Ceramics-Silikáty 59 (2) 109-114 (2015)

IN-SITU FORMATION AND DENSIFICATION OF MgAl₂O₄–SmAlO₃ CERAMICS BY A SINGLE-STAGE REACTION SINTERING PROCESS

Stoichiometric magnesium aluminate spinel (MgAl₂O₄, MA)–samarium aluminate (SmAlO₃, SA) ceramics have been prepared at 1580°C for 4 h from calcined magnesia (MgO), commercial alumina (Al₂O₃) and samarium oxide (Sm₂O₃) by a single-stage in-situ reaction sintering (SIRS) method. The phase compositions, microstructures, shrinkage ratio, bulk density and cold compressive strength of the MA–SA ceramics have been investigated. The ceramics with 2.5 - 7.5 wt. % Sm₂O₃ are composed of MA and SA phases. The microstructures of the ceramics are dense. MA particles exist as angular shape, and their grain size varies between 2 and 10 μm but the average grain size is about 5 μm. SmAlO₃ particles form due to the reaction of Sm₂O₃ and Al₂O₃, and they distribute in the intergranular space of MA grains. The diameter shrinkage ratio, volume shrinkage ratio, bulk density and cold compressive strength of MA–SA ceramics are greatly improved due to the addition of Sm₂O₃.

Keywords: MgAl₂O₄–SmAlO₃, Sm₂O₃, Reaction sintering, Sintering properties, Strength