New insights into linear electrical properties of pressureless sintered SiC-MoSi2-AlN composites

Highly conductive SiC-MoSi 2 -AlN composites were fabricated by β-SiC, AlN and MoSi 2 powders with Y 2 O 3 additive via pressureless sintering. The effect of MoSi 2 content on the microstructure, mechanical and electrical properties of SiC-MoSi 2 -AlN composites was systematically investigated. A finer microstructure was obtained and electrical conductivity was enhanced with increasing MoSi 2 content. The impedance spectroscopy and potential-current measurements were implemented to figure out the electrical conduction mechanism. The introduction of MoSi 2 effectively reduced the Schottky barrier height at the grain boundary, and subsequently the U-I curves changed from nonlinear to linear electrical characteristics . The notable decrease in electrical resistivity was owing to the breakdown of grain boundaries and the formation of percolation paths. The percolation threshold was in the range of 0–5.44 vol% MoSi 2 , much lower than the reference value. The composites with 10 wt% MoSi 2 exhibited an electrical resistivity of about 60 Ω cm, suitable for infrared source element applications.