Synthesis of dense SiC compacts by liquid Si infiltration and their dissolution characteristics in molten Si–Cr alloy

In the SiC solution growth method, a graphite crucible is generally used to hold the Si-based solution and serve as the C source. However, the excess C supply by crucible dissolution can easily generate SiC microcrystals in solution, resulting in the formation of macro-defects (SiC inclusions) in the grown crystals. To address this issue, liquid Si infiltration (LSI) was used to fabricate dense SiC compacts for the application as a source material in the SiC solution growth. Preforms for LSI process were prepared using SiC powder and various C sources (graphite, carbon black, and carbonized phenol resin), and fabrication of dense SiC compacts with SiC area fractions of ∼90 % was achieved. Apparent mass-transfer coefficients and J D factors were obtained from evaluating the dissolution behaviors of LSI-fabricated SiC compacts in a molten Si–Cr alloy under forced convection, and the dissolution characteristics were compared with graphite and sintered SiC. These results suggest that mass transfer at the boundary layer is the rate-limiting step of dissolution in this system. The J D factors of LSI–SiC were the smallest than those of graphite and sintered SiC, suggesting that LSI–SiC is a suitable source material for SiC solution growth.