|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1992 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1991 : ¥1,400,000 (Direct Cost : ¥1,400,000)
First,the compositions of the sulfate and chloride baths used in this research were determined from the information in the literature on the production of electrolytic Fe. On the basis of the thermodynamic properties of the impurities which might be found to include in the electrolytic Fe,the thirty kinds of impurities were classified into the four groups as follows;(1)elements which are more noble than Fe and can be electrocodeposited with Fe,(2)elements which are less noble than Fe and can be electrocodeposited from aqueous solutions,(3)elements which cannot be electrodeposited from aqueous solutions and (4) Gaseous elements.Based on this classification,the mechanism of impurity inclusion into electrolytic Fe was estimated.
Then,the electrodeposition of Fe from the baths containing the impurities which were capable of being electrodeposited from aqueous solutions was carried out to clarify the inclusion mechanism of the impurities.As for Cu and Cd,the normal codeposition behavior was observed and the content of these elements did not lowered below the metal-percentage of these impurity ions in bath.
Ni and Co,which were more noble than Fe,showed anomalous codeposition behavior in sulfate solutions in which the contents of Ni and Co of the deposited Fe were lower than the impurity level in baths.On the other hand,the impurity contents of Fe deposited from chloride solutions was higher than that from sulfate solutions because of the suppression of this anomaly.
Further,it was found that the content of Pb,Sn and Mo contents of the deposit were lower than the impurity level in the baths due to their chemical and electrochemical properties of these elements.
On the other hand,not only the considerable polarization during the electroreduction of more noble Fe but also the underpotential deposition of Zn caused the significant codeposition of Zn with Fe and electrolytic inclusion of Zn must be taken into consideration.