Manufacturing and characterization of porous SiC for flow channel inserts in dual-coolant blanket designs

摘要

SiC is the primary candidate for the flow channel inserts in dual-coolant blanket concepts. Porous SiC ceramics are attractive candidates for this non-structural application, since they can satisfy the required properties through a low cost manufacturing route, compared to SiCr/SiC. This work shows first results of the manufacturing of porous SiC ceramics prepared with different amounts of Y_2O_3 and Al_2O_3 as sintering additives. C powders were used as pore-formers by their burnout during oxidation after sintering. Comparison of microstructure, porosity, flexural strength, thermal and electrical conductivity and corrosion under Pb-15.7Li of porous SiC without and with sintering additives is presented. The addition of 2.5 wt.% of Y_2O_3 and Al_2O_3 improves the mechanical properties, and reduces the thermal and electrical conductivity down to reasonable values. Preliminary corrosion tests under Pb-15.7 Li at 500℃ show that the absence of a dense coating on porous SiC leads to poor corrosion behavior.