Papers by Author: Alain Lodini

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Authors: Abdelilah Benmarouane, Helene Citterio-Bigot, Pierre Millet, Thomas Buslaps, Alain Lodini
Abstract: Technology developments of implant composition and manufacture have been used in the medical field. Several different implants have been developed with varying degrees of commercial success. As a long-term establishment is a measure of the therapeutic success, it is necessary to use biocompatible implants in order to have good mechanical and fracture resistance of new bone reconstructed at the interface with the implant. Titanium (Ti-Al-4V) implants coated with hydroxyapatite (HAp), Ca10 (PO4)6 (OH)2 are widely used in orthopedic applications in order to obtain a stable and functional direct connection between the bone and the implant. At the implant-bone interface the new bone reconstituted after implantation must have the same orientation as the natural bone in order to accept the implant. Therefore we studied the texture and the crystallinity of the new bone crystals reconstituted at the interface applying by high-energy synchrotron radiation on beamline ID15 at ESRF in Grenoble, France.
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Authors: Abdelilah Benmarouane, Hélène Citterio, Pierre Millet, Thomas Buslaps, Alain Lodini
Abstract: The aim of this work was to study the implant-bone interface by synchrotron radiation in order to show the evolution of the crystallites of hydroxyapatite (Hap) reconstituted at the interface with the implant. The implant used an orthopaedic surgery is the Titanium alloy (Ti-6Al-4V), the implants are currently coated with (HAp), Ca10 (PO4)6 (OH)2, in order to obtain a stable and functional direct connection between the bone and the implant. In this work, two implants have been used, the first one coated with HAp and the second uncoated. At the implant-bone interface, the new bone reconstituted after two months of implantation must have the same properties like the natural bone in order to accept the implant. Therefore we studied the crytallinity index and texture of the new bone crystals reconstituted at the interface using synchrotron radiation on ID15 at ESRF in Grenoble, France.
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Authors: Sebastian Wroński, Krzysztof Wierzbanowski, Andrzej Baczmanski, Chedly Braham, Alain Lodini
Abstract: Grazing incidence technique can be used to study samples with important stress gradients. The stress can be measured at very small depths, of the order of a few μm. The penetration depth of radiation is almost constant in a wide 2θ range for a given incidence angle α. It can be changed by an appropriate selection of α angle. This enables the investigation of stress variation with depth below the sample surface. There are, however, some factors which have to be corrected in this technique. The most important one is the X-ray wave refraction: it changes the wave length and direction of the beam inside a sample. These two effects cause some shift of a peak position and they have to be taken into account. For small incidence angles (α≤100) the corrections are significant and can modify the measured stress even of 70 MPa. The refraction correction decreases with increasing of the incidence angle. The corrections were tested on ferrite powder and on the ground AISI316L steel samples.
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Authors: Abdelilah Benmarouane, Pierre Millet, Thomas Buslaps, Alain Lodini, Veijo Honkimäki
Abstract: The aim of the present study was to study the interface implant-bone by synchrotron radiation, the implant has two faces the first one coated with hydroxyapatite and the second uncoated. In orthopaedic surgery, Titanium (Ti-Al-4V) implants are currently coated with hydroxyapatite (HAp), Ca10 (PO4)6 (OH)2, in order to obtain a stable and functional direct connection between the bone and the implant. At the implant-bone interface, the new bone reconstituted after two months of implantation must have the same properties like the natural bone in order to accept the implant. Therefore we studied the texture of the reconstituted bone crystals at the interface applying non destructive x-ray diffraction. The required high spatial resolution was achieved utilizing high-energy synchrotron radiation on ID15 at ESRF in Grenoble, France.
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Authors: Florin Serban, Andrzej Baczmanski, E. Labbe, Krzysztof Wierzbanowski, Alain Lodini
Abstract: Recently, austempered ductile iron (ADI) has emerged as a new class of ferrous materials and represents a major achievement in cast iron technology [1]. The mechanical strength and impact toughness of nodular iron are provided by the precipitation of the graphite phase as spheroids surrounded by ferrite (bull’s-eye structure) in a continuous pearlite matrix. The quality of ductile iron increases with the number of the graphite spheroids. A high spheroids volume fraction, which is mainly controlled by the inoculation process, limits the chemical segregation during solidification and ensures the structural homogeneity of the component. In this work, a lower value of Young modulus was obtained when the graphite phase was taken into account in the self-consistent modelling. For 12% of graphite the theoretical Young modulus agrees with the measured one (mechanical tensile test). The volume fraction of graphite was confirmed independently by micrographic observation (14%). It can be concluded that the macroscopic behaviour of ADI steel can be modelled by the self-consistent approach in which the austeno-ferritic aggregate is represented by an effective matrix, while instead of the graphite spherical empty spaces are introduced. Using such an approach it was shown that in the elasto-plastic range of deformation, presence of graphite phase caused stress relaxation.
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Authors: Abdelilah Benmarouane, Helene Citterio, Pierre Millet, Thomas Buslaps, Alain Lodini, Veijo Honkimäki
Abstract: The properties of the interface between biomaterials and the host tissue play an important role for the process of successful adaptation of implants. Extensive research has focused on shortening the time of osseointegration by modifying the surface in adding a coating such as hydroxyapatite (HAp). We have developed a new type of biocompatible nanohydroxyapatite (n-HAp) coatings, which are characterized before and after deposit on a Ti-6Al-4V substrate using neutron diffraction and scanning electron microscopy. Three months after the implantation in the sheep tibias, high-energy synchrotron radiation (ID15B, ESRF, Grenoble, France) diffraction studies of the cortical bone identify that the c-axes of HAp are preferentially oriented in the direction of the stresses that bone usually withstands. This non destructive analysis of the bone-implant interface proves that bone maturation is achieved successfully with this novel n-HAp coating and demonstrates that the mineralization is completed without spatial organization. None of these findings are obtained with uncoated titanium alloys. The presence of this n-HAp coating on Ti-6Al-4V substrate is decisive in obtaining this mature bone at the interface.
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Authors: Eric Labbe, Florin Serban, Mircea Nicoară, Alain Lodini
Abstract: The constant reduction of production costs and the development of materials during recent years are favoured the development of Austempered Ductile Iron (ADI) because of favourable combination of technological and structural properties. The process of forging on ADI makes it possible to obtain final parts with good dimensions. Moreover, Austempered Ductile Iron has a remarkable workability. ADI has many advantages, including the possibility of modifying and of improving the mechanical characteristics by thermo mechanical treatments while preserving a relatively low production cost, thus competing with many categories of steels. The study presented relates to the influence of the parameters of the thermo mechanical treatments on the proportion of residual austenite allowing modification of the mechanical characteristics of the material and on the evaluation of the residual stresses.
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Authors: Andrzej Baczmanski, Chedly Braham, Alain Lodini, Krzysztof Wierzbanowski
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Authors: Adele Carradò, Jean Michel Sprauel, Laurent Barrallier, Alain Lodini
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Authors: Andrzej Baczmanski, Chedly Braham, Alain Lodini
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