Effect of Y₂O₃ Additions on Microstructure and Properties of Alumina–Magnesia Ceramics

The purposes of this research are to prepare and investigate the characterization of 0.7MgO-xY₂O₃-(99.3-x)Al₂O₃ by varies x at 0.0, 2.0, 4.0, 6.0, 8.0 and 10.0 wt% (AMY). AMY samples were synthesized by solid state reaction under two different sintering methods conventional sintering method (NS) and two stage sintering method (TS). Ceramic samples were sintered by conventional sintering at 1600°C for 5 h and using two stage sintering with the first sintering temperature (T₁) at 1600°C for 30 min and cooling down to the second sintering temperature (T₂) at 1450°C for 10 h. The phase composition of the samples were characterized using XRD technique. XRD patterns from two method sintering revealed phase combination of Al₂O₃, MgAl₂O₄, MgO and Y₂O₃. It was found that it is not different XRD patterns from two method sintering. SEM micrographs form NM and TS showed that the shape of the ceramic grains were polyhedron and ellipsoid, while the grain sizes form NS were in the range of 0.91-1.00 μm and the grain sizes from TS were in the range of 0.34-0.48 μm. The samples from NS and TS is showed optimum mechanical properties by AMY with Y₂O₃ additions between 4-6 wt%.