. Samples coated with Cr or a multilayered Cr-CrN coating exhibited significant cracking. Samples coatedwith CrN showed very little cracking, and TiN coatedspecimens did not crack at all. XRD measurements showedlattice expansion of 0.5-0.6% in the SiC substrates, but nosignificant lattice expansion in the coatings. TEMinvestigation showed cavity swelling in the Cr coatings,possibly a result of impurities introduced during the coatingprocess, and the likely cause of the observed cracking. Thelow crack density observed on the TiN and CrN coatingsindicate either good bond strength, or very good stressrelaxation due to irradiation creep.
展开▼
