Zeolite P was formed from class F fly ash under hydrothermal conditions. The fly ash was reacted with 2.8 or 5 M NaOH at 100 °C. Zeolite of the above type was produced regardless of the NaOH concentration or the addition of quartz, thus indicating its formation over a wide range of conditions. The zeolite produced was of the NaP-type with a fibrous morphology. Analysis of the pore structure of this zeolite by the BET method indicates a type II isotherm. The specific surface areas of synthesized zeolites increased from 28.5 to 41.1 m2/g when the NaOH concentration was increased from 2.8 to 5.0 M. This zeolite showed a significant selectivity for the uptake of Cs and Sr. Cs uptake ranged from 7.67 to 8.61 meq/100 g while that of Sr ranged from 9.8 to 10.54 meq/100 g. The value obtained depended on the specific synthesis conditions. These values are higher than those observed for tobermorite prepared from the same fly ash even though the tobermorite exhibited a higher specific surface area.

Borosilicate glasses with different waste loadings were prepared by ambient melting, quenching, and annealing. Some melt compositions partially crystallize to durable phases of zircon and forsterite. The coexisting liquid quenches to glass and endures the leach tests. The waste loading dependent leach rate trends of these glasses are reminiscent of the mixed alkali effect. Raman spectra suggest initial increase in durability with increases in the depolymerization of silicate species. Fluorine and hydroxyl ions also contribute to depolymerization. Tetraborate and metaborate rings are identified in the Raman spectra. The durability is enhanced when tetraborate bands are more intense than the metaborate bands.

Mixtures of CaO–CdO (1 : 1) were hydrothermally treated in a pressure reactor at 200 °C and 200 psi of pressure during a period of 16 h. The evolution of the reaction was followed by x-ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetric (TG and DTG) analysis. Also, the composition of the filtered solutions was analyzed to determine the mechanism of the reaction as well as the thermodynamic solubility constant of the new compound formed. The results show that CaO and CdO react, giving rise to a new CaCd(OH)4 hydroxide whose thermodynamic solubility constant, 1.5 ± 0.4 × 10−11 M2, is six orders of magnitude lower than those of both Ca(OH) 2 and β–Cd(OH) 2. This low solubility constant justifies the Cd2+ concentration measured in the pore solution of cement matrices used to immobilize cadmium containing wastes. The mechanism of the reaction proposed is via dissolution of both Ca(OH) 2 and β–Cd(OH)2, Ca2+ and being the predominant species in solution.

Barium aluminum hollandite is a major phase in Synroc, a ceramic designed for the immobilization of high-level waste (HLW) from nuclear fuel reprocessing. Radioactive cesium substitutes into the channel sites, and such hollandites give 133Cs MAS nuclear magnetic resonance (NMR) spectra consisting of a single peak at 211 ppm in the absence of paramagnetic ions. However, the peak shifts to 640 ± 30 ppm and becomes extremely broad when Ti3+ replaces Al3+ in the channel walls of the hollandite structure, apparently because of Fermi contact interaction between the Cs nucleus and the unpaired electron of Ti3+. 133Cs MAS NMR of Synroc and hollandites is very sensitive to the presence of water-soluble CsAlTiO4 which would compromise the aqueous durability of Synroc. 133Cs MAS NMR spectra of Synroc-C, hot-pressed in metal bellows at temperatures as high as 1325 °C, do not indicate significant formation of CsAlTiO4. Synroc samples loaded with Cs and Sr only were shown by MAS NMR as well as electron microscopic techniques to be capable of incorporating nearly 10 wt.% Cs before CsAlTiO4 is formed.

Incinerator bottom ash samples have been characterized using analytical electron microscopy (AEM) techniques, including electron diffraction, energy dispersive spectroscopy, and electron energy loss spectroscopy. The samples were first separated by magnetic properties and density. Three resulting fractions were examined: the magnetic, high-density (MHD) fraction, the nonmagnetic/high-density (NMHD) fraction, and the nonmagnetic, low-density (NMLD) fraction. Examination of these samples revealed a variety of submicron microstructural features. For the MHD fraction, metal oxides, iron silicates, aluminum silicates, and calcium phosphate compounds were found in addition to amorphous material. The NMHD fraction contained elements similar to the MHD fraction but had more amorphous material; crystalline silicates were less common. Compounds such as MgO and chloroapatite were also found. The NMLD fraction contained SiO2 and numerous metal oxides. The results of some of these analyses were used to model leaching behavior of the ash. Based on the AEM results, three mineral phases were chosen as candidates for aqueous geochemical thermodynamic equilibrium modeling of pH-dependent leaching: chromite, chloroapatite, and zincite. In two of these three cases (chromite, chloroapatite), the selected mineral phase provided excellent agreement with the experimentally observed leaching behavior. AEM was shown to be a useful tool for elucidating mineralogy of complex environmental samples.

We have investigated the wetting angle, side band growth, and intermetallic compound formation of seven SnPb alloys on Cu ranging from pure Sn to pure Pb. The wetting angle has a minimum near the middle composition and increases toward pure Sn and pure Pb, but the side band growth has a maximum near the middle composition. The intermetallic compounds formed are Cu6Sn5 and Cu3Sn for the eutectic and high-Sn alloys, yet for the high-Pb alloys, only Cu3Sn can be detected. While no intermetallic compound forms between Cu and pure Pb, the latter nevertheless wets the former with an angle of 115°. The driving force of a wetting reaction, which may be affected by the free energy gain in compound formation, is discussed by assuming that rate of compound formation is fast.

A systematic study of material quality has been performed for intrinsic a–Si:H layers deposited by plasma enhanced chemical vapor deposition at excitation frequencies between 30 and 80 MHz (VHF). The process conditions were optimized not only for “device quality” opto-electronic properties but also for a uniformity in layer thickness better than 5% over the 10 cm × 10 cm substrate area. We found optimized homogeneities at different pressures depending on the excitation frequency. The effect of frequency at these optimum conditions on the material quality is small. VHF-intrinsic layers have been used in a–Si:H p+-i-n+ solar cells, in which both the p+ and n+ layer were made using 13.56 MHz. There is a clear correlation between material quality and solar cell parameters. Material deposited at low power densities is of so-called “device quality,” which is confirmed by demonstrating an initial efficiency of 10% for cells deposited at 65 MHz using a low power density. The deposition rate still is 2–3 times higher than the one at 13.56 MHz. Light-soaking of the cell leads to stabilization at 6% for the best cells, which compares well to conventional 13.56 MHz cells.

About 15 × 106 lbs of paint sludge, produced every year at Ford plants, is disposed of in landfills. An economical alternative to this disposal method, which reclaims or recycles components of paint sludge, is highly desirable to preserve valuable natural resources. Here, we describe an alternative to landfill disposal whereby paint sludge is converted into ceramic composites that can be used as reinforcing materials. The conversion of paint sludge to ceramic composite, I/N2/600, is achieved by pyrolysis under a nitrogen atmosphere. Two additional composites, labeled I/N2/1000 and I/NH3/1000, respectively, are prepared by sintering I/600 at 1000 °C under N2 and NH3. All three composites contain crystalline CaTiO3, BaTiO3, TiO2, amorphous alumina, and carbon. I/NH3/1000 contains an additional crystalline phase of titanium nitride. The application of these composites as reinforcing materials is demonstrated in the fabrication of representative metal matrix composites (MMC's) and reinforced plastic components.

Compliance with the increasingly stringent environmental laws will force the phasing out of conventional methods for the manufacture of all semiconductor devices. Development of processes with the highest possible material and energy efficiencies is the heart of the present ecological preservation efforts. Besides other benefits, rapid isothermal processing (RIP) also uses less energy than furnace processing. Further increase of material and energy efficiencies is possible by using rapid photothermal processing. Central to this method is the use of quantum photoeffects in conventional RIP systems. This approach can be consolidated with advanced chemical vapor deposition methods that further lower the wastages leading to systems that can give significant improvements over those presently used. Key experimental results and possible future directions are presented.

A substitute additive, HBF4, has been discovered that will replace Hg(NO3)2 catalyst for dissolving aluminum spent nuclear fuels in nitric acid for recovery of usable materials. The catalyst or substitute is necessary to penetrate a protective oxide film that continuously forms on the Al surface in the oxidizing acid. A penetration rate of alloy Al-6061 T6 of 40 mg/cm2-h can be achieved in a continuous dissolution process at 100 °C using a dissolvent of 0.15 M HBF4 in 7 M HNO3 that achieves a steady-state composition of 1.0 M Al3+ and 3.3 M HNO3, while maintaining a corrosion rate of a type 304L stainless steel dissolver vessel of 0.015 mm/mo. The penetration rate of aluminum is correlated with the equilibrium concentration of HF in the system. The postulated mechanism involves dissolution of the alumina film by approximately 0.006 M HF in equilibrium with the HBF4 and complexed aluminum fluoride species in nitric acid, which provide a large semi-buffered supply of HF. This allows the HNO3 to attack the aluminum metal. The small concentration of HF does not compete favorably with HNO3 for reaction with and consumption by Al.

The present authors have already reported that barium oxide is the most effective catalyst for the conversion of waste polystyrene into styrene including both monomer and dimer. Around 85 wt.% of waste polystyrene was converted into styrene when it was degraded at 623 K in the presence of barium oxide as catalyst. In this paper, the preparation and the thermal degradation of polystyrene films with dispersed catalyst are described for a design of recyclable plastics for better environment. More than 85 wt.% of the films was degraded into styrene at 623 K without addition of other catalytic compounds. Techniques for foaming the films using either nitrogen or carbon dioxide are discussed. It was found that the polystyrene foams with dispersed catalyst are well converted into styrene when they are simply degraded at 673 K.

Using a scanning laser microscope and mercury porosi-meter, we evaluate the effects of an excellent car-coating treatment on resistance to environmental corrosion after aging for three years. The treatment maintains the clear surface. The effect can be explained mainly by the contact angle of sessile drops.

The effect of the crystal structure of starting alumina powder and electric pulsing on the initial stages of densification has been studied in the temperature range of 1200– 1500 °C. Multiple electric pulsing cycles enhance the densification significantly. The α-alumina powders consolidate more readily in comparison to γ-alumina powders. A high density α-alumina specimen (>98% of theoretical density) was obtained at 1300 °C in less than 10 min.

The morphological stability of ultrahigh vacuum deposited Ag film on (001)Si has been drastically improved by the deposition of 1 to 5 nm thick interposing Au layers. In Ag/(001)Si samples, Ag islands were found to form after annealing at 200 °C for 1 h. In contrast, continuous and uniform metal layer persisted after annealing at 500 °C for 1 h in samples with a thin intermediate Au layer. The significantly improved morphological stability is attributed to the strong intermixing between Au and Ag atoms at the metal/Si interface. The intermixing lowers the interface energy between metal layer and (001)Si.

This paper reviews the past, present, and future of the hydroxyapatite (HAp)-based biomaterials from the point of view of preparation of hard tissue replacement implants. Properties of the hard tissues are also described. The mechanical reliability of the pure HAp ceramics is low, therefore it cannot be used as artificial teeth or bones. For these reasons, various HAp-based composites have been fabricated, but only the HAp-coated titanium alloys have found wide application. Among the others, the microstructurally controlled HAp ceramics such as fibers/whiskers-reinforced HAp, fibrous HAp-reinforced polymers, or biomimetically fabricated HAp/collagen composites seem to be the most suitable ceramic materials for the future hard tissue replacement implants.

This paper presents tie-lines between Pr1+xBa2−xCu3O7−δ and liquid on a PrOy –BaO–CuO ternary phase diagram at 965, 970, 975, 980, and 990 °C in air atmosphere, for which knowledge is necessary to fabricate composition controlled Pr1+xBa2−xCu3O7−δ single crystals by the solution growth method. Liquidus faces have been investigated by dipping MgO single crystal rods into the thermal equilibrium melt at various temperatures and analyzing the composition of the adhering melt by ICP. The compositions of Pr1+xBa2−xCu3O7−δ solid solution coexisting with various compositions of liquids were obtained by quantitative EPMA analysis of quenched melts. Tie-lines were calculated by applying the lever rule to these experimental data for solid compositions and liquidus faces. Furthermore, the relationships between solid solubilities and peritectic temperatures of Pr1+xBa2−xCu3O7−δ are reported.

A new method was developed to obtain high density, uniform diamond nuclei via bias-assisted hot filament chemical vapor deposition. A negative bias was applied between a mesh (installed above the filament) and the substrate to produce abundant uniform ions at the growth surface. Raman spectroscopy, scanning electron microscopy, and Auger electron microscopy were used to analyze the films obtained. The results show that a layer of diamond film with a nucleation density of 109/cm2 can be obtained after 10 min deposition under 1 Torr.

Thin single crystal films of N-(4-nitrophenyl)-(L)-prolinol (NPP) were prepared using the modified shear method. The surface orientation of the single crystal films was determined by x-ray diffraction and was found to be [101]. Polarized microscopy showed uniform birefringence and complete extinction when the thin film was rotated under crossed polarization, implying single crystal thin films with uniform surface were obtained. The molecular orientation in the NPP thin film was studied by polarized UV-visible and polarized micro-FTIR spectroscopy along with x-ray diffraction. The orientation of the NPP molecules was found to be almost parallel to the plane of the film. This parallel orientation is because of the polar (hydrogen bonding) interaction of the −(OH) and the N=O groups of the NPP molecule with the hydrophilic substrate surface. The results of the second harmonic generation (SHG) measurements are consistent with such a molecular orientation. These results show that the final molecular and crystallographic orientation in the film is determined by its initial molecule-substrate interaction.

A theoretical model of the combustion synthesis process has been developed to study the ignition of a self-propagating combustion synthesis process in the Nb–C system. Compared with most of the previously published theoretical work on this subject, this model provides a much more detailed description of the combustion synthesis process from a microscale point of view, due to the fact that it takes into consideration the various microprocesses, such as the melting of reactants, the diffusion and mixing of reactants, and the formation of products. Different ignition modes, including constant-temperature ignition, constant-heat-flux ignition, and variable-temperature ignition, are considered in this work. The key parameters that influence the ignition process are also discussed.

A micromechanistic model of the combustion synthesis has been extended to study the detailed mechanism and influential parameters of a combustion synthesis process, as well as the development of ignition criteria in the Nb–C system. The case of constant heat-flux ignition conditions has been used to illustrate the details of the ignition process, in order to elucidate the various physical and chemical processes that take place during the initial stages of the combustion synthesis process; however, the results of this study can be generally extended to the other modes of the ignition process. The results showed that the ignition criteria for the Nb–C system corresponded to the establishment of a proper balance between the rates of enthalpy redistribution within the sample, and to the establishment of a kind of positive feedback loop during the ignition process that is necessary for self-propagation to occur. If the heat supplied from an external source to initiate the combustion synthesis process is less than a certain critical value, the combustion wave stops at a certain short distance from the ignition surface. Otherwise, the reaction proceeds in a self-propagating manner.