Characterization and thermomechanical assessment of a SiC-sandwich material for Flow Channel Inserts in DCLL blankets

Abstract

Flow Channel Inserts (FCIs) are key elements in the high-temperature Dual Coolant Lead Lithium (DCLL) blanket, since they insulate electrically the flowing PbLi to avoid MHD effects and protect the steel structure from the hot liquid metal. SiC-based materials are main candidates for high-temperature FCIs, being a denseporous SiC-based sandwich material an attractive option. The present work is focused on the development of such a SiC-based material.

On the one hand, in order to assess the suitability of the concept for FCIs, the main results of a stress analysis, MHD and heat transfer simulations are summarized. On the other hand, the experimental production of the SiC-based material is addressed, where the porous SiC core is manufactured from SiC powder by two different techniques: uniaxial pressing and gelcasting. The porosity is introduced using graphite spherical powder as a sacrificial template. After the production of the porous SiC core, a dense SiC coating of similar to 200 mu m thickness is deposited by Chemical Vapor Deposition (CVD); the coated material was tested against hot PbLi in corrosion experiments. The properties of the material in terms of thermal and electrical conductivities, flexural strength and elastic modulus were measured, with promising results for high-temperature FCIs.