Densification of Alumina and Silica in the Presence of a Liquid Phase

Alumina and silica powders were sintered at 1250° to 1460°C in the presence of liquid phases containing CaO, A1₂O₃, and SiO₂. The data were analyzed using the equation D = K log t +C and the Arrhenius equation. The activation energy for sintering decreases with increasing amounts of liquid phase.     

On the effects of oxygen cross-sections in the fast neutron fluence analysis for a reactor pressure vessel scraping test

Studies in support of the assessment of aging structural materials in pressurized water reactors are being performed at the Paul Scherrer Institut. To that aim, a state-of-the-art methodology based on applying a CASMO-4/SIMULATE-3/MCNPX calculation scheme has been developed. In the frame of the methodology validation, an investigation is currently reported pertaining to the sensitivity of the calculated results, for a specific reactor pressure vessel scraping test, to the nuclear data used with the Monte Carlo code. Thus, the MCNPX-2.4.0 calculations have been carried out using three different data libraries, based on JEF-2.2, ENDF/B-VI.8 and JENDL-3.3 evaluations, respectively.     

Analysis of indentation-derived effective elastic modulus of metal-ceramic multilayers

A numerical study was undertaken to study the elastic property of metal-ceramic multilayered composites derived from indentation testing. The model system features alternating thin films of aluminum (Al) and silicon carbide (SiC), free from any effect due to the underlying substrate. The anisotropic composite elastic response was obtained by simulating overall loading of the multilayer structure. Finite element modeling of instrumented indentation was then employed to calculate the indentation-derived modulus using the unloading portion of the load–displacement curve. The results from indenting the homogenized composite (with the built-in multilayer property) and from indenting the real multilayers (with Al and SiC layers explicitly accounted for) were compared. It was found that an indentation depth beyond approximately 8–10 initial layer thicknesses is sufficient to yield a valid composite elastic response. The effective modulus thus obtained is representative of the out-of-plane modulus of the multilayer composite.     

On the Nature of the Interface between Ag<Subscript>3</Subscript>Sn Intermetallics and Sn in Sn-3.5Ag Solder Alloys

We report on the nature of the orientation of Ag₃Sn and the Ag₃Sn/Sn interface in Sn-3.5Ag solder. Orientation imaging microscopy (OIM) and transmission electron microscopy (TEM) were used to characterize the orientation and nature of the interface, respectively. OIM and TEM showed that Sn-3.5Ag containing spherical Ag₃Sn particles does not have a preferred orientation with respect to the Sn matrix. However, needle-like Ag₃Sn formed during slower cooling appeared to have a preferred orientation within individual Sn colonies. The interface between Sn and Ag₃Sn appeared to be incoherent, as confirmed by high-resolution TEM analysis.     

Torsional oscillations of a plane lamina in a buoyant fluid

The correction to the torque on a torsionally oscillating plane in a viscous, thermally conducting fluid due to its density variations is calculated when the thickness of the shear laters us small in comparison to the dimensions of the plane. The mechanism that drives the system away from strictly isothermal conditions is viscous dissipation. The corresponding variations in the mean (axial and radial) flow and the mean temperature are investigated for relatively strong and weak buoyancy-momentum coupling. Method of matched asymptotic expansions is employed to study the resulting fluid motion which exists as a double-decker structure and depends upon three physical parameters.     

Integral measurements with a plutonium inert matrix fuel rod in a heterogeneous light water reactor lattice

As part of PSI's validatory efforts for neutronics calculations pertaining to inert matrix fuel (IMF) deployment in light water reactors, first-of-their-kind integral measurements have been carried out at the PROTEUS facility employing a specially fabricated Pu-Er-Zr IMF rod in a heterogeneous (boiling water reactor) test lattice. Analogous experiments have also been conducted with MOX and “dummy” IMF rods, providing the basis for a systematic comparison of experimental and calculational results.     

Reflection and transmission of electromagnetic waves normally incident on a plasma slab moving uniformly along a magnetostatic field

Power reflection and transmission coefficients are found for linearly and circularly polarized plane electromagnetic waves, normally incident on a plasma slab, moving uniformly along a magnetostatic field, normal to the slab boundaries. The solution is found by applying the boundary conditions in the rest frame, and then using relativistic transformations for the fields and the plasma parameters to find the reflection and transmission coefficients observed in the laboratory frame. The results for the circularly polarized incident waves are found in closed form. Numerical results are presented for linearly polarized incident waves. It is found that with an increase in the magnetostatic field, the absolute maximum of the reflection coefficient increases at different velocities. An increase in the magnetostatic field makes the slab more transparent at velocities for which the transmission coefficient with no magnetostatic field is very small. A dielectric-like behavior is observed for large magnetostatic fields. The sum of the power reflection and power transmission coefficients is found to be no longer equal to unity for velocity different from zero.