Magnesium aluminate spinel (MgAl₂O₄) composites were prepared by mixing the commercial Alumina and Magnesium Oxide as starting raw materials. Titanium oxide (TiO₂) and Zirconium oxide (ZrO₂) were used as additives. The mixtures were prepared as by milling of five different combinations using zirconia balls for 1 hour each. Then Cold Isostatic Press (CIP) at 200 MPa pressed the batches. The material properties, such as porosity and density, and thermal expansion of the composites were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and the dilatometer measurements. MgAl₂O₄ ceramic composites are composed of spinel and garnet structures. The thermal expansion coefficients (CTE) of MgAl₂O₄ composites with and without TiO₂ and ZrO₂ additives under different temperature condition (25 ^oC to 1,300 ^oC) were characterized for spinel thermal expansion study and it shows that the comparison between the five different sample combinations at 1,300 ^oC, adding TiO₂ or ZrO₂ by small percentage gives the lowest CTE (9.89E-06, 1.02E-05) respectively, but increasing ZrO₂ increases the CTE.

Keywords: Magnesium aluminate spinel, Thermal expansion, Titanium oxide, Zirconium oxide