http://nathan.instras.com/ResearchProposalDB/doc-109.pdf

A review on polymer nanofibers by electrospinning and their applications in nanocomposites

https://cmapspublic3.ihmc.us/rid=1N3976C22-12M3P49-9V/Holladay%20et%20al.%20-%202009%20-%20An%20overview%20of%20hydrogen%20production%20technologies.pdf

An overview of hydrogen production technologies

Effective thermal conductivity of mixtures of e uids and nanometer-size particles is measured by a steady-state parallel-plate method. The tested e uids contain two types of nanoparticles, Al 2O3 and CuO, dispersed in water, vacuum pump e uid, engine oil, and ethylene glycol. Experimental results show that the thermal conductivities of nanoparticle ‐e uid mixtures are higher than those of the base e uids. Using theoretical models of effective thermal conductivity of a mixture, we have demonstrated that the predicted thermal conductivities of nanoparticle ‐e uid mixtures are much lower than our measured data, indicating the dee ciency in the existing models when used for nanoparticle ‐e uid mixtures. Possible mechanisms contributing to enhancement of the thermal conductivity of the mixtures are discussed. A more comprehensive theory is needed to fully explain the behavior of nanoparticle ‐e uid mixtures. Nomenclature cp = specie c heat k = thermal conductivity L = thickness Pe = Peclet number P q = input power to heater 1 r = radius of particle S = cross-sectional area T = temperature U = velocity of particles relative to that of base e uids ® = ratio of thermal conductivity of particle to that of base liquid ¯ = .® i 1/=.® i 2/ ° = shear rate of e ow Ω = density A = volume fraction of particles in e uids Subscripts

/pdf/thermal-conductivity-of-nanoparticle-fluid-mixture-54tj4jnmls.pdf

Thermal Conductivity of Nanoparticle -Fluid Mixture

Recent advances in friction-stir welding : Process, weldment structure and properties

Controlled self-organization of nanoparticles can lead to new materials. The colloidal crystallization of non-spherical nanocrystals is a reaction channel in many crystallization reactions. With additives, self-organization can be stopped at an intermediary step-a mesocrystal-in which the primary units can still be identified. Mesocrystals were observed for various systems as kinetically metastable species or as intermediates in a crystallization reaction leading to single crystals with typical defects and inclusions. The control forces and mechanism of mesocrystal formation are largely unknown, but several mesocrystal properties are known. Mesocrystals are exiting examples of nonclassical crystallization, which does not proceed through ion-by-ion attachment, but by a modular nanobuilding-block route. This path makes crystallization more independent of ion products or molecular solubility, it occurs without pH or osmotic pressure changes, and opens new strategies for crystal morphogenesis.

/pdf/mesocrystals-inorganic-superstructures-made-by-highly-4ywmg6vzs9.pdf

Mesocrystals: Inorganic superstructures made by highly parallel crystallization and controlled alignment

Materials Research Society Symposium - Proceedings

Reactive sputter deposition and properties of Ta x N thin films

The reaction kinetics of eutectic SnPb solder on Cu were studied and compared in the liquid state at 200 to 240 °C and in the solid state aged at 125–170 °C. The ternary phase diagrams of SnPbCu, the morphology of intermetallic compound (IMC), and the kinetics of growth of the intermetallics were used in the comparison. The temperature difference between these two reactions is only 30 °C, but the kinetics of reaction, as well as the morphology of IMC formation, are very different. The kinetics in the wetting reaction is four orders of magnitude faster than that in solid state aging. The Cu6Sn5 intermetallic morphology in solid state aging is a layer type, but it has a scallop-type morphology in the wetting reaction. The morphology strongly affects the kinetics. While the kinetic difference can be attributed to the difference in atomic diffusivity between the liquid state and the solid state, it is the morphology that determines the kinetic path in these reactions. We conclude that a fast rate of reaction,...

Wetting reaction versus solid state aging of eutectic SnPb on Cu

The reaction mechanisms in the Si/Ta/Cu metallization system and their relation to the microstructure of thin films are discussed on the basis of experimental results and the assessment of the ternary Si–Ta–Cu phase diagram at 700 °C. With the help of sheet resistance measurements, Rutherford backscattering spectroscopy, x-ray diffraction, a scanning electron microscope, and a transmission electron microscope, the Ta barrier layer was observed to fail at temperatures above 650 °C due to the formation of TaSi2, the diffusion of Cu through the silicide layer, and the resulting formation of Cu3Si precipitates. However, in order for the TaSi2 phase to form first, the Ta diffusion barrier layer must be thick enough (e.g., 50–100 nm) to prevent Cu diffusion into the Si substrate up to the temperature of TaSi2 formation (∼650 °C). Independent of the Ta layer thickness, Cu3Si was present as large nodules, whereas the TaSi2 existed as a uniform layer. The resulting reaction structure was found to be in local equilibrium on the basis of the assessed Si–Ta–Cu phase diagram at 700 °C, and therefore no further reactions were expected. The role of oxygen was also found to be important in the reactions and it seems to have a strong effect on the thermal stability of the barrier layer.

Failure mechanism of Ta diffusion barrier between Cu and Si

The interfacial reactions of near-eutectic Sn–Ag–Cu solder with Ni(P)∕Au metal finishes on printed wiring boards as well as in component under bump metallizations have been investigated in this work. With the help of the scanning electron microscopy and transmission electron microscopy it was discovered that the first phase to form was the metastable nanocrystalline ternary NiSnP layer that provided the substrate for the subsequent formation of (Cu,Ni)6Sn5. During cooling or in the subsequent reflows the metastable NiSnP layer partially transformed into the columnar Ni3P. In this transformation Sn atoms and impurities, which do not dissolve into the Ni3P, diffuse towards the remaining NiSnP layer. When the specimens are further annealed in solid state at 170°C the Ni3P phase transforms into Ni5P2 implying that some more Ni has diffused towards the solder. However, when Ni(P)∕Au finishes with a higher P content were used, only the ternary NiSnP layer was observed. Based on the mass balance and available th...

Jorma K. Kivilahti

Papers

Materials Research Society Symposium - Proceedings

Reactive sputter deposition and properties of Ta x N thin films

Wetting reaction versus solid state aging of eutectic SnPb on Cu

Failure mechanism of Ta diffusion barrier between Cu and Si

Phase formation between lead-free Sn–Ag–Cu solder and Ni(P)∕Au finishes