Effects Of Y2o3 Addition On Densification And Thermal Conductivity Of Ain Ceramics During Spark Plasma Sintering

Spark plasma sintering (SPS) of AIN ceramics were carried out with Y2O3 as sintering additive at a sintering temperature 1,550 1,700 degrees C. The effect of Y2O3 addition on sintering behavior and thermal conductivity of AIN ceramics was studied. Y2O3 added AIN showed higher densification rate than pure AIN noticeably, but the formation of yttrium aluminates phases by the solid-state reaction of Y2O3 and Al2O3 existed on AIN surface could delay the densification during the sintering process. The thermal conductivity of AIN specimens was promoted by the addition of Y2O3 up to 3 wt% in spite of the formation of YAG secondary phase in AIN grain boundaries because Y2O3 addition could reduced the oxygen contents in AIN lattice which is primary factor of thermal conductivity. However, the thermal conductivity rather decreased over 3 wt% addition because an immoderate formation of YAG phases in grain boundary could decrease thermal conductivity by a phonon scattering surpassing the contribution of Y2O3 addition.