Silver metal powders were prepared through reduction of AgNO3 in ethylene glycol using microwave-polyol (M-P) and conventional-polyol (C-P) reactions at 100–200 °C. Powders of Ag were rapidly produced by microwave-assisted reaction at temperatures above 160 °C. The formation yield of Ag powders from AgNO3 reached 97.8% after treatment for 135 min at 140 °C and 98.6% after treatment for 23 min at 160 °C. Compared to the formation of Ag powders using a C-P reaction, a M-P reaction led to increased rate of formation by 6.5 times at 160 °C, 5.2 times at 140 °C, and 3 times at 130 °C. Silver particles of 0.3–2 μm in diameter were produced using M-P and C-P reactions at 100–120 °C. The particle size of Ag powders increased with increasing reaction temperatures and times, and particles strongly aggregated at 160 °C using C-P and M-P reactions.

A two-step heating schedule involving pulse electric current sintering, a kind of pressure-assisted vacuum sintering, and a subsequent postsintering in air was used to fabricate sintered porous alumina compacts. During pressure-assisted vacuum sintering, a dense microstructure of the Al2O3–C system was obtained and in the second stage (i.e., during postsintering in air at different temperatures ranging from 800 to 1300 °C for more than 10 h) carbon particles present in the Al2O3–C system burned out to form a highly porous Al2O3 compact. In this work, the porosity (30%) was successfully controlled and did not change with the postsintering temperature. The intriguing aspect of this study is that porous alumina compacts are fabricated with high strength and remain stable against the postsintering temperature and extended soaking time. This behavior merits the material fabricated here as a potential porous compact, mechanically withstanding for high-temperature applications.

Plastic deformation of amorphous Al90Fe5Gd5 was investigated using nanoindentation and atomic force microscopy. While serrated flow was detected only at high loading rates, shear bands were observed for all loading rates, ranging from 1 to 100 nm/s. However, the details of shear-band formation depend on the loading rate.

The study presents evidence of the microstructural evolution during cyclic indentation of monocrystalline silicon with a spherical indenter. Transmission electron microscopy examination of microindentation on cross-section view samples showed that the structure change in the transformation zone features a decomposition of the amorphous phase to R8/BC8 crystals. Outside the zone, cyclic loading gives rise to bending of pristine silicon, slip penetration, and radial cracking. The development of the load–displacement curves during consecutive indentations is justified in terms of the phase transformation events observed.

Gaseous bubble inclusions in bismuth germanate (BGO) and bismuth germanium silicon oxide (BGSO) crystals were studied by means of Raman spectroscopy at room temperature. Their Raman spectra in the range from 60 to 70 cm−1 showed three peaks for the rotational Raman modes of O2 and N2. Vibrational Raman modes of O2 and N2 were also recorded for BGO and BGSO crystals. It was found that all the rotational and vibrational modes were blue shifted from those of free molecules due to the hydrostatic pressure in the bubbles. Internal pressure in the bubbles was estimated from the rotational and vibrational Raman mode frequencies. O2 gas pressure in the bubble was estimated as 140 GPa, and N2 gas pressure, as 31 GPa. The pressure coefficient of the vibrational mode frequency of O2 (0.368 cm−1/GPa for O2 vibrational mode of 1580 cm−1) and N2 (0.322 cm−1/GPa for N2 vibrational mode of 2331 cm−1) was also obtained from the blue shift and the calculated bubble pressure.

This study presents results of wavelength-dependent Raman scattering from amorphous silicon carbon (a-Si:C:H). The a-Si:C:H films were produced by radio-frequency plasma-enhanced chemical vapor deposition. Prior results with amorphous carbon indicate that laser excitation selectively probes clusters with differing sizes. Our measurements with a-Si:C:H indicate that when using red (632.8 nm), green (514.5 nm), and blue (488.0 nm) excitation, the Raman D and G peaks shift to higher wave numbers as the excitation energy increases. The higher frequency is associated with smaller clusters that are preferentially excited with higher photon energy. It appears that photoluminescence occurs due to radiative recombination from intracluster transitions in Si-alloyed sp2-bonded carbon clusters

The microstructural features of highly damaged 4H–SiC implanted with Al22+ ions at 450 K were studied using transmission electron microscopy (TEM) and electron energy-loss spectroscopy. Conventional TEM images reveal that the crystalline SiC domains are highly strained/distorted when the relative disorder on the Si sublattice ranges between about 0.4 and 0.8, as determined by Rutherford backscattering spectrometry in channeling geometry. As the relative disorder approaches 1.0, the high strain contrast appears to be relieved, and localized amorphized domains are observed. Plasmon-loss energy shows a red shift following the implantation, and the magnitude of the red shift increases with increasing relative disorder. Based on the red shift, the estimated volume expansion is approximately 8% for highly damaged crystalline SiC and approximately 16% for the amorphous state. Energy-loss near-edge-structure of both the C and Si K edge reveals the existence of Si–Si and C–C bonding in the Al22+ implanted SiC.

A silica-colloidal template approach was used to prepare monodisperse nanospheres of TiO2. Close-packed arrays of silica spheres were infiltrated with a sucrose precursor used as a source of carbon. The infiltrated sucrose was carbonized by calcination at 800 °C in flowing argon. After removal of the silica spheres by washing with HF, a porous carbon replica remained. The resulting pores in the replica were then filled with a chloroform solution of titanium alkoxide. Nanospheres of TiO2 approximately 200 nm in diameter were obtained after calcination of the organic component at 600 °C in an argon atmosphere and subsequent sintering in air at 700 °C.

This study evaluated a novel approach for acoustic emission (AE) monitoring of nanoindentation. The technique utilizes a miniature AE sensor integrated into a calibrated diamond indenter tip on a commercial nanoindentation system. The evaluation focused on the yield -point phenomenon in W (100); MgO (100); and sapphire C (0001); R (1012); A (1210); and M (1010) single-crystal surfaces. The minimum amount of elastic energy release sufficient to produce AE signal detectable with the indenter tip sensor was nearly two orders of magnitude lower than the minimum energy level required for conventional AE sensors. Wave forms detected with the indenter tip sensor were independent of sample size. A linear relationship between released elastic energies and the corresponding AE energies was observed for all three evaluated materials. The scaling coefficient of the linear relationship was independent of indenter tip size/shape and indentation depth. The differences between the mechanisms of the initial stages of plasticity for the various crystallographic orientations of sapphire were reflected in the following aspects of AE activity: detection of a specific type of AE wave form that correlated to the presence of linear surface features near the indentation sites; AE signal associated with the yield point, consisting either of one or two distinct wave forms; and presence or absence of AE signals after the yield point. The possibility of plasticity onset in sapphire involving both slip and twinning is discussed.

Ti-peroxy compound was synthesized from Ti(O-iPr)4 and H2O2. Anatase and rutile TiO2 nanoparticles were prepared by heating the Ti-peroxy compound diluted with a polyol aqueous solution at 368 K for 24 h. In this research, ethylene glycol, glycerin, erythritol, and D-mannitol were used as polyols in the diluting solution. The ratio of anatase/rutile of the TiO2 obtained depended on the polyol concentration in the diluting solution. Furthermore, the polyol concentration at which single-phase anatase could be obtained was lowest when the number of OH groups in the polyol molecule was the highest. With increasing polyol concentration, the obtained TiO2 nanoparticles showed increasing specific surface area and decreasing particle size.

Static-gap, single-spark tests were used to investigate the arc erosion behavior of newly developed silicon carbide and alumina particle reinforced silver matrix composites (SiCp/Ag, Al2O3p/Ag). Craters and hills exist on the surfaces of eroded silver matrix composites, and their depths and sizes decrease as the particle content increases and the particle size decreases. Obvious melting, flow, severe splash of molten silver, and the segregation of particles are present on the surfaces of eroded composites containing low volume percents of large particles. Easier silver flow results in smooth surfaces and reduces the total surface areas of the eroded composites containing large particles. The flow and splash of silver decreased with increasing particle content and decreasing particle size, exhibiting a better erosion resistance to single-spark tests. The static-gap, single-spark erosion behavior of silver matrix composites is dominated by the flow and splash of molten composites. A high viscosity of the liquids provides the composites a good arc erosion resistance.

An electroless plating and hot-pressing process was developed to fabricate silver matrix composites reinforced with uniformly distributed graphite and Saffil short fibers (Graphitesf and Saffilsf). The hardness of the composites increases as the content of short fibers increase. Static-gap, single-spark erosion and repeated-collision, multiple-arc erosion tests were used to investigate the arc erosion behavior of the composites. The composites exhibited better arc erosion resistance when the contents of short fibers were increased in a static-gap, single-spark erosion test. However, the weight loss of the composites after 10,000 times repeated-collision, multiple-arc erosion operation shows that the composites with low volume percents of short fibers have a good arc erosion resistance. The Saffilsf/Ag composites show a better arc erosion resistance than Graphitesf/Ag because of the greater strengthening effect of the finer Saffil short fibers. The erosion behavior of the composites is dominated by the viscosity of composites in single-spark tests, while it depends on the competition of viscosity and thermal properties in multiple-arc tests.

Several procedures have previously been advanced for extracting constitutive relations from the force–displacement curves obtained from indentation. This work addresses the specific problem of determining the elastic modulus E, yield stress Y, and hardening exponent n, which define the isotropic strain-hardening model from a single force–displacement curve with a sharp conical tip. The sensitivity of the inversion process was tested through a series of finite element calculations using ABAQUS. Different magnitudes of normally distributed noise were superimposed on a calculated force–displacement curve to simulate hypothetical data sets for specific values of E, Y, and n. The sensitivity of the parameter confidence intervals to noise was determined using the χ2-curvature matrix, statistical Monte Carlo simulations, and a conjugate gradient algorithm that explicitly searches the global parameter space. All three approaches demonstrate that 1% noise levels preclude the accurate determination of the strain-hardening parameters based on a single force–displacement curve.

A laser-based technique was used to deposit Fe3O4 on A319Al, producing an Fe3O4/Al reaction composite coating. Scanning Auger microscopy indicated a reaction between oxide particles and aluminum-forming Fe–Al intermetallic compounds, Al2O3, and various intermediate reaction products. Analysis of the coating region, fractured in vacuo, indicated substantial toughness of the material due to extremely refined microstructure with finely distributed oxide and intermetallic particles and strong interfacial bonding between particles and the matrix. Mechanical properties of the coating were evaluated by nanoindentation techniques employing both Berkovich and cube-corner indenters. Hardness and elastic modulus values were found to be uniform at 1.24 and 76 GPa, respectively. No radial cracking was observed for either the Berkovich or cube-corner indenters. These results indicate that the laser-induced rapidly solidified composite material is tough and fracture resistant.

Electrochemical synthesis of hard Fe–15.4 mass% Ni–0.70 mass% C alloy film with a hardness 750 HV was carried out from sulfate-based bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy was investigated by different characterization techniques including x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Mössbauer spectroscopy, differential scanning calorimetry, and magnetic measurements. The decomposition behavior of the alloy was also studied and compared with that of thermally prepared martensite. It was found that the electrochemically deposited Fe–Ni–C alloy exists in a state that is ahead of the freshly quenched state of martensite. It is suggested that the state of the electrochemically deposited Fe–15.4 mass% Ni–0.70 mass% C alloy corresponds to the state of thermal martensite, which had been heated to the preprecipitation stage of tempering.

Thermal stress characteristics of single-level and two-level Al(Cu) interconnects passivated with tetraethyl orthosilicate oxide were measured using x-ray diffraction. Thermal stresses of the second-level metal lines were deduced from the experimental data based on an analysis of the x-ray absorption in a two-level interconnect structure. The confinement effect from the substrate on the stress characteristics of metal lines at different interconnect levels was investigated. Thermal stress behavior of the second-level lines indicated that the confinement effect from the Si substrate is reduced compared to the single-level lines, resulting in reduced levels of hydrostatic and shear stresses.

Kinetic spray deposition provides a new means for producing composite materials with tailored physical properties. We report on measurements of the thermal conductivity and thermal-expansion coefficient for several compositional variations of kinetically sprayed Al–SiC metal-matrix composites. As a result of the deposition process, inclusion of SiC particles saturates in the 30–40% volume fraction range.

The structure and composition of Cr-nitrides formed on an electroplated hard Cr layer during an ion-nitriding process were analyzed, and its growth kinetics was examined as a function of the ion-nitriding temperature and time to establish a computer simulation model for the prediction of growth behavior of the Cr-nitride layer. The Cr-nitrides formed during the ion-nitriding at 550–770 °C were composed of outer CrN and inner Cr2N layers. A nitrogen diffusion model in the multilayer, based on fixed-grid finite difference method, was applied to simulate the growth kinetics of Cr-nitride layers. By measuring the thickness of Cr-nitride layers as a function of ion-nitriding temperature and time, the activation energy (Q) and nitrogen diffusion constant (Do) were determined for growth of CrN and Cr2N; the result was applied to simulate the growth kinetics of Cr-nitride layers, and reasonable good agreement was obtained with the experimental results.

Giant magnetoimpedance (GMI) and giant stress-impedence (GSI) effects were realized in multilayered FeSiB/Cu/FeSiB films with a meander structure by magnetron sputtering on thin glass substrates. The GMI and GSI effects were studied in the frequency range of 1–40 MHz for the multilayered FeSiB/Cu/FeSiB films. Experimental results show that a large negative GMI ratio of –23% is obtained at Ha=12 kA/m for a frequency of 20 MHz. The GSI ratio is –20% for a frequency of 1 MHz with the deflection of 150μm of the multilayered FeSiBsCu/FeSiB films. The GSI effect is attractive for stress or pressure sensor applications.

High critical current density (high-Jc) YBa2Cu3O7–δ (YBCO) films were obtained by pulsed laser ablation on biaxially textured Cu substrates. To achieve epitaxy of LaMnO3 (LMO) on Cu, thin epitaxial Ni overlayers were deposited on Cu tapes. The structure comprises the layer sequence of YBCO/LMO/Ni/Cu. For 200-nm-thick YBCO, self-field Jc values exceeding 1 × 106 A/cm2 at 77 K were achieved. Characterization of these short prototype conductors revealed good structural and morphological properties. Magnetic analysis suggested that hysteretic loss due to the ferromagnetic Ni overlayer is minimal.