title: The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics.
abstract: The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics was investigated. In order to differentiate between the distinct contributions of two dopants to the overall resistance to low-temperature degradation (LTD), specimens were prepared by infiltration of silica sol into pre-sintered 3Y-TZP pellets, produced from commercially available powders, which were alumina-free or contained 0.05 and 0.25 wt.%. After sintering, specimens were exposed to accelerated ageing in distilled water at 134°C for 6-48 h. X-ray diffraction was applied to quantify the tetragonal-to-monoclinic (t-m) phase transformation associated with the LTD, while a focused ion beam-scanning electron microscopy technique was employed to study the microstructural features in the transformed layer. The results showed that the minor alumina and/or silica additions did not drastically change the densities, grain sizes or mechanical properties of 3Y-TZP, but they did significantly reduce LTD. The addition of either alumina or silica has the potential to influence both the nucleation and the propagation of moisture-induced transformation, but in different ways and to different extents. The co-doped ceramics exhibited predominantly transgranular fracture, reflecting strong grain boundaries (limiting microcracking of the transformed layer), for alumina doping, and rounded grains with a glassy phase at multiple grain junctions (reducing internal stresses) for silica-doped material. These two additives evidently have different dominant mechanisms associated with the deceleration of LTD of 3Y-TZP, but their combination increases resistance to ageing, importantly, without reducing the fracture toughness of this popular biomaterial.
authors.affiliation: Engineering Ceramics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. Electronic address: samodurova.a@gmail.com.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Samodurova
authors.affiliation: Engineering Ceramics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Andraž
authors.initials: A
authors.lastname: Kocjan
authors.affiliation: Biomaterials Laboratory, Faculty of Dentistry, University of Sydney, Sydney Dental Hospital, 2 Chalmers St., Surry Hills, NSW 2010, Australia.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Swain
authors.affiliation: Engineering Ceramics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Tomaž
authors.initials: T
authors.lastname: Kosmač
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D006244:Hardness; D008422:Materials Testing; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D012822:Silicon Dioxide; D015040:Zirconium; D000537:Aluminum Oxide
keywords: Bioceramics; FIB-SEM; Low-temperature degradation; Microcracking; Zirconia