On Floating Zone Melting of High Purity Iron

Abstract

A study was made of the refining conditions for obtaining high purity iron from re-electrolytic iron by the floating zone melting technique. The main results obtained are summarized as follows:
(1) The effect of the specimen diameter on the zone refining was not recognized in a range from 5 to 25 mm dia.
(2) The later the travelling rate or the more the number of passage was, the greater the zone refining effect was.
(3) A multiple zone refining which was alternately melted in dry H2 and wet H2 wasvery effective, and after seven zone passes in dry H2, wet H2 and vacuum the specimen showed the lowest value of resistance ratio (R_4.2°K/R₂₉₅°K=1/210).
(4) From the zone refined specimen, only Co, Cu, Ni and Si were detected as the remained metallic impurities. O and N were effectively removed by zone melting in dry H₂and wet H₂, but C was hardly removed even in wet H₂.°(5) The overlap method was found to be effective technique, as compared with an usually zone re fining method, for multiple zone refining to protect “melt in” or diffusion of impurities from the unpuri fied section adjacent to the starting end.