발간논문

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The electrical and thermal fields during a resistance seam welding process for the production of titanium-clad steel plates were numerically analyzed using a finite volume method. Effect of welding parameters such as welding speed, electric current, heating/cooling period, electrode/plate contact area, water cooling intensity, and thermal conductivity of electrode, on temperatures at the bonding layer and titanium surface were studied. With the increase of the water cooling intensity, welding speed, electrode/plate contact area, and thermal conductivity of electrode, temperatures at the bonding layer and titanium surface decreased, but they increased with increasing the heating/cooling period and electric current. Strong cooling, low welding speed, and the use of high thermal-conductivity electrodes were advantageous in preventing oxidation of titanium surface.

keyword : Ti-clad steel plate, Resistance seam welding, Heat transfer, Welding parameter, Numerical analysis, Electrical field, Thermal field

Solvent extraction experiments of FeCl_(3) with Alamine336 salt were performed. It was found from the oading capacity of Alamine336 salt that the solvent extraction reaction depended on the ratio of initial concentration of Alamine336 to FeCl_(3). When the concentration of Alamine336 was in excess compared to that of FeCl_(3), alamine336 participated in the extraction reaction as a dimer. When the initial concentration ratio of Alamine336 to FeCl_(3) was below three, ferric chloride was extracted by monomeric Alamine336. The equilibrium constants of solvent extraction, K_(ex)-2.22×10^(4) and K_(ex)=6.41×10^(5) for monomeric and dimeric Alamine336 respectively, were determined from extraction data by considering activity coefficient of solutes in the aqueous phase. The predicted distribution coefficients of iron agreed well with those experimentally measured.

keyword : FeCl3, Alamine336, HC1, Equilibrium constant, Bromley

Cu films as a seed layer were deposited on Si (100) substrates by applying a negative substrate bias voltage. The electrical resistivity, surface roughness, impurity content and step coverage of the Cu films were investigated using the resistivity measurement, X-ray diffraction analysis, atomic force microscopy, secondary ion mass spectroscopy and scanning electron microscopy. The Cu films deposited at the substrate bias voltage of -50 V showed higher purity, stronger (111) preferred orientation, smoother surface and better step coverage than those of the Cu films deposited without the substrate bias voltage. The electrical resistivity of the Cu films considerably increased as the film thickness decreased. In the case of Cu(100nm)/Ta(50nm)/Si structures, the Cu films deposited by applying the substrate bias voltage maintained a complete (111) preferred orientation without (200) texture even after the thermal annealing at 450℃ for 60 min.

keyword : Copper, Seed layer, Ion bombardment, Resistivity, Substrate bias voltage