Optical and mechanical properties characterizations of transparent polycrystalline MgAl2O4 spinel

The microstructure and mechanical properties of polycrystalline spinel ceramics (MgAl2O4) with high translucency were investigated. Several kinds of polycrystalline spinel ceramics were prepared under various sintering conditions, and single-crystal spinel and sapphire were used for comparison. The bending strength of polycrystalline spinel with smaller grain size fabricated without sintering aids exceeded that of single-crystal spinel. The bending strength at 1000 degrees C tended to be lower than that at room temperature. The fracture toughness of poly-crystalline spinel prepared without sintering aids measured by SEVNB was higher than that of spinel with sintering aids. By estimation of fracture strength considering different fracture origins, the polycrystalline spinel prepared without sintering aids might be fractured mainly from defects around residual spherical voids. If the size of voids can be minimized in poly-crystalline spinel fabricated without sintering aids, both high transmission and good mechanical properties could be achieved.

Automated summary

The microstructure and mechanical properties of high-translucency polycrystalline spinel ceramics (MgAl2O4) were studied. Different sintering conditions were used to prepare various polycrystalline spinel ceramics, which were compared with single-crystal spinel and sapphire. Polycrystalline spinel with smaller grain size, fabricated without sintering aids, exhibited higher bending strength than single-crystal spinel. The fracture toughness of polycrystalline spinel without sintering aids was also higher than that of spinel with sintering aids. By minimizing the size of voids, high transmission and good mechanical properties can be achieved in polycrystalline spinel without sintering aids.