Abstract

Si3N4 ceramics are one of the typical engineering ceramics with high strength, hardness, fracture toughness, corrosion resistance, and wear resistance and without carbon nanotubes (CNT), which have high thermal conductivity and electrical conductivity: they are an insulator. Due to the excellent sinterability of the Si3N4–Y2O3–Al203–TiO2–AlN system, the CNT-dispersed Si3N4 ceramics have higher strength, 722 MPa when produced by gas-pressure sintering and hot isostatic pressing, and 1,173 MPa when produced by hot pressing. The fracture toughness of CNT dispersed Si3N4 ceramics, fabricated by gas-pressure sintering followed by hot isostatic pressing and hot pressing is 6.6 and 6.5 MPa m1/2, and the hardness is 14.3 and 14.8 GPa, respectively. These electroconductive Si3N4 ceramics can be applied in various extremely severe mechanical and environmental conditions such as ceramic bearings for high-speed, high-temperature, high-corrosion, and high-vacuum environments, and can be also used as novel functional materials with high durability and electrical conductivity, which result from the achievement of densification at a lower temperature. These electroconductive Si3N4 ceramics can restrict degradation of system lifetime due to dust adhesion and because of this, they are expected to be applied as bearing materials for electronic components

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