Recycling Si scrap for SiC-Y₂O₃-Al₂O₃ ceramics via a single-step process

SiC has received significant attention owing to its exceptional properties including superior mechanical properties, high thermal conductivity, and a high melting point, which makes it ideally suited for the aerospace, nuclear, and semiconductor industries. Nevertheless, its strong covalent bonding requires prolonged processing times and high pressure to achieve near-full densification, leading to substantial energy consumption and increased production costs. Herein, we demonstrate the simultaneous synthesis and densification of SiC using Si particles derived from Si scrap through a single-step hot-press sintering. The specimen sintered at 1850 °C for 2 h under 30 MPa exhibited an average grain size of 1.86 ± 0.81 µm, relative density of 98.90 %, a Vickers hardness of 26.4 GPa, a reduced modulus of 355 GPa, and thermal conductivities ranging from 111.2 W/m·K at 25 °C to 47.6 W/m·K at 1000 °C. Furthermore, an experimental heat transfer model using the finite element method was employed to investigate the impact of microstructural characteristics on the thermal conductivity, showing good agreement between predicted and measured results. This novel recycling of Si scrap for the fabrication of dense SiC through a single-step hot-press sintering is a cost-effective and eco-friendly approach to significantly reduce the production costs of SiC-based ceramics with enhanced thermal conductivity and mechanical performance.