Interfacial structure and reaction mechanism of AlN/Ti joints

Bonding of AlN to Ti was performed at high temperatures in vacuum. The bonding temperature ranged from 1323 to 1473 K, while the bonding time varied from 7.2 up to 72 ks. The reaction products were examined using elemental analysis and X-ray diffraction. TiN, Ti3AlN (τ1), and Ti3Al were observed at the AlN/Ti interface, having various thickness at different bonding conditions. The thickness of TiN and Ti3AlN layers grew slowly with bonding time. On the other hand, growth of the Ti3Al layer followed Fick’s law. The activation energy of its growth was found to be 146 kJ mol-1. When thinner Ti foil (20 μm) was joined to AlN at 1473 K for a long time (39.6 ks), the Ti central layer has completely consumed and another ternary compound Ti2AlN(τ2) started to form. A maximum bond strength was achieved for an AlN/Ti (20 μm) joint made at 1473 K for 28.8 ks, after which the bond strength of the joint deteriorated severely. This revised version was published online in November 2006 with corrections to the Cover Date.     

A NUMERICAL SIMULATION OF SWIRLING FLOW PNEUMATIC CONVEYING IN A HORIZONTAL PIPELINE

ABSTRACT

A numerical simulation for swirling and axial flow pneumatic conveying in a horizontal pipe was carried out with a Eulerian approach for the gas phase and a stochastic Lagrangian approach for particle phase, where particle-particle and particle-wall collisions were taken into consideration. The k-? turbulence model is used to characterize the time and length scales of the gas-phase turbulence. Models are proposed for predicting the particle source and additional pressure loss. The numerical results are presented for polyethylene pellets of 3.1 mm diameter conveyed through a pipeline of 13 m in length with an inner diameter of 80 mm, solid mass flow rate was 0.084 kg/s, and gas velocity was varied from 10 m/s to 18 m/s. The particle flow patterns, the particle concentration and the particle velocity, and additional pressure loss were obtained. It is found that the particle velocity and concentration has almost same value along flow direction in swirling flow pneumatic conveying. The profile of particle concentration for swirling flow pneumatic conveying exhibits symmetric distribution towards the centerline and the higher particle concentration appears in neighbor of wall in the acceleration region. At downstream, the uniform profile of particle concentration is observed. The particle velocity profile, on the other hand, is uniform for both swirling and axial flow pneumatic conveying. A comparison of the calculations with the measured data shows a good agreement within an average error of less than 15 percent.     

Thermal Conductivities of As-Se Glasses

The thermal conductivities of As-Se glasses (0 to 50 at.% As) were measured by a comparative continuous-heating method from room temperature to above the glass transition. Thermal conductivity increased slowly with increasing temperature, then, in the transition region, decreased suddenly, reaching minimum values. Thermal conductivity at 40°C, as a function of composition, exhibited a maximum at 40% As.     

The Effect of Annelation on the Colour of 1, 4-Disubstituted Benzoanthraquinone Disperse Dyes

The visible spectra of a series of 1,4-disubstituted benzoanthraquinone dyes in benzene solution has been measured. The position of the absorption maxima of the dyes has been found to be well correlated with a mean ionization potential of the substituent groups. An annelation of anthraquinone dyes in the position of 2, 3 or 6, 7produced a small hypsochromic shift, while 5,6-annelation produced a large bathochromic shift. The additive properties on the absorption maximum of dibenzoanthraquinone dyes were also observed.     

Wavelet Multi-Resolution Cross-Correlation Analysis of Swirling Gas-Solid Flow in a Horizontal Pipe

A wavelet multi-resolution cross-correlation analysis was developed and applied to experimental pressure-time signals in order to analyze the characteristics of swirling gas-solid flow in both Fourier and physical spaces. The experiment was carried out in a horizontal pipe with a length of 7.5 m and an inner diameter of 76 mm. The initial swirl number based on the total inflow was varied from 0.0 to 0.61, the mean gas velocity was varied from 6 to 28 m/s, and the solid mass flow rate was varied from 0.08 to 0.5. From the wavelet multi-resolution correlation analysis of the fluctuating pressure in the range of low air velocity, the characteristics of swirling gas-solid two-phase flows were extracted at various frequencies. Much stronger correlations were found in the range of low frequency, which implied periodic motion of dunes and sliding clusters. Additionally, it was revealed that the motion of a large cluster sliding flow contains two smaller clusters and the moving velocities of dunes were 1 m/s and 2 m/s, respectively. However, no correlation existed at smaller scales of correlation features, which indicated heterogeneous suspension flow.     

Gelation of Bovine Serum Albumin by Glutathione

Bovine serum albumin (BSA) formed an opaque gel when incubated at 37°C with reduced glutathione (GSH). Gelation was highly dependent on concentration of GSH and pH, at 70 mM GSH and pH 8.2 BSA showed maximum gel hardness. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and the number of protein sulfhydryls revealed that gelation involves reduction of intramolecular disulfides in BSA and subsequent cross-links through intermolecular protein disulfides. Gelation was strongly inhibited by high concentrations of salts; inhibitory effects were highly dependent on species of anions, but not cations.     

Lead Zirconate Titanate Film Formation Technology with Use of Spray Coating Method

This paper presents a three-dimensional microfabrication and integration technology for MEMS smart materials that utilizes a spray coating method. Spray coating is shown to be most effective for additional deposition on non-planar surfaces. PZT films were formed both on flat and uneven surfaces at a thickness of about 1μ m. Perovskite structures were formed with suitable heat treatment and ferroelectric P-E hysteresis loop was also obtained. This paper is the first report from our group and other researchers on the deposition of smart materials for MEMS using a spray coating method. Spray coating has been proposed as an effective three-dimensional coating method which can be used to deposit piezoelectrics, pyroelectrics, magnetics, etc. for sensors and actuators. The hydrophilic and hydrophobic properties between the substrate surface and ejected liquid are most essential process factors in the spray coating method for improving the film growth conditions.     

EFFECT OF ALKYL CHAIN LENGTH OF 3-ALKYLPENTANE-2, 4-DIONE ON THE EXTRACTION OF COPPER

The equilibrium and kinetics of the extraction of copper with 3-alkylpentane-2, 4-dione (-H, -C₂H₅, -Ph, and -C₈H₁₇) were studied. It was found that the overall equilibrium constant is related to the proton disscoiation constant and that the ratio of the stability constants of the copper chelate, β₂/β₁ ²was independent of the alkyl chain length of the β-diketone. The rate constants for the reactions between cupric ion and the β-diketones in the aqueous phase were obtained by the relaxation method. The values decreased in the order -H>-Ph>-C₂H₅. The observed extraction rates were explained by a kinetic model using the measured physicochemical properties.     

Quality Evaluation of Fish Meat by 31 Phosphorus-Nuclear Magnetic Resonance

³¹Phosphorus-Nuclear Magnetic Resonance (³¹P-NMR) was used to evaluate degree of freshness of loach muscle depending on metabolic changes of high energy phosphate compounds. The phosphocreatine ([PCr])/inorganic phosphate ([Pi]) ratio was found to be a sensitive index of early metabolic hypofunction. Ratios of [PCr]/β-phosphate of ATP ([β-ATP]), and [Pi]/[β-ATP] were demonstrated to be appropriate indexes to estimate such metabolic changes in fresh fish. The intramuscular levels of creatine phosphate, ATP and pH were maintained at higher levels in blood-drained loach than in untreated fish. The freshness of fish which were bled and washed at lower temperatures were better preserved.     

Numerical Study of Air Compressibility During Horizontal Pneumatic Transport

Using numerical simulations, the effect of the compressibility of air on the flow pattern of particles and pressure drop in the presence of particles during horizontal pneumatic transport operating under negative pressure was examined. The length and inside diameter of the pipeline were 30 m and 40 mm, respectively, and the chosen particles (4 mm in diameter) had densities of ρ_p = 1000 and 2000 kg/m³. The mean air velocities at pipe the inlet were U_inlet = 19, 22, and 28 m/s, and the range of the mass flow rate ratios of particle to air, μ, was varied up to 2.0. For a given inlet air velocity, the difference in the flow pattern between compressible and incompressible flow calculation is generally small. For ρ_p = 1000 kg/m³ particles the additional pressure drop in compressible flow increases when μ is above 0.5 and U_inlet is 28 m/s, μ is above 1.3 and U_inlet is 22 m/s, and μ is above 1.5 and U_inlet is 19 m/s. In these cases, the particle flow pattern is homogeneous. For ρ_p = 2000 kg/m³ particles, the pressure drop increases only when μ is above 1.5 and U_inlet is 28 m/s. The difference is not noticeable when the particle flow pattern is heterogeneous. Also, the difference in the additional pressure drop is much larger during homogeneous flow than heterogeneous flow.