Silicon Carbide Composite Fabrication and Mechanical and Thermal Performance for Nuclear Reactor Applications

Chemical vapor infiltrated (CVI) silicon carbide fiber reinforced-silicon carbide matrix (SiC-SiC) composite is a relatively new material and has come under increased scrutiny as an attractive material for nuclear applications. In these materials, the interplay between fiber and matrix leads to enhanced fracture toughness. However, due to the inherent directionality of the fibers, under-standing the mechanical and thermal performance is complex and requires careful characterization. At General Atomics, a laboratory has been established to develop these materials for a range of applications, in particular for the Energy Multiplier Module (EM²), which is a gas-cooled fast reactor.

In this paper, the program of work that is being undertaken to fabricate and characterize SiC matrix com-posites is discussed. For mechanical testing, specialized fixtures have been developed to hold the thin ceramic composite specimens. For thermal testing, the purge gas species and flow rate have been identified as important parameters. Initial results on planar samples have been performed on SiC-SiC samples and hot pressed SiC samples.