Zone Refining of Aluminum and Its Simulation

Abstract

Ultrahigh-purity aluminum with a residual resistivity ratio (RRR) of 6000065000 was obtained by the ultrahigh-vacuum melting method. However, it was necessary to reduce the concentration of the elements with distribution coefficient k > 1 to further improve the purity of aluminum. Therefore, we prepared a sample with reduced concentrations of k > 1 elements from an ultrahigh-purity (99.9999%) aluminum material by the zone-refining method, and evaluated its purity by electrical resistance measurement and glow discharge mass spectrometry (GDMS). In addition, the zone-refining process was simulated, and the distribution of the solute atoms after approximately 10 passes of zonerefining was predicted. Moreover, the refining conditions were investigated with the aim of achieving higher purity. In experiments, when the zone width was increased from 60 to 80 mm at a zone speed of 60 mm/h, the concentrations of the elements with k > 1 in the second half of the material decreased and RRR improved. When the zone speed was decreased to 30 mm/h, a marked effect was observed and RRR increased to about 85000. The distribution of the solute atoms determined from the simulation was in good agreement with the results of GDMS analysis, thus confirming the usefulness of the simulation.

Laser heating, zone refining, titanium

“…6. The tendency that the content of the impurity decreases obviously at the starting position, keeps steady at the middle and rapidly rises at the end is in good agreement with other literatures [5,21] . The concentration of Fe decreases by 48.8% at the beginning of the sample and rise highly at the end, which means cutting the tail can acquire the high purity Ti.…”

Research Status of High-Purity Metals Prepared by Zone Refining

“…Nakamura et al [55] proposed a numerical simulation model that divides the melting into two independent regions, namely the diffusion region and the stirring region, as shown in Figure 13a, and the vertical axis C represents the solid and liquid. There is an interface between them, and there are diffusion regions and stirring regions in the molten region.…”

Characterization and Interpretation of the Aluminum Zone Refining through Infrared Thermographic Analysis

“…The purification takes place by redistributing the impurities at the freezing interface when one or a series of molten zone(s) move through a solid bar. Many experimental and theoretical investigations have been conducted in recent decades with focus on improving refining and/or production efficiencies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Two general categories, as characterized by different emphases, can be summarized from these investigations.…”

“…The first is in realizing the target within the frame of the impurity distribution profile by optimizing experimental parameters such as zone length, zone movement velocity, number of passes, etc. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. The second is a focus on knowledge of the molten zone, such as zone shape, zone length variation, and the position of the molten zone, by taking heat transfer and heat balance into consideration [ 11 , 12 , 13 , 14 , 15 ].…”