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

采用旋转水旋法制备了贮氢合金细丝。在第一个财政年度，进行了初步试验，以熔化合金样品在喷嘴中的感应加热和喷出熔体通过喷嘴的氩气背压。采用Mm-Ni基合金系统和两种Ti-Zr基合金系统作为试验材料。使用具有0.25mm的嘴直径的石英喷嘴。高频感应加热设备（200 kHz，5 kW）的功率足以熔化Mm-Ni基合金系，但不足以熔化Ti-Zr基合金系。当氩气施加0.35MPa的背压时，Mm-Ni基合金熔体不会从喷嘴喷出。这是由于熔体中存在与石英喷嘴反应形成的段塞。然后，测试了由碳和氧化铝制成的喷嘴。然而，这两种方法对于目前的目的都不能令人满意。理论研究 ...更多信息 对在快淬过程中起重要作用的最小热流点的出现也进行了研究。在第二个财政年度，引进了更大频率（400 kHz，5 kW）的感应加热装置和新的感应线圈。将石英喷嘴的口直径改为0.5mm，试验合金也改为LaNi_5。3g的LaNi_5合金在喷嘴中加热至1450 ℃并完全熔化。然后将其注入到以7 m/s的速度旋转的滚筒的内表面上形成的1.5mm深的水层中并快速固化。产物的几何形状为直径为0.15至0.5 mm的约30 cm长的线、具有不同长度的带或小液滴。获得细线的最佳背压为0.3MPa。产品的PCT图显示出比铸锭更陡的压力平台，并且储氢容量降低到后者的约70%。在石英喷嘴中熔化后逐渐凝固的合金试样，其PCT曲线与产品的PCT曲线相似。对产物进行了SEM观察和ESCA成分分析，结果表明，产物表面形成了2 μm厚的氧化层。不过，这个数量已经足够少了。因此，认为大部分产品在熔化过程中在石英喷嘴中被氧化。根据EPMA分析，在产物的表面处观察到Ni。然而，内部部分的组成与锭相同。这些结果表明，熔体与喷嘴表面的反应应最小化，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