Hydroxyapatite has become an important coating material for bioimplants, following the introduction of synthetic HAp in the 1950s. The HAp coatings require controlled surface roughness/porosity, adequate corrosion resistance and need to show favorable tribological behavior. The deposition rate must be sufficiently fast and the coating technique needs to be applied at different scales on substrates having a diverse structure, composition, size, and shape. A detailed overview of dry and wet coating methods is given. The benefits of electrodeposition include controlled thickness and morphology, ability to coat a wide range of component size/shape and ease of industrial processing. Pulsed current and potential techniques have provided denser and more uniform coatings on different metallic materials/implants. The mechanism of HAp electrodeposition is considered and the effect of operational variables on deposit properties is highlighted. The most recent progress in the field is critically reviewed. Developments in mineral substituted and included particle, composite HAp coatings, including those reinforced by metallic, ceramic and polymeric particles; carbon nanotubes, modified graphenes, chitosan, and heparin, are considered in detail. Technical challenges which deserve further research are identified and a forward look in the field of the electrodeposited HAp coatings is taken.
We examined the texture evolution in a superelastic Ni 50.7 Ti 49.3 (numbers indicate at.%) alloy under applied uniaxial stress using high-energy synchrotron X-ray diffraction in transmission geometry. Texture information is identified from the intensity variations along Debye-Scherrer rings recorded on area detector diffraction images. The 1 1 0 A austenite plane normals are aligned in the rolling direction and 2 0 0 A is in the transverse direction. Due to the B2-B19 lattice correspondence, the 1 1 0 A peak splits into four martensite peaks 0 2 0 M ,1 1 1 M , 0 0 2 M and 1 1 1 M . The stress-induced martensite is strongly textured from twin variant selection in the stress field with 0 2 0 M aligned in the loading direction while the maxima corresponding to1 1 1 M , 0 0 2 M and 1 1 1 M are at 60 • , 67 • and 75 • from the loading direction. (B19 unit cell setting: a = 2.87Å, b = 4.59Å, c = 4.1Å, ␥ = 96.2 • ). A comparison between the experimental and recalculated distribution densities for the polycrystalline NiTi shows a reasonable agreement. In addition, we compare our experimental results with a micromechanical model which is based on total energy minimization. In this case, we also observe an overall agreement.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.