Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
Research Paper
Passivation Behavior of Iron in Concentrated LiBr Solutions Containing Molybdate and Nitrate at Elevated Temperature
Hitoshi YashiroMasaru KawataMasahiko ItohKenji MachizawaKen-ichi Shimizu
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2006 Volume 55 Issue 12 Pages 549-553

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Abstract

Since the control of corrosion by the addition of inhibitors is one of the key technologies for the adsorption refrigeration systems, the passivation behavior of an iron electrode in the 17.3 mol/kg LiBr+0.1 mol/kg LiOH solution containing molybdate and nitrate has been investigated at 428 K through electrochemical measurements and film analysis by radio frequency grow discharge optical emission spectroscopy (rf-GDOES). The results indicated that molybdate worked as a principal inhibitor in the system; molybdate was able to passivate iron without causing any pitting. However, the oxidizing power of molybdate was not sufficient to form a passive film on iron rapidly enough. The process could be assisted by the addition of nitrate; iron was passivated very quickly when the solution contained both molybdate and nitrate. Cares should be paid to that nitrate of higher concentrations could cause pitting especially when the concentration of molybdate was relatively low. The oxide films formed on iron in the presence of molybdate and nitrate were much thinner than those formed with only molybdate.

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© 2006 Japan Society of Corrosion Engineering
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