Abstract: Cost-effective fabrication of high thermal conductivity Si3N4 ceramics was realized by using low-cost Si3N4 powder with relatively high oxygen content (1.85% (mass fraction)) as raw material and Y2O3-MgO as sintering additives. The effect of Y2O3 addition on the densification, microstructure, mechanical properties and thermal conductivity of Si3N4 ceramics was investigated. The results show that properly increasing the addition of Y2O3 not only promotes the densification and microstructure refinement of Si3N4 ceramics, but also contributes to the decrease of lattice oxygen content and the improvement of thermal conductivity. The sample containing 7% (mass fraction) Y2O3 sintered at 1 900 ℃ has the optimum comprehensive properties, and its relative density, flexural strength, fracture toughness and thermal conductivity are 99.5%, (726±46) MPa, (6.9±0.2) MPa·m1/2 and 95 W·m-1·K-1, respectively.
Key words: ceramics, Si3N4, Y2O3, thermal conductivity, microstructure, mechanical property, oxygen content
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