Thin films of poly(methyl methacrylate)–multiwalled nanotubes composites were produced by spin coating using different nanotube concentrations. The materials were characterized by scanning electron microscopy, energy-dispersive x-ray analysis, and Raman spectroscopy to obtain information on the possible interactions between the constituents and to control the homogeneity of the films. Electrical conductivity measurements of the composites, as a function of the nanotube concentration, show a percolation threshold at very low concentration. Also, the J–E characteristics exhibits a nonlinear behavior at low concentration, becoming linear far above the threshold.

Arrays of Cu/Cu2O nanowires were grown by electrodeposition in the nanopores of track-etched polymer membranes. If an appropriate solution is used, the electrode potential spontaneously oscillates during the application of a constant cathodic current. Both the period of the oscillations and the composition of the nanowires can be controlled by varying the applied current density. A nanocomposite of copper and cuprous oxide is deposited at an applied current over which oscillations occur. In contrast, pure Cu or Cu2O nanowires are obtained at a deposition current out of the range of oscillation. Electrical transport measurements were also performed on these nanowires.

The kinetics of the formation of PbTiO3 at the PbO/TiO2 interface has been analyzed. The flux of Pb2+ and O2− ions through the PbTiO3 layer was used to derive the kinetics equation for the formation of the PbTiO3 phase. On the basis of the parabolic growth kinetics of the PbTiO3 interlayer, the reaction rate constant (k) for PbTiO3 formation was determined as a function of the average diffusion coefficient of the Pb2+ ions (DPb2+). By employment of the data from diffusion couple experiments and the free energy values for the formation of the PbTiO3 phase () into the present kinetics equation, DPb2+ in the PbTiO3 interlayer was calculated with respect to the corresponding temperature. The activation energy for diffusion (Q) and the diffusion constant (D0) of Pb2+ ions in the PbTiO3 layer could be evaluated from the Arrhenius plot of DPb2+.

Carbon fiber surfaces were analyzed by inverse gas chromatography (IGC) and x-ray photoelectron spectroscopy (XPS). IGC measurements were carried out at infinite and finite dilution by using neutral and specific probes. At infinite dilution the dispersive component of the surface free energy and the acid–base indexes were obtained. At finite dilution the energy distribution functions were calculated. Three carbon fibers were analyzed, one untreated and two fibers treated with different sizings. The fibers have similar dispersive components of surface free energy but their acid–base characteristics are markedly different. The untreated fiber has an acidic surface, and the sized fibers have a surface with high base character. The energy distribution functions show different peaks assigned to active sites existing on the carbon fiber surfaces. The use of acid or basic probes provides different energy distribution functions with good correlation with the base and acid character of the fiber surface. Changes in surface heterogeneity revealed by energy distribution functions were correlated also with surface chemical composition derived from high-resolution XPS measurements.

The effects of energetic treatments, crosslinking, and plasma modification on the surface mechanical properties and deformation behavior of ultrahigh molecular weight polyethylene (UHMWPE) were examined in light of nanoindentation experiments performed with a surface force microscope. Samples of UHMWPE were subjected to relatively high-dose gamma irradiation, oxygen ion implantation, and argon ion beam treatment. A range of crosslinking was achieved by varying the radiation dose. In addition, low-temperature plasma treatment with hexamethyldisiloxane/O2 and C3F6 was investigated for comparison. The surface mechanical properties of the treated UHMWPE samples are compared with those of untreated UHMWPE samples used as controls. Surface adhesion measurements obtained from the nanoindentation material responses are also discussed in terms of important treatment parameters. Results demonstrate that high-dose oxygen ion implantation, argon ion beam treatment, and low-temperature C3F6 plasma modification are effective treatments for enhancing the surface mechanical properties of UHMWPE.

Template-directed co-condensation was used to synthesize phenyl-modified MSU-1 and bi-functionalized MSU-1 silica containing binary moieties of covalently linked phenyl along with methyl or ureidopropyl [H2NCONH(CH2)3]. The texture properties of these materials from x-ray diffraction, Fourier transform infrared, nuclear magnetic resonance, scanning electron microscopy, high-resolution transmission electron microscopy, N2 adsorption, thermogravimetric analysis data, varied with the type of alkoxylsilane precursor and the amount of organosiloxane in the mixture. Small-angle x-ray scattering results, for the as-synthesized and surfactant-extracted organo-modified MSU-X, showed that the templates remaining in the mesostructures gave positive deviation from Porod's law while the incorporated organic groups led to a negative deviation, which formed an interfacial layer between the pore and silica matrix.

The results of the development and characterization of a new relaxor ceramic with nominal composition (x)Pb2(In,Nb)O6(1 − x)Pb(Mg1/3Nb2/3)O3 solid solution with x = 0.4 are reported. The structural characteristics, including the long-range and short-range order, forbidden reflections, and the existence of mixed ordering, were studied by transmission electron microscopy. The most prominent microstructural feature of this compound, which has composition variations in the micro- and nano-regions, was investigated. The presence of the pyrochlore phase and the complex arrangement of inclusions that originate from processing are illustrated. The electrical characteristics of the compound including pyroelectric, piezoelectric, electrostrictive and hysteresis properties are reported. Notable properties of the compound include a reduced hysteresis loop and nonlinear behavior at high field.

This paper summarizes the effects of selected processing parameters on the behavior of aqueous alumina suspensions during hydrolysis-assisted solidification and on the properties of the green and sintered parts prepared by this technique. Measurements of the changes in viscosity, the pH, and the impedance of aqueous suspensions with time were performed to evaluate the process. Using impedance spectroscopy, the effects of the addition of AlN, the solids content in the ceramic suspension, and the effect of the solidification temperature on the progress of solidification were followed. It was demonstrated that the solidification temperature significantly affects not only the solidification rate but also the properties of the green and sintered parts. A transmission electron microscopy analysis of dry green parts revealed that the host ceramic particles are bound by a predominantly amorphous AlOOH phase, which results in a high strength for the green parts.

Diamondlike carbon (DLC) films were grown on Si and ceramic substrates by very-high-frequency chemical vapor deposition at temperature of approximately 250 °C. Thin metal coatings from Ti, Ni, Pt, and Cu were deposited on the substrates before DLC film deposition. The impact of the pregrowth treatments of the substrates on surface morphology and emission properties of the grown DLC films was studied. The films deposited on ceramic substrates pretreated by Ti, Ni, and Pt coatings, with grainlike structures, demonstrated good emission currents and low threshold voltages among the deposited DLC films.

The dielectric properties of the Ba(Ti1–xZrx)O3 (BT1–xZx) ceramics with various compositions were investigated under various DC bias fields. In BT0.94Z0.06 ceramics, the dielectric constants (ε) vs temperature (T) curves without DC bias showed no frequency dependence. Its DC bias dependence exhibited that with increasing DC bias fields, the dielectric constants were suppressed while phase transition peaks slightly shifted to high temperature. In BT0.58Z0.42 ceramics, the ε vs T curves without DC bias showed a broad peak with a clear frequency dependence, which revealed that BT0.58Z0.42 ceramics were the relaxor. Its DC bias dependence exhibited that with increasing DC bias fields, the dielectric constants were suppressed while the phase transition peak largely shifted to low temperatures. In BT0.79Z0.21 ceramics, the ε vs T curves without DC bias showed a broad peak without frequency dependence. Its DC bias dependence revealed that the dielectric peak shifted to high temperature and broadened with increasing DC bias. To explain the above phenomena, it was considered that the role of Zr ions on BT1−xZx ceramics is to make the depth of the potential well shallow successively.

The effects of the active and passive protection mechanisms of powder beds on the sintering of Si3N4 were investigated. Shrinkage, density, and coloring behavior of sintered samples were analyzed using different compositions and packing conditions of powder beds based on BN and Si3N4 with different additives. Y2O3 additive in the powder bed influences the weight change and phase formation behavior of the samples, although it has a very low vapor pressure at the sintering temperature. When MgO/Y2O3 was used as sintering additives, the packing density and thickness of the powder bed had a much stronger effect than in the case of Al2O3/Y2O3. For the optimization of the powder bed conditions, the vapor pressure and chemical stability of sintering additives at the sintering temperature has to be considered.

Materials formed from micro- and nanoscale particles are of interest because they often exhibit novel optical, electrical, magnetic, chemical, or mechanical properties. In this work, a means of constructing particulate materials using DNA strands to selectively attach micro- and nanoparticles to substrates was demonstrated. Unlike previous schemes, the DNA was anchored covalently to the particles and substrates, rather than through protein intermediaries. Highly reproducible selective attachment of 0.11–0.87 mm-diameter particles was achieved, with selective:nonselective binding ratios >20:1. Calculations showed that at most 350 and 4200 DNA strands were involved in the binding of the small and large particles, respectively. Experiments showed that the DNA was bent at an angle, relative to the surfaces of their solid supports.

Hexagonal 6H– and 4H–SiC wafers were implanted with (1−1.5) × 1016 cm−2 germanium ions at room temperature and at 700 °C with subsequent annealing between 1000 and 1600 °C. Structural changes in the SiC matrix were studied in detail by means of transmission electron microscopy (TEM). After implantation at room temperature the hexagonal SiC matrix becomes amorphous and, after annealing, recrystallizes into cubic SiC. The latter process was accompanied by the creation of voids and cracks. In case of high-temperature (700 °C) implantation, where amorphization was avoided, no polytype change in as-implanted and annealed SiC wafers was observed. In annealed samples nanocrystalline precipitates with high Ge content were observed in high-resolution TEM images.

A solution of a polymeric precursor for silicon carbide (SiC) was subjected to electrostatic atomization in the cone-jet mode to spray droplets on a zirconia substrate. The resulting deposit was heated to 1300 °C to obtain SiC relics. Precursor and ceramic relics were characterized by microscopy. The size distribution of the droplet relics was studied at several flow rates of the solution to the electrostatic atomization chamber. The results show that by controlling the flow rate SiC relics approximately 5 μm in diameter can be produced.

The sliding friction and wear performance of Al–Ni–Co–Si quasicrystalline coatings deposited by the high-velocity oxy-fuel technique were investigated under dry sliding conditions. This study indicated that changes in the imposed sliding test conditions modified the friction and wear behavior of quasicrystalline coatings. Qualitative analysis of the contact interface and wear debris were performed with the aim of understanding the role of the third body on the friction and wear processes. The dependence of the coefficient of friction on the sliding velocity and counterpart material was explained by the stick-slip behavior. It was also shown that test conditions favorable for the formation of thick intermediate layers and the densification of the coating subsurface led to low wear rates. Large cylindrical particles, formed by agglomeration of small wear debris, were suggested as a beneficial factor for the reduction of the coefficient of friction.

Various methods to access indentation data are considered on the basis of the load P–displacement h curve, its derivative, or its integral. This paper discusses and extends the various analytical models to estimate the indentation P–h curve, the slope, and the dissipated energy to aid the development of a concise methodology to analyze indentation data. Special consideration is given to the effect of pile-up and sink-in. Relationships for sharp and spherical indenters are presented and in addition for sharp indenters with a rounded tip. An overview over analytic expressions for the P–h curve is given and compared to finite element simulations and experimental data. An expression derived for the representative strain at the onset of yield under sharp and spherical indenters compares well with literature results. The effect of a rounded tip on the yielding under a sharp indenter is discussed. The ratio of loading to unloading slope and the ratio of the plastically dissipated energy to the total energy is related to hardness and elastic modulus. In combination these ratios can be used to determine the strain-hardening coefficient.