回転液中紡糸法におけるSn-37 mass%Pb合金細線の断面形状変化

Abstract

It is difficult to produce the continuous fiber of a low surface tension alloy with a round cross-section by using the In-Rotating-Liquid-Spinning process. The relation between the cross-sectional shape of the fiber and the spinning conditions has been examined by using a Sn-37 mass%Pb alloy. The mean mass flow rate of molten metal jet was almost independent of the superheat of the melt. However, the direction of the jet stream became unstable with increasing superheat of the melt and the fluctuation of the jet diameter at the outlet of the nozzle also increased. The roundness of the cross-section of the obtained fiber increased with decreasing ejection pressure, circumferencial velocity of rotating liquid layer, nozzle diameter, jet incidence angle and density of coolant and with increasing superheat of the melt. The fiber with high roundness could be produced, when the inner pressure of jet was higher than the dynamic pressure of coolant acting on the jet at the incidence point of jet into the liquid layer. The computer simulation of the cooling process of jet has been performed in the temperature range from the ejection to the liquidus temperature of the alloy. The average cooling rates were evaluated to be 0.5∼2.4×105 Ks−1, in the water layer, 1.4∼3.0×104 Ks−1 in the methanol layer and 4.7∼6.5×103 Ks−1 in the salad oil layer, respectively. By using methanol and salad oil as a coolant, a more round fiber could be produced, even if the superheat of the melt was low. The double layers, such as the methanol-water layer and the salad oil-water layer, and the triple layer such as salad oil-methanol-water layers were also effective in producing the fiber with round cross-section.