Papers by Laurent Gremillard
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial| 4.0 International License
Acta Materialia, Feb 1, 2020
Zirconia based bio-ceramics such as ZTA (Zirconia-toughened alumina) composite are often used in ... more Zirconia based bio-ceramics such as ZTA (Zirconia-toughened alumina) composite are often used in orthopaedic and dental implants. The hydrothermal ageing behaviour of zirconia in humid environments is an important factor affecting the lifetime of these biomaterials. It is a tetragonal-to-monoclinic phase transformation that has been shown to be both temperatureand stress-dependant. Here, ZTA composites with zirconia inclusion particles of different sizes were prepared. The influence of zirconia inclusions on internal stresses and thus on ageing behaviour was studied by Raman micro-spectroscopy and X-ray diffraction. The results show that the ageing kinetics result from a balance between stiffer matrix and increased tensile stress in the zirconia inclusion as the local alumina fraction increase. As a result, the maximum monoclinic fraction formed after1200 h ageing at 134°C decreases with increasing alumina content, showing the predominance of the stabilization of tetragonal particles by a stiff matrix over their destabilization by tensile stress.
HAL (Le Centre pour la Communication Scientifique Directe), 2017
Acta Materialia, Jun 1, 2007
We report on the structural transformations of Bioglass ® during thermal treatments. Just after t... more We report on the structural transformations of Bioglass ® during thermal treatments. Just after the glassy transition, at 550 °C, a glassy phase separation occurs at 580 °C, with the appearance of one silicate-and one phosphate-rich phase. It is followed by the crystallization of the major phase Na 2 CaSi 2 O 6 , from 610 to 700 °C and of the secondary phase, silicorhenanite, at 800 °C. The latter evolves from the phosphate-rich glassy phase, which is still present after the first crystallization. In order to control the processing of glass-ceramic products from Bioglass ® , crystallization kinetics were studied via differential scanning calorimetry measurements in the range of 620-700 °C and temperature-timetransformation curves were established.
Journal of Biomedical Materials Research Part A, Mar 15, 2009
Graded bilayered glass-ceramic composite coatings on Ti6Al4V substrates were fabricated using an ... more Graded bilayered glass-ceramic composite coatings on Ti6Al4V substrates were fabricated using an enameling technique. The layers consisted of a mixture of glasses in the CaO-MgO-Na 2 O-K 2 O-P 2 O 5 system with different amounts of calcium phosphates (CPs). Optimum firing conditions have been determined for the fabrication of coatings having good adhesion to the metal, while avoiding deleterious reactions between the glass and the ceramic particles. The final coatings do not crack or delaminate. The use of high-silica layers (>60 wt % SiO 2) in contact with the alloy promotes long-term stability of the coating; glass-metal adhesion is achieved through the formation of a nanostructured Ti 5 Si 3 layer. A surface layer containing a mixture of a low-silica glass (~53 wt % SiO 2) and synthetic hydroxyapatite particles promotes the precipitation of new apatite during tests in vitro. The in vitro behavior of the coatings in simulated body fluid depends both on the composition of the glass matrix and the CP particles, and is strongly affected by the coating design and the firing conditions.
Journal of The European Ceramic Society, 2007
In this work, polycaprolactone-coated alumina scaffolds were produced and characterized to valida... more In this work, polycaprolactone-coated alumina scaffolds were produced and characterized to validate the concept of polymer-ceramic composites with increased fracture resistance. Alumina scaffolds were sintered using a foam replication technique. An open-porous structure was achieved with ∼70% porosity and 150 m mean pore size. The polymer coating was obtained by infiltrating the scaffold with either a polycaprolactone solution or a polycaprolactone nanodispersion. The latter was obtained by an emulsion-diffusion technique. Dynamical Young modulus measurements and four-point bending tests were conducted to evaluate the mechanical properties of the composites. It was found that their elastic behaviour is controlled on the first order by the ceramic scaffold, while the fracture energy mainly depends on the polymer phase. A 10-20 vol.% addition of polycaprolactone to alumina scaffolds led to a 7-to 13-fold increase of the apparent fracture energy. SEM observations showed that toughening is due to crack bridging by polymer fibrils.
HAL (Le Centre pour la Communication Scientifique Directe), Nov 23, 2017
Trans Tech Publications Ltd. eBooks, Nov 20, 2007
In this study, we report on the effect of Bioglass® structural transformations on its sintering b... more In this study, we report on the effect of Bioglass® structural transformations on its sintering behaviour. In a previous paper, we showed that while heating up to 1000°C, five successive transformations occur: glassy transition, phase separation, two crystallization processes and a second glassy transition. The sintering of the material exhibits two main shrinkage stages associated to the two glassy transitions at 550°C and 850°C. At 580°C, the glass-in-glass phase separation induces a decrease of the sintering rate immediately followed by the crystallisation of the major phase Na2CaSi2O6 between 600 and 700°C, from the surface to the bulk of the particles. A completed inhibition of sintering takes place followed by a minor shrinkage due to volume crystallization. A plateau is observed until the second glassy transition.
Les materiaux ceramiques sont utilises dans les protheses orthopediques depuis 1965. Depuis, l’al... more Les materiaux ceramiques sont utilises dans les protheses orthopediques depuis 1965. Depuis, l’alumine, puis la zircone et les composites alumine-zircone servent principalement en arthroplastie de la hanche pour la realisation des couples de frottement (tete-cupule). Cet article traite de ces differents materiaux, de leur historique, de leurs avantages et de leurs inconvenients avant de conclure sur les developpements qui aboutiront a de nouveaux materiaux et de nouvelles protheses.
HAL (Le Centre pour la Communication Scientifique Directe), 2016
HAL (Le Centre pour la Communication Scientifique Directe), 2006
Journal of Materials Science, Jul 1, 2005
Acta Materialia, Dec 1, 2000
The aim of this study was to show the effects of small silica additions on the microstructures an... more The aim of this study was to show the effects of small silica additions on the microstructures and mechanical properties of 3 mol% yttria-stabilised zirconia (3Y-TZP) ceramics. Experiments were conducted on different batches of 3Y-TZP (pure to 2.5 wt% silica-doped). Microstructures were characterised mainly by transmission electron microscopy (TEM), but also by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Silica was found at triple junctions, but neither at grain boundaries nor in the lattice. Undoped zirconia ceramics exhibited faceted grains and significant internal stresses, while doped zirconias showed a much more rounded microstructure and a lower level of internal stresses. Low-temperature degradation (LTD) and slow crack growth (SCG) measurements were conducted on the different batches. The addition of silica strongly increases LTD resistance without affecting the SCG behaviour. The microstructural origins of the different behaviours are discussed.
Acta Biomaterialia, Nov 1, 2010
Polymethyl methacrylate (PMMA) bone cement is a commonly used bone adhesive and filling material ... more Polymethyl methacrylate (PMMA) bone cement is a commonly used bone adhesive and filling material in percutaneous vertebroplasty and percutaneous kyphoplasty surgeries. However, PMMA bone cements have been reported to cause some severe complications, such as secondary fracture of adjacent vertebral bodies, and loosening or even dislodgement of the set PMMA bone cement, due to the over-high elastic modulus and poor osteointegration ability of the PMMA. In this study, mineralized collagen (MC) with biomimetic microstructure and good osteogenic activity was added to commercially available PMMA bone cement products, in order to improve both the mechanical properties and the cytocompatibility. As the compressive strength of the modified bone cements remained well, the compressive elastic modulus could be significantly down-regulated by
HAL (Le Centre pour la Communication Scientifique Directe), Mar 5, 2018
HAL (Le Centre pour la Communication Scientifique Directe), 2010
Polymethyl methacrylate (PMMA) bone cement is a commonly used bone adhesive and filling material ... more Polymethyl methacrylate (PMMA) bone cement is a commonly used bone adhesive and filling material in percutaneous vertebroplasty and percutaneous kyphoplasty surgeries. However, PMMA bone cements have been reported to cause some severe complications, such as secondary fracture of adjacent vertebral bodies, and loosening or even dislodgement of the set PMMA bone cement, due to the over-high elastic modulus and poor osteointegration ability of the PMMA. In this study, mineralized collagen (MC) with biomimetic microstructure and good osteogenic activity was added to commercially available PMMA bone cement products, in order to improve both the mechanical properties and the cytocompatibility. As the compressive strength of the modified bone cements remained well, the compressive elastic modulus could be significantly down-regulated by
HAL (Le Centre pour la Communication Scientifique Directe), Dec 12, 2021
HAL (Le Centre pour la Communication Scientifique Directe), Dec 11, 2020
International audienc
HAL (Le Centre pour la Communication Scientifique Directe), Aug 24, 2021
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Papers by Laurent Gremillard