Improved thermoelectric properties of SiC composites with optimized TiB₂ network structures

Due to the scarcity of renewable energy sources and the increase in fossil fuel consumption, the development of materials for renewable and sustainable energy production has become an eminent concern, including thermoelectric power generation. Advanced ceramics such as SiC is a desirable alternative material for high-temperature thermoelectric applications. Although SiC has a high Seebeck coefficient, it has relatively low electrical and high thermal conductivities, which are undesirable properties for thermoelectric applications. Introducing transitional metal borides as a secondary phase to enhance the electrical conductivity of SiC is a common method. In this study, SiC granules were coated with TiB2 powders using a simple dry coating method and subsequently subjected to spark plasma sintering to produce composites with conductive network structures. To modify the morphology of the TiB2 network, SiC granules were classified with particle size ranges of 25-50 mu m to 75-100 mu m prior to the coating process, Increases of approximate to 130-500% in electrical conductivity was achieved depending on the matrix granule size distribution, which decreased with increasing SiC granule sizes, showed that the higher concentration of TiB2 network lowered the percolation threshold causing drastic increases in electrical conductivity. The ZT value increased by approximate to 50% in the 25-50 mu m range.