Synthesis of MgAl2O4 Spinel in a Thermal Plasma

In this paper, we report an experimental study concerned with the synthesis of MgAl₂O₄ spinel via plasma-assisted melting of powder components at an Al₂O₃/MgO weight ratio varied from 1 to 4. The presence of excess Al₂O₃ in the starting mixture has been shown to cause the characteristic Bragg peak 111 (~65°) of crystalline MgAl₂O₄ to shift to larger 2θ angles and broaden. According to scanning electron microscopy results, the surface microstructure of the synthesized materials is formed by densely packed octahedral stoichiometric MgAl₂O₄ crystals ranging in size from 10 to 500 μm. The materials have been found to contain local regions that allow the dynamics of crystal growth during melt solidification to be examined. The proposed spinel synthesis method can find application in the fabrication of small thermally stable parts by casting.