CHANGE OF CROSS-SECTIONAL SHAPE OF SN-37 MASS-PERCENT-PB ALLOY FIBER IN THE IN-ROTATING-LIQUID-SPINNING PROCESS

It is difficult to produce the continuous fiber of a low surface tensi on alloy with a round cross-section by using the In-Rotating-Liquid-Sp inning process. The relation between the cross-sectional shape of the fiber and the spinning conditions has been examined by using a Sn-37 m ass%Pb alloy. The mean mass flow rate of molten metal jet was almost i ndependent 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 i ncreased. The roundness of the cross-section of the obtained fiber inc reased with decreasing ejection pressure, circumferencial velocity of rotating liquid layer, nozzle diameter, jet incidence angle and densit y 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 i ncidence point of jet into the liquid layer. The computer simulation o f the cooling process of jet has been performed in the temperature ran ge from the ejection to the liquidus temperature of the alloy. The ave rage cooling rates were evaluated to be 0.5 similar to 2.4 x 10(5) Ks( -1), in the water layer, 1.4 similar to 3.0 x 10(4) Ks(-1) in the meth anol layer and 4.7 similar to 6.5 x 10(3) Ks(-1) in the salad oil laye r, 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 l ow. 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-se ction.