帯域熔融法による錫および鉛の精製

抄録

Twenty molten zones were passed on lead and tin bars, which were vacuum-sealed in glass tubes. The refining effect and the impurity distribution were estimated from intensity measurement of the emission spectrum. It was confirmed that zone-refining was effective for Pb and Cu in Sn; Cu and Ag in Pb. But we could not observe the refining effect for Bi in Sn; therefore, another method must be found in order to remove Bi in Sn. The highest purity was usually found at nearly middle but a little closer to the top portion. Adding one per cent of 4-nine-purity lead to the zone-refined purest lead, we could observe a clear difference in microstructure of quenched specimens from molten state. It was concluded that purity was improved by two orders, from 4-nine to 6-nine, — at least in respect of those impurities which had effects on quenched structure. This improvement in purity was endorsed by the results of spectrum analysis.