title: Towards long lasting zirconia-based composites for dental implants: Transformation induced plasticity and its consequence on ceramic reliability.
abstract: Zirconia-based composites were developed through an innovative processing route able to tune compositional and microstructural features very precisely. Fully-dense ceria-stabilized zirconia ceramics (84vol% Ce-TZP) containing equiaxed alumina (8vol%Al2O3) and elongated strontium hexa-aluminate (8vol% SrAl12O19) second phases were obtained by conventional sintering. This work deals with the effect of the zirconia stabilization degree (CeO2in the range 10.0-11.5mol%) on the transformability and mechanical properties of Ce-TZP-Al2O3-SrAl12O19materials. Vickers hardness, biaxial flexural strength and Single-edge V-notched beam tests revealed a strong influence of ceria content on the mechanical properties. Composites with 11.0mol% CeO2or above exhibited the classical behaviour of brittle ceramics, with no apparent plasticity and very low strain to failure. On the contrary, composites with 10.5mol% CeO2or less showed large transformation-induced plasticity and almost no dispersion in strength data. Materials with 10.5mol% of ceria showed the highest values in terms of biaxial bending strength (up to 1.1GPa) and fracture toughness (>10MPa√m). In these ceramics, as zirconia transformation precedes failure, the Weibull modulus was exceptionally high and reached a value of 60, which is in the range typically reported for metals. The results achieved demonstrate the high potential of using these new strong, tough and stable zirconia-based composites in structural biomedical applications.
  
  
  
  Yttria-stabilized (Y-TZP) zirconia ceramics are increasingly used for developing metal-free restorations and dental implants. Despite their success related to their excellent mechanical resistance, Y-TZP can undergo Low Temperature Degradation which could be responsible for restoration damage or even worst the failure of the implant. Current research is focusing on strategies to improve the LTD resistance of Y-TZP or to develop alternative composites with better stability in vivo. In this work the mechanical characterization of a new type of very-stable zirconia-based composites is presented. These materials are composed of ceria-stabilized zirconia (84vol%Ce-TZP) containing two second phases (α-alumina and strontium hexa-aluminate) and exhibit exceptional strength, toughness and ductility, which may allow the processing of dental implants with a perfect reliability and longer lifetime.
authors.affiliation: Université de Lyon-INSA de Lyon, MATEIS CNRS UMR 5510, 20 Avenue Albert Einstein, F-69621 Villeurbanne Cedex, France.
authors.forename: Helen
authors.initials: H
authors.lastname: Reveron
authors.affiliation: Department of Applied Science and Technology, INSTM R.U. PoliTO, LINCE Lab., Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Fornabaio
authors.affiliation: Department of Applied Science and Technology, INSTM R.U. PoliTO, LINCE Lab., Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Palmero
authors.affiliation: DOCERAM, MOESCHTER GROUP Holding GmbH & Co. KG, Hesslingsweg 65 - 67, 44309 Dortmund, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Fürderer
authors.affiliation: Ceramic Materials, Swerea IVF AB, 431 53 Mölndal, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Adolfsson
authors.affiliation: Dept. of Engineering and Architecture, University of Trieste, Via Valerio 6a-34127-Trieste (TS), Italy.
authors.forename: Vanni
authors.initials: V
authors.lastname: Lughi
authors.affiliation: Dept. of Engineering and Architecture, University of Trieste, Via Valerio 6a-34127-Trieste (TS), Italy.
authors.forename: Alois
authors.initials: A
authors.lastname: Bonifacio
authors.affiliation: Dept. of Engineering and Architecture, University of Trieste, Via Valerio 6a-34127-Trieste (TS), Italy.
authors.forename: Valter
authors.initials: V
authors.lastname: Sergo
authors.affiliation: Department of Applied Science and Technology, INSTM R.U. PoliTO, LINCE Lab., Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Montanaro
authors.affiliation: Université de Lyon-INSA de Lyon, MATEIS CNRS UMR 5510, 20 Avenue Albert Einstein, F-69621 Villeurbanne Cedex, France; Institut Universitaire de France, 103 bd Saint-Michel, 75005 Paris, France. Electronic address: Jerome.chevalier@insa-lyon.fr.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Chevalier
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D002563:Cerium / Q000737:chemistry; D015921:Dental Implants; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; D002563:Cerium; C030583:ceric oxide; D015040:Zirconium; C028541:zirconium oxide
keywords: Alumina; Composite; Mechanical properties; Plasticity; Zirconia