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Full-Text Articles in Engineering

Effect Of Sintering On Microstructure And Properties Of Hydroxyapatite Produced By Different Synthesizing Methods, N Monmaturapoj, C Yatongchai Dec 2010

Effect Of Sintering On Microstructure And Properties Of Hydroxyapatite Produced By Different Synthesizing Methods, N Monmaturapoj, C Yatongchai

Journal of Metals, Materials and Minerals

The aim of this study is to investigate the effect of the sintering schedule on microstructure and properties of hydroxyapatite which is produced by different synthesizing methods. Hence, wet-chemical precipitation and solid-state reaction were performed to prepare nano-sized hydroxyapatite (HA) powders. Powders were then uniaxially pressed and sintered by varying temperatures and times. XRD and SEM were used to identify phases and morphology. Density and porosity of the sintered sample were determined using the Archimedes technique. Flexural strength was measured by a universal testing machine. The results show that density and strength could be improved by increasing the sintering temperature …


Validation Of A Model For Static And Dynamic Recrystallization In Metals, Arthur Brown, Douglas Bammann Jan 2010

Validation Of A Model For Static And Dynamic Recrystallization In Metals, Arthur Brown, Douglas Bammann

US Department of Energy Publications

In this paper, modifications are proposed to a phenomenological plasticity model to account for the evolution of recrystallization and the resultant softening behavior. The novel model includes internal state variables representing dislocation density and the spacing between geometrically necessary subgrain boundaries. In order to capture both single and multiple peak recrystallization, the model tracks the evolution of recrystallized volume fractions for multiple cycles of recrystallization, and has a set of state variables for each volume fraction. A rule of mixtures is used to determine the average stress. The model is capable of capturing static recrystallization as well as both single …


Correlation Of Nanoindentation-Induced Deformation Microstructures In Diamondlike Carbon Coatings On Silicon Substrates With Simulation Studies, Ayesha J. Haq, Paul G. Munroe, Mark Hoffman, Phil J. Martin, Avi Bendavid Jan 2010

Correlation Of Nanoindentation-Induced Deformation Microstructures In Diamondlike Carbon Coatings On Silicon Substrates With Simulation Studies, Ayesha J. Haq, Paul G. Munroe, Mark Hoffman, Phil J. Martin, Avi Bendavid

Faculty of Engineering - Papers (Archive)

The effect of the presence of diamondlike carbon coatings deposited on (100) Si substrateson the deformation mechanisms operating in the silicon substrate during contact loadinghave been investigated by both cross-sectional transmission electron microscopy andmodeling of the stresses generated beneath the indenter tip. The observed subsurfacemicrostructures were correlated to the Tresca shear stress and the hydrostatic stressgenerated in the silicon substrate beneath the indenter tip. The presence of the coatingaltered the stresses generated in the substrate, and changed the deformation mechanismfrom one of principally phase transformation in uncoated Si to predominantly dislocationmotion in the silicon substrate for the diamondlike C¿Si system. …