Rapid synthesis of high-purity 3C-SiC in Si-Nd-C solution at 1600 °C via poly-SiC seed lifting method

Abstract

High-purity SiC powders are the main source material for preparing the single-crystal SiC and advanced SiC ceramics. The current mainstream methods for synthesizing high-purity SiC have to choose solid-phase methods, which involve ultrahigh energy consumption and incomplete reactions due to the intrinsic properties of solid-state reactions. In this study, the rare earth metal, neodymium (Nd), served as a solubilizer of C in the Si-C solution to increase the solubility of C, thereby successfully synthesizing SiC polycrystals at 1600°C. Additionally, a poly-SiC seed lifting method was proposed to separate the synthesized SiC polycrystals from the Si-Nd-C solution to achieve the recycling of residual solution and the multiple uses of graphite crucible. Finally, a large poly-SiC ingot with a compactness of 71.93% was synthesized using a Si-30mol%Nd solvent, with a lifting speed of 2 mm/h at 1600°C for 7.5 hours. After the solvent inclusions in the poly-SiC ingot were removed through acid pickling, high-purity 3C-SiC powders (99.9978%) were prepared even though low-purity raw materials (99.32 to 99.94%) were employed. Compared with traditional solid-phase methods, the new liquid-phase method offers the advantages such as lower temperature, higher efficiency, lower energy consumption, and lower requirements for raw materials.

The authors' abstract, as published at the source. Journal of Materials Research and Technology, 2026 · DOI ↗