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Objective: The corrosion behavior of titanium alloy (NiTi) orthodontic wires shows a high resistance to corrosion in various solutions, such as Ringer's solution, artificial saliva, sodium chloride solution, and others. In these different liquids, NiTi corrosion resistance is higher than that of stainless steel or cobalt-based alloys. These research studies the behavior of the nickel-titanium Orthodontics archwires in the mouth by three methods. Methods: The first testing was the SEM that can perform EPMA (Electro Probing Micro Analysis), microanalysis X, and local and quantitative elementary analysis, and the examination of NiTi are observed in two ways: cross sectional and surface examination. The second one was the electrochemical analysis performed by immersion in an artificial saliva solution consisting of lactic acid at 0.1 moles per liter and sodium chloride at 0.1 mole per liter: Two types of NiTi orthodontic arches were tested. The first ones are from the manufacturer Ortho Classic and were used in the mouth for 4-6 weeks. The second arches are from the manufacturer AZ Dent and were new. The last test was the TEM cartography that shows the atoms and their dispersion on the surface of the wire. Results: The results showed that the presence of corrosion cells in the artificial saliva proved that the NiTi orthodontic archwires were able to initiate the process of corrosion in the mouth, particularly at the point of friction in contact with the braces (Ti6Al4V). Conclusion: The results obtained by the MET on thin sections of orthodontic arches prepared by the FIB method revealed the presence of double or multiple layers of titanium oxide and N-oxide plus aluminum.

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.

In this study, phosphocalcic coatings on titanium alloy Ti6Al4V substrate are elaborated using Electrodeposition (ELD) by adding optimized amount of hydrogen peroxide H2O2 into the electrolyte. Structural analysis is performed by X Rays Diffraction and the data are treated using the RIETVELD method. The characterization of the coatings elaborated by ELD showed that the H2O2 amount variation has an influence on the morphology, the crystal size and the chemical composition (monophasic or biphasic) of the coatings.

This work aims to study by neutron diffraction the evolution of metastable phases of CuAlBe shape memory alloy after plastic deformation. Two samples were studied: the first one deformed by cold rolling at a reduction rate of 15% and the second, deformed by cold rolling at 15% followed by hot rolling at 200°C for a reduction rate of 30% respectively. Before plastic deformation, the material is fully austenitic at ambient temperature. Its crystallographic texture is mainly characterized by a partial fibber. After deformation, this partial fibber disappears and the crystallographic texture is composed by isolated orientations. At higher reduction rates, the texture of austenitic phase remaining in the material is characterized by a fibber. The rolling process modifies metastable phase quantities. After deformation at a reduction rate of 15%, the volume fraction of metastable austenite remaining is close to 8%. Plastic deformation also greatly modifies the characteristic transformation temperatures and enlarges the hysteresis. The material plastically deformed after hot rolling presents large variations of intensities of diffraction peaks belonging to martensite phase during a thermal cycle at low temperature. This effect is attributed to a reorganization of variants due to an evolution of crystallographic texture of martensite.

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.

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 residuals stresses and texture of the new bone crystals reconstituted at the interface using synchrotron radiation on ID15 at ESRF in Grenoble, France.

In this paper we present two studies in order to evaluate the residual stresses in two materials. The first one, the residual stresses regenerated in shot peened aluminium plate by neutron diffraction on the strain imaging instrument SALSA at the Institut Laue Langevin, Grenoble, France, also the validation of a model of finite element analysis permitting to predict the final deformation. The second example of this work we use the cobalt-alloys coating deposited on stainless steel forging tools via Plasma Transfer Arc (PTA) process, the evaluation of the residual stresses and characterization of phases close to substrate/coating interface were done by Synchrotron X-ray diffraction.

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.

Synchrotron X-ray diffraction is reliable to measure residual stresses and characterize existing phases close to substrate/coating interface. In the present study, we focus on the cobalt-alloys coating deposited on stainless steel forging tools via Plasma Transfer Arc (PTA) process. Forging tools always work in high temperature conditions. Since fatigue crack is often detected near to the interface, we used synchrotron radiation to characterize residual stress profiles both in the substrate and coating sides. Also, we defined phases inside diluted substrate layers and in the stellite coating using a Rietveld refinement.

The use of the implants has become current since 1930. With the improvement of technology, titanium alloy coated with nano-hydroxyapatite has been used in the medical field. As a long-term establishment is a meter of the therapeutic success, it is necessary to use biocompatible implants in order to have good mechanical and fracture resistance at the interface bone-implant. 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 implantation must have the same mechanicals properties as the natural bone in order to accept the implant. Therefore we studied the residuals stresses of the new bone crystals reconstituted at the interface applying non destructive x-ray diffraction and using finite element analysis in order to compare the results.

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.

The quantitative evaluation of the preferential orientation of crystallites by the synchrotron and neutron diffraction techniques during regeneration at the interface with implant gives a good prediction of the mechanical properties of the bone. During the process of bone healing after implantation, the speed and quality of regeneration is affected by the nature of the implant surface. Titanium alloy (Ti-Al-4V) is currently coating with the hydroxyapatite (HAp), Ca10(PO4)6 (OH)2, in order to obtain a stable and functional direct connection between bone and implant. At the interface implant-bone, the new bone reconstituted after implantation must have the same mechanical properties of bone in order to accept the implant. Therefore, it is necessary to study by means of two non destructive techniques: neutron diffraction and synchrotron radiation, the crystal growth and texture of this new bone crystals reconstituted at the interface.

In recent years, nanostructured coatings by Plasma Thermal Spraying (PTS) attracted intense interest due to their enhanced mechanical properties as hardness, strength and ductility. The aim of this study was to evaluate the influence of coating the implant by nanohydroxyaptite, n-HAp, Ca10 (PO4)6(OH)2. The results obtained with n-HAp will also compared with the implant coated with HAp. Bone is a composite material in which are associated a mineral phase in the form of crystals of HAp and an organic matrix constituted by collagen. The c-axes of HAp and the collagen fibers are preferentially oriented in the direction of the stresses that the bones need to withstand. At the interface implant-bone, the new bone reconstituted after implantation must have the same proprieties of the original bone in order to have good fixation with the implant. Therefore, it is necessary to study the mechanical properties of this new bone crystals reconstituted at the interface with the implants coated with n-HAp and HAp by neutrons diffraction on D20 at ILL.

A full review for technological processes used today, in dental prostheses industry for titanium casting, both in Europe and in United States, reveal that, there is no equipment available on the market able to cast small titanium parts in secondary inert vacuum by induction melting and centrifugal casting. All these advanced processes together contribute to an original concept of the Denticast System. The computer controlled cast sequence is another important factor contributing to a robust system, able to reproduce the achieved technological quality in a reliable manner. Mechanical testing (tensile and hardness) shows that the different alloys used in Denticast project and cast using the prototype, are in most of the results superior to those obtained with two different commercial systems (pressure-vacuum and centrifugal systems). The samples are usable for dental prosthesis without any risk for the patient health.

The aim of this study was to create a nano-structured coating using Plasma Thermal Spraying (PTS). This process consists in introducing pre-agglomerated nanosized particles in a high-temperature and high-velocity gas jet and projected them onto the substrate to form, layer by layer, a nanostructured coating. In order to retain nanometer grain sizes in the deposited coating through specific PTS technologies, a thermal field and velocity distribution in the plasma jet are analytically calculated. A finite element analysis is employed to calculate the thermal field evolution inside the agglomerated particles and the thermal induced internal stress distribution is determined. The parameters determined by the theoretical analysis are used for experimental coatings. The average crystallite size of nano-hydroxyapatite powder was 90nm. After deposit via Plasma Thermal Spraying (PTS) process and followed by a 2 hours heat treatment to reduce amorphous fraction, the experimental deposited coating shows that it retains the nanometer crystallite sizes. The substructure of nanocrystals was evaluated at about 120nm in size. Such a nanocoating may play the role of nucleation site to bone, allowing a faster stabilization of the implant.

The basic principles behind human tissue response to artificial surface implantation may be developed under its biological aspect, it is necessary for a medical use to study the mechanical limits of every biomaterials to predict the tissue and the body's response according to the composition, the structure and the design of a biomedical material. To promote a stable and functional direct connection between bone and implant, titanium implants can be coated with materials based on calcium phosphate ceramics such as hydroxyapatite (HAp)(Ca10(P04)6(OH)2). The preferred orientation of HAp crystallites at the interface bone-implant in sheep tibia bones has been measured with the neutron 2-axis diffractometer D20 at the Institut Max von Laue-Paul Langevin (ILL), extracted 60 days after implantation. The implant has two faces, one coated and one non-coated with plasma-sprayed HAp (80 .m). We probed the samples with a spatial resolution of 0.5 mm started from the interface in order to inspect the reorganisation of the HAp crystallite’s distribution after implantation.

Stored energy plays a crucial role in recrystallization process. One can distinguish two contributions to this energy. The first one is the elastic energy, connected with residual stresses, i.e., with grain-grain interaction. Another part of the stored energy is due to dislocation density, which is mainly localized inside grains. The latter one is considered as a main driving force of recrystallization. However, the stored energy connected with residual stresses can also have some influence on this process. Both types of energy can be determined experimentally and predicted by deformation models. Taking into account both types of the stored energy, some features of recrystallization textures can be explained.

We intend to obtain information about crystal growth and orientation close to the bone-implant interface using a non-destructive method. We will compare the results at the interface of cortical bone for hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 (HAp) coated and uncoated titanium alloy. At the interface with an implant, bone tends to change its properties, affecting the acceptance of the implant. The preferred orientation of HAp crystallites at the interface bone-implant has been measured with the neutron 2-axis diffractometer D20 at the Institut Max von Laue-Paul Langevin. The implant has two faces, one uncoated and one coated with plasma-sprayed HAp (80 μm). We probed the samples with a spatial resolution of 0.5 mm starting at the interface in order to inspect the distributions of the HAp'crystallite distribution after implantation.

Bone is a composite material of collagen and porous hydroxyapatite crystallites, aligned parallel to each other, with the c -axis parallel to the long axis of the fibre. Its texture and crystallinity has been investigated by means of neutron diffraction, using the high intensity 2-axis diffractometer D20 at ILL in particular. We show spatially resolved pole figures on a composite sample of two bone pieces of different preferred orientation. We have selected the (1 1 1) reflection, which is nearly not affected by texture to characterise the crystallinity index, and (0 0 2) to show the texture because the c -axes of hydroxyapatite crystallites is directed along the axis of the bone.

The aim of the present study was to study the interface implant-bone by synchrotron radiation and neutron diffraction, the implant has two faces the first one coated with hydroxyapatite and the second uncoated. In orthopaedic surgery, Titanium alloy (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 have good mechanical properties at the interface with the implant. Therefore, we studied the texture of the reconstituted bone crystals at the interface applying two non-destructive diffraction methods, as well as the influence of the coating on crystallinity index. The required high spatial resolution was achieved utilizing high-energy synchrotron radiation on ID15 at ESRF in Grenoble, France, and the second method was done by neutron diffraction, the high-intensity with two-axis diffractometer was used, equipped with variable resolution: D20, at Institut Max von LauePaul Langevin (ILL) in Grenoble, France. In orthopaedic surgery, it is necessary to use biocompatible implants in order to have good mechanical and fracture resistance. Bone is a composite material whose components are primarily collagen and HAp. The c-axes of the apatite crystallites and the collagen fibres are preferentially oriented, e.g., in the long bones in the directions of the stresses that the bones need to withstand. HAp crystallizes in the hexagonal system and its unit cell parameters are a=9,4 A and c=6,8 A its space group is P63/m. Bone occurs in two principal structural forms: cortical, or compact bone, which forms a dense matrix, and spongy bone. We use cortical bone in this work. The long-term success of biomedical implants largely depends on the stable fixation of the implant to bones. Composite materials, in which metals have coated with ceramics, have been extensively reported as an alternative to plain materials in favour of a long-term fixation. The development of bioactive ceramic-alloy structures for implants has focused by the idea of combining the bioactivity of ceramics with the mechanical properties of selected metallic alloys. Ti-6Al-4V presents good mechanical proprieties and is biocompatible. HAp has low mechanical strength, but has a very good osteointegration and biocompatibility. The idea is to combine these two materials in order to have mechanical strength and good osteointegration proprieties at the interface. Plasma spraying is the most popular method for coating implant parts with HAp. In order to improve these coatings, it is necessary to investigate the texture and crystallinity evolutions of the bone’s crystal structure, as a function of the distance from the implant-interface.