Properties and pulsed current activated consolidation of nanostuctured MgSiO3-MgAl2O4 composites

Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Nanopowders of MgO, Al₂O₃ and SiO₂ were made by high energy ball milling. The simultaneous synthesis and consolidation of nanostuctured MgAl₂O₄-MgSiO₃ composites from milled 2MgO, Al₂O₃ and SiO₂ powders was investigated by the pulsed current activated sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Highly dense nanostructured MgAl₂O₄-MgSiO₃ composites were produced with a simultaneous application of 80 MPa pressure and a pulsed current of 2000A within 1min. The fracture toughness of MgAl₂O₄-Mg₂SiO₄ composites sintered from 60 mol%MgO-20 mol%Al₂O₃-20mol%SiO₂ powders milled for 4 h was 3.2MPa·m^1/2. The fracture toughness of MgAl₂O₄-MgSiO₃ composite is higher than that of monolithic MgAl₂O₄.