Optical and mechanical properties of compaction and slip cast processed transparent polycrystalline spinel ceramics

Transparent polycrystalline Magnesium Aluminate Spinel (MgAl2O4) specimens were formed by colloidal slip casting (SC) and uniaxial powder compaction (UDP) routes using powder with identical properties. SC and UDP formed specimens which were pressureless sintered and further subjected to hot isostatic pressing to eliminate the residual porosities and to achieve the transparency. SC samples exhibited better transmission compared to UDP samples. Mechanical properties were found to be lower by 10-15% for UDP samples and are complemented by the total fracture energy release rate (Jc) and JR-δ curves. Finally, the optical and mechanical properties were correlated with the processing routes.