Microstructure and Properties of Thermal Electrode Material Si(3)N(4)–MoSi(2) Composite Ceramics

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, Si(3)N(4)–MoSi(2) 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-Si(3)N(4), MoSi(2), a small amount of Mo(5)Si(3), and an amorphous glassy phase. The MoSi(2) phase was evenly distributed in the matrix. The percolation network was formed with increasing MoSi(2) content. The strength of the composites reached its maximum value when the MoSi(2) content reached a critical point. The electrical conductivity behaved like a typical percolation phenomenon. The percolation threshold was about 30% to 45%.