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Here we report the microstructural dependence of nano-hardness ( H) and elastic modulus ( E) of microplasma sprayed (MIPS) 230 μm thick highly porous, heterogeneous hydroxyapatite (HAP) coating on SS316L. The nano-hardness and Young’s modulus data were measured on polished plan section (PS) of the coating by the nanoindentation technique with a Berkovich indenter. The characteristic values of nano-hardness and Young’s modulus were calculated through the application of Weibull statistics. Both nano-hardness and the Young’s modulus data showed an apparent indentation size effect. In addition, there was an increasing trend of Weibull moduli values for both the nano-hardness and the Young’s modulus data of the MIPS-HAP coating as the indentation load was enhanced from 10 to 1,000 mN. An attempt was made in the present work, to provide a qualitative model that can explain such behavior. [ABSTRACT FROM AUTHOR]

The soft chemical synthesis of self-assembled magnesium hydroxide (Mg(OH)) nanoplatelets with surface area as high as about 300 m g was achieved in the present work. The nanopowders such as MH, MH, MH were synthesized at ~30 °C without using any catalyst or surfactant using, respectively, precursor solutions of Mg(NO), MgCl, MgBr and characterized by XRD, BET surface area, BJH pore size analysis, FTIR, FE-SEM, TEM and EDX techniques. It was found that the MH and MH nanopowders comprised of nanoflowers formed by self-assembly of nanoplatelets and porous nanoplatelets, while the MH nanopowders comprised of a random assembly of nanocapsules. The powders possessed the technologically important quality of reproducible CO adsorption at room temperature and its desorption at a relatively lower temperature of 75 °C. Based on the experimental evidences, the mechanisms of various microstructure formations and CO adsorption mechanism were also proposed. [ABSTRACT FROM AUTHOR]

Symmetric shock experiments were conducted on a 10 μm grain size coarse alumina ceramic with a gas gun to identify its Hugoniot elastic limit (HEL). To understand the damage initiation and their subsequent growth mechanisms in coarse grain alumina subjected to shock impact at levels much above the HEL, additional asymmetric shock recovery experiments with the same gas gun were then deliberately conducted on the same alumina at shock pressure levels more than three times as high as the HEL and the fragments collected by a dedicated catcher system. Detailed characterization of the shock recovered alumina fragments by X-ray diffraction, nanoindentation, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy were utilized to understand the nature and process of failure initiation, incubational growth, coalescence and propagation leading to fragmentation. Based on these data a new qualitative damage model was developed to explain the deformation mechanism. [ABSTRACT FROM AUTHOR]