Preparation of Nanocrystalline Calcia‐Stabilized Tetragonal Zirconia by High‐Energy Milling of Baddeleyite

Abstract

For the first time, zirconia nanocrystalline powders were derived using baddeleyite as raw material by ultrafine milling. Powders containing 19 vol% of monoclinic phase were produced by milling of baddeleyite with addition of 11 mol% of CaO. Crystallite size of tetragonal and cubic phases in resulting powders is 3-5 nm and about 15 nm in the case of monoclinic phase. Typical agglomerate's size found by scanning electron microscopy ranges from~0.1 to 10 µm. Sintered ceramics with tetragonal zirconia content of 95 vol% and crystallite size of~50 nm are produced from the powders. *

Low‐temperature aging of baddeleyite‐based Ca‐TZP ceramics

“…The concentrations were chosen to characterize ceramics behavior in different “regions” of stabilizer contents: below optimal, optimal, over optimal. Optimal concentration of CaO corresponds to Ca‐TZP with the highest fracture toughness, reported in the previous work work …”

“…6.5Ca‐TZP ceramics, showing the best initial combination of hardness and fracture toughness, exhibit intermediate resistance to LTD in hydrothermal conditions: hardness remains in 10.0‐10.9 GPa range during the first 20 hours of aging, which follows by abrupt fall to ≈9 GPa. Fracture toughness drops during the first hours of hydrothermal aging from 13.3 MPa·m 0.5 to ≈8 MPa·m 0.5 , slowly decreasing to ≈7 MPa·m 0.5 after 30 hours aging.…”

“…However, little attention was paid to TZP ceramics prepared with use of alternative stabilizers, such as CaO. Fabrication of Ca‐TZP with fracture toughness of about 13 MPa·m 0.5 and hardness of 11 GPa, comparable with that of Y‐TZP, by high‐energy milling of baddeleyite was recently reported . Furthermore, preparation of nanocrystalline Ca‐TZP ceramics with bending strength of 730 MPa was recently reported by Labuz et al., however, no rigorous studies of aging of these ceramics were published.…”

An Engineering Zirconia Ceramic Made of Baddeleyite

“…Baddeleyite is much cheaper than zirconia synthesized from zircon, but chemical ways of stabilizing are not efficient for baddeleyite. In [ 4 ], high-energy milling was successfully applied to baddeleyite to prepare CaO-stabilized ZrO 2 nanopowder. CaO was chosen as an inexpensive alternative to Y 2 O 3 and CeO 2 which commonly used for producing engineering TZP ceramics.…”

Низкотемпературная Деградация Композитной ATZ-керамики, Армированной Многостенными Углеродными Нанотрубками

“…циркония) [7]. Стабилизации тетрагональной фазы обычно добиваются использованием разнообразных стабилизаторов: от классических Y 2 O 3 [8], CeO 2 [9] до более редко используемого, но самого дешевого CaO [10][11][12][13].…”