High fracture toughness of 3Y-TZP ceramic over a wide sintering range
The structural degradation resulting from the phase transformation of excrescent monoclinic form limits the long-term durability and sintering adaptability of the ZrO 2 -based ceramic components. The objective of the present study was to report on the use of the fully tetragonal nanocrystalline 3mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) powders as the starting material for ZrO 2 -toughened ceramics. The influences of time-temperature sintering conditions on the fracture toughness of the 3Y-TZP ceramics were investigated. Dense 3Y-TZP ceramics (>96% of theoretical density) with no monoclinic structure can be achieved with a Hollomon-Jaffe parameter (HJP) in the range of 46 K–52 K. The fracture toughness values of the 3Y-TZP ceramics were determined to be in the range of 4.0–6.2 MP m 1/2 , and these values did not vary significantly over a wide sintering range. Phase composition and microstructure analysis results indicate that the high fracture toughness over a wider range of sintering conditions can be attributed to the cooperativity between the transformation toughening mechanism and the critical grain size effect of the transition from the tetragonal to monoclinic phase of the 3Y-TZP.
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