Pulsed Current Activated Sintering of Nanostructured ZrO₂ and 3YSZ and Their Mechanical Properties

As nanostructured materials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. When conventional sintering processes are used to sinter nano-sized zirconia powders, concomitant grain growth leads to the destruction of the nanostructure. This focuses attention on consolidation methods in which grain growth can be eliminated or significantly reduced. To accomplish this, rapid sintering methods have been widely used to sinter nano-sized powders. Nanopowders of ZrO₂ and 3YSZ were fabricated and rapidly consolidated using high-energy ball milling and the pulsed current activated sintering (PCAS). The sintering behavior and crystallite size ZrO₂ and 3YSZ powders were evaluated. A nanostructured dense 3YSZ compact with a relative density of up to 99% was readily obtained within one min. The hardness and fracture toughness of ZrO₂ and 3YSZ sintered from powders milled for 10 h were 450 and 1160 kg/mm², 3 and 4.4 MPa·m^1/2. Not only hardness but also fracture toughness of 3YSZ are higher than those of ZrO₂.