Fabrication of electrically conductive barium aluminum silicate/silicon nitride composites with enhanced strength and toughness

To acquire Si3N4-based composite with combination of high mechanical properties and excellent electrical conductivity, dense multi-walled carbon nanotubes (MWCNTs)-dispersed Si3N4 ceramics were fabricated, using BaCO3–Al2O3–SiO2 (BAS) as a second phase to improve the density and avoid reaction between MWCNTs and Si3N4. The results revealed that 40 wt% BAS prominently benefited the densification of MWCNTs-dispersed Si3N4 composites and promoted the phase transformation of α-Si3N4 to β-Si3N4, thereby contributing to superior mechanical properties. Additionally, the effects of MWCNTs on the densification, phase transformation, microstructure and properties were investigated. MWCNTs were well dispersed without damage in BAS/Si3N4 composites exhibiting excellent electrical conductivity. Consequently, these composites would be expanded to more applications including electrostatic chargeless bearing and electromagnetic interference shielding as well as high-temperature structural applications with geometrically complex morphologies.