The transport of Ag in chemical vapour deposited β-SiC was studied using ion implantation. Silver ions were implanted into β-SiC by using an accelerator facility. Ion beams with energies of 93 and 161MeV were used to achieve deposition with peak concentrations of approximately 26wt% at depths of approximately 9 and 13μm, respectively. As-implanted samples were then annealed at 1500C for 210 or 480h. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. The Ag concentration profiles were determined by using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to characterize more fully the location and morphology of the Ag before and after annealing. The results showed that, to within the uncertainty of the measurement techniques, there was no Ag migration, via either inter- or intra-granular paths, for the times and temperature studied. Additionally, the Ag was observed to phase-separate within the SiC after annealing. The present results did not support the long held assumption that Ag release from CVD SiC, used for gas-reactor coated particle fuel, was dominated by grain boundary diffusion.

The Effect of Annealing at 1500C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide. H.J.MacLean, R.G.Ballinger, L.E.Kolaya, S.A.Simonson, N.Lewis, M.E.Hanson: Journal of Nuclear Materials, 2006, 357[1-3], 31-47