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Axial and radial distributions of gas holdup and liquid velocity were studied in a gas-liquidsolid fluidized bed of 0.12 m i.d. Air, water and glass beads (0.58, 1.2 and 2.2 mmin diameter) were used as gas, liquid and solid particle phases, respectively. Local gas holdup was meaured by using an electric conductivity probe, and local liquid velocity was obtained by the electrolyte tracer method. The value of local gas holdup was in proportion to the square of the distance from the column wall. The liquid flow pattern was similar to that of the bubble column, showing an up-flow in the central region and a down-flow in the peripheral region with respect to the interstitial mean liquid flow. Liquid velocity at the central axis increased with increasing superficial gas velocity and with decreasing particle diameter. The results were analyzed on the basis of the circulating flow model, where a constant turbulent viscosity and a constant composition of the liquid-solid mixtures were assumed. The turbulent viscosity for fully developed fluidization was correlated as a function of particle diameter and superficial gas velocity, and was compared to that of the bubble column.

The market for wearable devices has increased considerably in recent years. In response to this demand, flexible electronic circuit technology has become more important. The conventional bonding technology in electronic assembly depends on high-temperature processes such as reflow soldering, which result in undesired thermal damages and residual stress at a bonding interface. In addition, it exhibits poor compatibility with bendable or stretchable device applications. Therefore, there is an urgent requirement to attach electronic parts on printed circuit boards with good mechanical and electrical properties at room temperature. Nanowire surface fasteners (NSFs) are candidates for resolving these problems. This paper describes the fabrication of an NSF on a flexible substrate, which can be used for room temperature conductive bonding. The template method is used for preparing high-density nanowire arrays. A Cu thin film is layered on the template as the flexible substrate. After etching the template, a Cu NSF is obtained on the Cu film substrate. In addition, the electrical and mechanical properties of the Cu NSF are studied under various fabrication conditions. The Cu NSF exhibits high shear adhesion strength (∼234 N cm) and low contact resistivity (2.2 × 10 Ω cm).

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