REPARATION OF FINE WIRES OF HYDROGEN STORAGE ALLOY WITH FINE CRYSTAL GRAIN BY THE IN-ROTATING-WATER SPINNING METHOD

采用旋水纺丝法制备了储氢合金细丝。在第一个财政年度，进行了初步试验，通过感应加热将合金样品熔化在喷嘴中，并通过氩气背压将熔体喷出喷嘴。采用一种Mm-Ni基合金体系和两种Ti-Zr基合金体系作为试验材料。采用直径为0.25 mm的石英喷嘴。高频感应加热装置（200khz, 5kW）的容量足以熔化Mm-Ni基合金体系，但不足以熔化Ti-Zr基合金体系。当氩气的背压为0.35 MPa时，Mm-Ni基合金的熔体没有从喷嘴喷出。这是由于与石英喷嘴反应形成的熔体中存在塞状物。然后，对碳和氧化铝制成的喷嘴进行了测试。然而，对于目前的目的来说，这两种方法都不令人满意。对快速淬火过程中起重要作用的最小热通量点的出现进行了理论研究。在第二个财政年度，引入了频率更高（400千赫，5千瓦）的感应加热装置和新的感应线圈。石英喷嘴的口径改为0.5 mm。试验合金也改为LaNi_5。将3 g LaNi_5合金在喷嘴中加热至1450℃，完全熔化。然后将其注入以7 m/s速度旋转的滚筒内表面形成的1.5 mm深的水层中并迅速固化。产品的几何形状为直径为0.15 ~ 0.5 mm的长约30厘米的电线、不同长度的带状或小液滴。获得细丝的最佳背压为0.3 MPa。产品的PCT图显示出比铸锭更陡峭的压力平台，储氢容量下降到铸锭的70%左右。在石英喷嘴中先熔融后逐渐凝固的合金样品，其PCT图与该产品相似。产物的SEM和ESCA组成分析表明，表面形成了2 μm厚的氧化层。然而，这个数量已经足够小了。因此，在熔融过程中，大部分产品被认为在石英喷嘴中被氧化。根据EPMA分析，在产品表面观察到Ni。但内部成分与铸锭相同。这些结果表明，应尽量减少熔体与喷嘴表面的反应，以防止PCT特性的恶化。少

Studies were conducted to prepare a fine wire of hydrogen storage alloy by the In-Rotating-Water Spinning Method. In the first fiscal year, preliminary tests were conducted to melt alloy samples in a nozzle by induction heating and to eject the melt through the nozzle by argon back pressure. A Mm-Ni based alloy system and two Ti-Zr based alloy systems were employed as the test materials. A quartz nozzle with the mouth diameter of 0.25 mm was used. The capacity of a high-frequency induction heating apparatus(200 kHz, 5kW) was large enough to melt the Mm-Ni based alloy system but it was not enough for the Ti-Zr based alloy systems. The melt of Mm-Ni based alloy did not eject through the nozzle when the back pressure of 0.35 MPa was pressed by argon gas. This was due to the existence of slug in the melt formed by the reaction with the quartz nozzle. Then, nozzles made of carbon and alumina were tested. However, both of them were not satisfactory for the present purpose. A theoretical stud … More y on the occurrence of the minimum-heat-flux point that plays an important role during the rapid quenching process was also conducted. In the second fiscal year, an induction heating apparatus with a larger frequency(400 kHz, 5 kW) and a new induction coil were introduced. The mouth diameter of the quartz nozzle was changed to 0.5 mm. The test alloy was also changed to LaNi_5. The LaNi_5 alloy of 3 g was heated to 1450 ℃ in the nozzle and was completely melted. Then it was injected into the water layer of 1.5 mm in depth that was formed on the inside surface of a drum rotating at a velocity of 7 m/s and rapidly solidified. The geometrical shape of the product was about 30-cm long wires of 0.15 to 0.5 mm in diameter, ribbons with different lengths, or small droplets. The optimum back pressure for obtaining a thin wire was 0.3 MPa. The PCT diagram of the product showed a steeper pressure plateau than the ingot and the hydrogen-storage capacity decreased to about 70% of the latter. It was also found that the sample of alloy that was melted and then solidified gradually in quartz nozzle showed the PCT diagram similar to that of the product. The SEM view and the composition analysis by ESCA of the product showed that 2 μm thick layer of oxide was formed on the surface. However, this amount was small enough. Thus the bulk of the product was considered to be oxidized in the quartz nozzle during the melting process. According to the EPMA analysis, Ni was observed at the surface of the product. However, the composition of inner part was the same as the ingot. These results indicated that the reaction of the melt with the nozzle surface should be minimized to prevent the deterioration of the PCT characteristics. Less