Manufacturing Method of High Purity Iron by Zone Refining and the Measurement of the Purity

Abstract

High purity iron was manufactured by zone refining under wet and dry hydrogen atmospheres.
The original materials were reelectrolytic iron, a common specimen of the Iron and Steel Institute ofJapan (specimen number 958, 960), Johnson Matthey iron, and Puron iron. The residual resistivityratio (RRR) was used to show the purification degree and the longitudinal magneto-resistance effect wasinvestigated at 4.2°K.
As one of the physical properties, the thermoelectromotive force (EMF) was studied and the relation between EMF and RRR was investigated.
The results were summarized as follows:
(1) The slower the travelling rate of zone refining was, the greater the purityofspecimen became.
(2) The more the number of zone pass was, the greater the zone refining effect became.
(3) It was very difficult to eliminate Cu, Co and Ni from the reelectrolytic iron.
(4) The value of RRR min, was obtained in the magnetic field of 800-900 Oe.
(5) The value of RRR min was independent on the electric current in the range from 50 to 450m A.
(6) The non-deoxidated common specimen of the Iron and Steel Institute of Japanwas purifiedb y zone refining more than the deoxidated one was.
(7) It was effective to anneal the sample at 800° in wet hydrogen atmosphere after zoner efining.
(8) Specimen covered with calcium fluoride was refined by zone melting in wet hydrogen and RRR of its specimen was fairly good.
(9) The thermoelectromotive force could be used as one of the methods of the purity measurements when RRRmin was less than 200.