Ageing of zirconia-toughened alumina ceramics under different hydrothermal conditions

Effect of dopants and sintering temperature on microstructure and low temperature degradation of dental Y-TZP-zirconia

“…Dopants are present in zirconia either as a distinct phase (Al 2 O 3 ) or as a solid solution like Y 2 O 3 and Fe 2 O 3 in small quantities. [46][47][48][49][50][51][52][53][54][55][56] They, however, influence the grain morphology, microstructure, mechanical properties and the stability of zirconia against LTD. 10,21,23,31,32,36,37,40,45,47,[56][57][58]78 Today the sintering of highly porous (∼50 vol.%) and then machined zirconia is widely used to obtain a dense ceramic with the mechanical and chemical properties required for dental restorations. The sintering conducted in solid state involves the diffusion of the ions across grain boundaries without the involvement of a liquid phase and its ability of large rearrangements of particles.…”

Property Degradation of Tetragonal Zirconia Induced by Low-Temperature Defect Reaction with Water Molecules

“…Tetragonal ZrO 2 has also good ionic conductivity; its conductivity is higher than that of cubic ZrO 2 at temperatures <700 °C . However, there exists a major drawback for tetragonal ZrO 2 ceramic: tetragonal ZrO 2 undergoes a spontaneous tetragonal to monoclinic transformation in the presence of water or water vapor when annealed at relatively low temperatures (63−400 °C), engendering cracks in the transformed surface due to the volume expansion accompanying the phase transformation, thereby severely degrading the electrical and mechanical properties. − …”

Analysis of stress field in Al2O3-ZrO2biomaterials by finite element method

“…The combination of various bioceramics with the development of partially stabilized zirconia and alumina is the part of biomaterials world becoming increasingly important in medical devises. The mechanical properties of Al 2 O 3 -ZrO 2 bioceramic materials are largely discussed [1][2][3][4]. Contrary to alumina ceramic, the zirconia is a very interesting potential candidate for orthopaedic devices due to its exceptional mechanical properties such as the tenacity and fracture [1].…”

“…Contrary to alumina ceramic, the zirconia is a very interesting potential candidate for orthopaedic devices due to its exceptional mechanical properties such as the tenacity and fracture [1]. As disvantage, they can be CONTACT S. Laasri laasrisaid@yahoo.fr affected by ageing phenomenon in humid environment degrading their mechanical properties related to structural phase change from unstable tetragonal to the monoclinic stable phase [2][3][4][5]. For this aim, the addition of Al 2 O 3 to ZrO 2 system is necessary to avoid the ageing process of zirconia [2][3][4].…”

“…As disvantage, they can be CONTACT S. Laasri laasrisaid@yahoo.fr affected by ageing phenomenon in humid environment degrading their mechanical properties related to structural phase change from unstable tetragonal to the monoclinic stable phase [2][3][4][5]. For this aim, the addition of Al 2 O 3 to ZrO 2 system is necessary to avoid the ageing process of zirconia [2][3][4]. Several mechanisms could jointly contribute to the improvement of the mechanical properties of these interesting composites such as reinforcement by microcracking, deviation or cracks decking [6].…”