With good high temperature and corrosive resistance performance, ceramic based composites can be used as promising materials to replace metal thermocouple materials. In this study, Si₃N₄⁻MoSi₂ composites were prepared via hot pressing technology. X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM) were used to analyze the microstructure of the composites. The mechanical properties and electrical conductivity were tested. The results showed that the composites were composed of β-Si₃N₄, MoSi₂, a small amount of Mo₅Si₃, and an amorphous glassy phase. The MoSi₂ phase was evenly distributed in the matrix. The percolation network was formed with increasing MoSi₂ content. The strength of the composites reached its maximum value when the MoSi₂ content reached a critical point. The electrical conductivity behaved like a typical percolation phenomenon. The percolation threshold was about 30% to 45%.
Keywords: electrical conductivity; hot pressing; mechanical properties; microstructure; thermal electrode materials.