The corrosion behavior of aluminized Type 310S stainless steel (SS) in the wet seal of molten carbonate fuel cells was investigated. Coupons of Type 310S SS were aluminized by two different aluminizing methods: thermal spray and slurry-coating. In both types of samples Fe and Cr diffused readily into the Al layer at 650 °C. At first this interdiffusion is limited to the interfacial area. With time, Fe and Cr aluminides precipitate in the Al layer. The slurry-coated layer contains a higher concentration of FeAl and Fe3Al than does the thermal spray layer. Consequently, the slurry-coated layer also displays a greater degree of corrosion than the thermal spray layer.

The synthesis of polycarbodiimide and polyimide in a cyanate resin precursor was achieved. A unique procedure for achieving a high molecular weight of the molecular composite reinforcement molecules was demonstrated. In spite of phase separation being present during the processing, the final cured composites were transparent. The enhanced mechanical properties and the presence of a single Tg, which increases with rigid rod content, were indications that a molecular composite was achieved. The agreement between measured mechanical properties and those predicted using molecular mechanics simulations CERIUS2 software was encouraging.

The surface composition of BaTiO3, SrTiO3, and CaTiO3 perovskite (100) surface is determined by shell-model calculations. The TiO2-terminated surface is energetically favorable for BaTiO3 and SrTiO3, which is consistent with experimental observations on SrTiO3. On the other hand, the CaO-terminated surface is preferred for CaTiO3 where Ca2+ is the smallest 2+ cation in these titanates. Ions on (100) surface rumple and induce surface dipoles. The surface ferroelectric polarization stabilizes the surface and changes its sign as the surface composition changes from TiO2 to CaO. This phenomenon is expected to affect the stability and properties of epitaxial films on perovskite substrates.

Microstructural development of SCS-6 SiC fibers induced by creep deformation at 1400 °C is presented. Grain growth occurs in all SiC regions of the fiber during creep. Portions of the SiC4 region transform from βSiC to αSiC growing at the expense of the βSiC. The SiC1 through SiC3 regions of the fiber consist of a distinct (C + βSiC) two-phase region. The grain growth of the βSiC grains in the two-phase region is not as extensive as in the SiC4 region, suggesting that the presence of excess carbon may inhibit the growth of βSiC.

Photoluminescence for PbMg1/3Nb2/3O3 (PMN)– PbIn1/2Nb1/2O3 (PIN) solid solutions in the temperature ranging from 35 to 295 K have been obtained for the first time. An abrupt photoluminescence enhancement of the system has been observed to occur at ∼210 K, which can be attributed to the growing and merging of dynamic polar microregions or to the phase transformation of the material at this temperature. The PIN content has been found to affect the photoluminescence of the PMN-PIN system significantly. The photoluminescence mechanism for PMN-PIN has been studied.

We investigated the interactions between screen printed and fired layers of Bi2O3 and ceramic substrates of alumina and beryllia. It was found that the reaction products are invariably crystalline in nature. Several transitions of Bi2O3 in its polymorphic phases were found to occur on BeO substrates, while newly formed compounds have been observed to grow on alumina substrates, i.e., Al4Bi2O9 on 99.9% Al2O3 and Bi12SiO20 on 96% Al2O3. Bismuth deeply penetrates in the ceramic interstices in all the cases. Until Bi2O3 is not completely reacted, this penetration is diffusion limited (penetration depth , where td is the reaction time) with values of the activation energy ranging from 3.7 ± 0.6 eV (BeO substrate) to 1.4 ± 0.06 eV (96% Al2O3 substrate). It is shown that these processes are notably different to those occurring in PbO/ceramic systems; moreover, they imply different adhesion phenomena of thick films on different substrates.

Amorphous to nanocrystalline ZrO2−3 wt. % Y2O3 powders were formed by chemical precipitation from mixed nitrate salt solutions. The powders were cold pressed and presintered in air for 2 to 6 h within the temperature range of 1100 °C and 1300 °C. Hot isostatic pressing was performed for 2 to 3 h within the temperature range of 1150 °C to 1350 °C in argon pressure of 150 MPa. Fully dense pellets with grain size of 22 nm to 45 nm were formed by application of low presintering temperatures.

Spray-dried granules were observed by a laser microscopy with the immersion liquid technique. The binder distribution in the granules was analyzed from light intensity profiles of the images. The results showed that a surface layer with a large amount of the binder is formed in the spray-dried granule, and the segregation is influenced by initial binder concentration and size of atomized droplet. A computer simulation for soluble binder segregation during spray drying was conducted by considering simultaneously the solvent evaporation, the relative migration between the liquid and the particles, the diffusion, and drying shrinkage. The simulation coincides with the experimental results. To make uniform granules, reducing the amount of binder, liquid content, size of atomized droplet, and drying rate is favorable.

The sequence of microstructural changes occurring at the wet paste-aggregate interface is documented at an age as early as 5 min using the environmental scanning electron microscope (ESEM). Unlike other microscopic techniques, the ESEM allows pastes of normal water: cement ratio to be observed at early ages without reducing the paste to a powder. Evolution of the paste-aggregate microstructure is followed up to an age of 24 h. The region adjacent to the aggregate surface contains a phase with a morphology referred to as a “sheaf of wheat” morphology. The same interfacial region in a 10-day-old specimen has a microstructure similar to the interfacial transition zone (ITZ) reported in the literature. Variations of the “sheaf of wheat” morphology due to original water-to-cement ratio, mixing energy, incorporation of silica fume, and drying are documented. As revealed by energy dispersive x-ray analysis (EDS), the microstructure contains significant amounts of calcium and silica. These results indicate that the observed morphology is likely to be a calcium silicate hydrate (C-S-H) product that is a precursor to type I C-S-H. A description of the evolution of the observed microstructural features is presented. The “sheaf of wheat” morphology appears to be a general precursor to morphologies commonly seen in mature pastes.

A pulse-echo ultrasonic technique consisting of focused normal-incident compressional waves was used for the detection and evaluation of surface and subsurface damage in micaceous glass-ceramic and silicon nitride samples. The damage was produced by indentation with a tungsten carbide ball. The nature of the damage was found to be material-dependent and was classified into two types: Hertzian cone cracks in the silicon nitride, and distributed subsurface microcracks in the glass-ceramic. While the cone cracks were visible on the surface as circular ring cracks, the distributed subsurface microcracks were not associated with any visible surface cracks. Both the cone cracks and the distributed subsurface microcracks were easily detected by the ultrasonic technique. In addition, the ultrasonic beam was focused to different depths below the surface of the glass-ceramic sample to probe the subsurface region containing the microfracture damage.

Phase equilibrium and electrochemical studies of the ternary system Bi–Sr–O indicate the presence of six ternary oxides (Bi2SrO4, Bi2Sr2O5, Bi2Sr3O6, Bi4Sr6O15, Bi14Sr24O52, and Bi2Sr6O11) and three solid solutions (δ, β, and γ). An isothermal section of the phase diagram is established at 1050 K by phase analysis of quenched samples. Three compounds, Bi4Sr6O15, Bi14Sr24O52, and Bi2Sr6O11, contain Bi5+ ions. The stability of these phases is a function of oxygen partial pressure. The chemical potentials of SrO in two-phase fields are determined as a function of temperature using solid-state cells based on single crystal SrF2 as the electrolyte. Measurement of the emf of cells based on SrF2 as a function of oxygen partial pressure in the gas at constant temperature gives information on oxygen content of the compounds present at the electrodes. The chemical potentials of Bi2O3 in two-phase fields of the pseudobinary Bi2O3–SrO are measured using cells incorporating (Y2O3)ZrO2 as the solid electrolyte. The standard free energies of formation of the ternary oxides are calculated independently using emfs of different cells. The independent assessments agree closely; the maximum difference in the value of of component binary oxides. The results are discussed in the light of the phase diagram and compared with calorimetric and chemical potential measurements reported in the literature. The combined use of emf data from cells incorporating fluoride and oxide electrolytes enhances the reliability of derived data.

The universal form of embedding function suggested by Banerjea and Smith together with a pair-potential of the Morse form are used to obtain embedded atom method (EAM) potentials for fcc metals: Cu, Ag, Au, Ni, Pd, and Pt. The potential parameters are determined by fitting to the Cauchy pressure (C12 − C44)/2, shear constant GV = (C11 − C12 + 3C44)/5, and C44, the cohesive energy and the vacancy formation energy. The obtained parameters are utilized to calculate the unrelaxed divacancy binding energy and the unrelaxed surface energies of three low-index planes. The calculated quantities are in reasonable agreement with the experimental values except perhaps the divacancy energy in a few cases. In a further application, lattice dynamics of these metals are discussed using the present EAM potentials. On comparison with experimental phonons, the agreement is good for Cu, Ag, and Ni, while in the other three metals, Au, Pd, and Pt, the agreement is not so good. The phonon spectra are in reasonable agreement with the earlier calculations. The frequency spectrum and the mean square displacement of an atom in Cu are in agreement with the experiment and other calculated results.

Stresses supported by thin films of Cu passivated by SiOx have been measured upon thermal cycling. Very high stresses have been found, approaching 1 GPa in the thinnest (40 nm) films. Strengthening beyond yield occurs upon both cooling and heating, indicative of strong strain hardening in the Cu. The hardening continues down to at least 77 K. The yielding behavior of the Cu films has been characterized by a kinematic constitutive law, with exceptional strain hardening and a conventional temperature-dependent yield strength. The physical basis for this behavior is ascribed to confined shear bands in the Cu that induce large back stress. Transmission electron microscopy reveals aligned dislocations, which seemingly dictate the inelastic deformations in the shear bands.

The thermal stability of TiSi2 films on Si has been studied using the atomic force microscope (AFM). Changes in the surface roughness, film morphology, and sheet resistance were monitored during a series of rapid thermal annealing treatments. A linear increase of the root-mean-square (rms) roughness with time was observed during the early stages of degradation, in agreement with a surface diffusion model of thermal grooving, followed by an apparent saturation roughness that was attributed to the effective rupture of the film.

High energy resolved x-ray emission spectroscopy with variable electron beam excitation is applied for study of solid-phase reactions in the Ir/(111)Si system as a function of annealing temperature. The formation of Ir silicides as a function of depth is studied by measurements of Si L2,3 x-ray emission valence spectra at different electron excitation energies (3–10 keV), and the results are compared with those of Rutherford backscattering.

This paper discusses computational simulations of the evolution of stresses and deformation in unpassivated and SiO2-passivated Al lines on Si substrates. The finite element model accounts for elastic-plastic deformation in the Al lines during etching, passivation, and subsequent thermal cycling, by recourse to a generalized plane strain formulation within the context of a unit cell with appropriately constrained boundary conditions. The effects of different controlled variations in thermal history, and in the width, height, spacing, and yield behavior of the Al lines are analyzed; all these factors are seen to have potentially strong effects on the evolution of stresses within the lines. The predictions of the computations presented in this work are amenable for direct comparisons with experiments of curvature evolution along and perpendicular to the lines upon patterning, passivation, and thermal loading. The predicted stresses in metal interconnects can be directly used for reliability modeling purposes.

This work attempts to determine an appropriate passivation structure in the real integrated circuit (IC) pattern to improve stress-related reliability problems after the plastic packaging. Several different types of amorphous passivation materials were first tested to learn how effectively they protect underlying Al interconnection lines during thermal displacement-induced fatigue at temperature ranges from −65 °C to 150 °C. It was also studied how effectively the occurrence of cracking in a passivation layer can be suppressed by the improvement of its topological feature or increase in its thickness. According to the experimental results, an increase in passivation thickness up to 21,000 Å (7000 Å for oxide and 14,000 Å for SiN, respectively) was found to be a highly effective way to suppress stress-induced passivation damage on the inside of the chip in plastic IC packages. However, at the edges of the chip, smoothing of the passivation layer by a sloping metal sidewall was more important for the improvement of thermal cycling performance than thickening of the passivation layer.

Results are presented on the influence of the size of diamond powders and the laser power on the main Raman line. These results show conclusively that there is a consistent and systematic, reversible, downshift with both decrease of powder size, and increase of power. The shift can be explained by local heating of about 500 °C in the extreme case. Its significance applies to interpretation of the alleged “downshifting” of the 1332 cm−1 line in all diamond research. In the future, the grain size, the thermal contact, and the beam power must be carefully monitored in reporting and interpreting any frequency shifts.

Molybdenum and niobium carbides (β−Mo2C, NbC), as well as mixed carbides of molybdenum and niobium, were synthesized by the temperature-programmed carburization method (TPC) using a 20 vol% CH4/H2 gas mixture. The starting materials were MoO3, B-Nb2O5, and physical mixtures of B-Nb2O5/MoO3 with Nb/(Nb + Mo) atomic ratios varying from 0.2 to 0.8, respectively. Results from catalytic and temperatureprogrammed oxidation (TPO) measurements indicate that during the carburization of the Nb2O5/MoO3 physical mixture with Nby(Nb + Mo) = 0.8 there is, besides β−Mo2C and NbC formation, the appearance of a carbidic phase not detectable by x-ray diffraction (XRD). This phase appears to be highly active and selective for the dibenzothiophene hydrodesulfurization (HDS) reaction.

Measurements of Faraday and Mössbauer effects have been performed at room temperature for alkali silicate glasses containing a large amount of Eu2+ ions to examine the relation between local structure and magnitude of Verdet constant. The Mössbauer spectra indicate that about 80% of europium ions are present as a divalent state. The effective transition wavelength and effective transition probability for the 4f7 → 4f65d transition of Eu2+, which causes the Faraday effect, are derived from the wavelength dependence of Verdet constant. Both effective transition wavelength and effective transition probability are large compared with borate glasses, leading to the large magnitude of Verdet constant of the alkali silicate glasses. The variation of effective transition wavelength with glass composition is connected with the change of 6s-electron density of Eu2+ evaluated from the Mössbauer spectroscopy.