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 were prepared from calcined MgO, commercial Al2O3 and Sm2O3 by single-stage in-situ reaction sintering at 1580 C for 4 h. The phase compositions, microstructures, shrinkage ratio, bulk density and cold compressive strength of the MA-SA ceramics were investigated. The ceramics containing 2.5-7.5 wt% Sm2O3 were composed of MA and SA phases and their microstructures were dense. The MA particles had an angular shape and their grain size varied between 2 and 10 micron with an average size of about 5 micron. SmAlO3 particles, formed due to the reaction of Sm2O3 with Al2O3, were distributed in the intergranular spaces of the MA grains. The diameter shrinkage ratio, volume shrinkage ratio, bulk density and cold compressive strength of MA-SA ceramics were improved due to the addition of Sm2O3.