Zone refining of 99.99999 % aluminum and the enlargement

用旋转泵(CRYO-U6)和辐射温度计(IR-AQITG-I型)构成了一种半自动区域细化装置。可在稳定条件下长期使用。该装置的极限压力为2.7x10^-8；pa。在高温下，由于从石墨中释放出大量气体，设备的真空度变差。然而，通过在操作前从船上烘烤，可以在真空度为1x10^-7&gt；pa的条件下对铝进行区域精炼。使用该装置，对标称纯度为99.999%的铝进行了区域精炼。熔区长度为3 cm，移动速度为5.5 cm/h。区域传球重复10次。得到的铝表面覆盖着一层薄薄的氧化膜，具有金属的光泽，与用油扩散泵进行区域细化相比，测量了剩余电阻率比(R_&lt；300K&gt；/R_&lt；4.2K&gt；)，以检验区域细化的效果。在精炼块体的顶端，这一比率约为2×10~(-4)，但在末端，这一比率突然下降。原因可能是当时石墨舟或石英管的污染，因为铝表面的氧化膜很薄。用四极质谱计对区域精炼过程中的气氛进行了分析，识别出了H2、H2O、CO、CO2和氢碳。用本装置精炼的铝的氢释放量是用油扩散泵精炼的铝的一半，因此使用低温泵可以有效地去除气体杂质。目前尚不能成功地获得99.99999%的铝，但通过对铝、石墨舟、石英管等原料的选择，相信可以达到纯度。

A semi-automatic zone-refining apparatus was constructed with a cyro-pump (CRYO-U6) and a radiation thermometer (IR-AQITG type I). It is available to use under a stable condition for a long time. The ultimate pressure of this apparatus is 2.7x10^<-8> pa. Vacuum of the apparatus becomes to worse at a high temperature by release of a lot of gas from a graphite. However, it is possible to perform zone refining of aluminum under vacuum of 1x10^<-7> Pa, by baking out of the boat before the operation.Using this apparatus, zone-refining of aluminum with a nominal purity of 99.999 % was performed. Length and the traveling speed of the molten zone were 3 cm and 5.5 cm/h, respectively. Zone passing was repeated 10 times. The surface of aluminum thus obtained was covered with a thin oxide film, and has a metallic brightness, comparing with one zone-refined using an oil diffusion pump.Residual resistivity ratio (R_<300K> /R_<4.2K> ) was measured to check the effect of zone refining. The ratio was about 2x10^4 at the top end of the refined block, but it decreased suddenly for the tail end. The reason may be a contamination from then graphite boat or the quartz tube, because the oxide film on the surface of aluminum is thin. Atmosphere during then zone refining was analyzed with a quadrupole mass spectrometer, and H_2, H_2O, CO, CO_2, and hydro-carbon were recognized. Amount of hydrogen released from the aluminum refined by the present apparatus becomes a half of that from aluminum refined using an oil diffusion pump, therefore the use of cryo-pump is effective to eliminate gas impurities. It is not succeeded to get 99.99999 % aluminum at the present, but it is believed to attain the purity by the selection of original material of aluminum, graphite boat and quartz tube, etc.