Dissolution of Iron in Molten Zinc in Continuous Sheet Galvanizing

Abstract

In continuous sheet galvanizing process, dissolution of iron into molten zinc results in a fairly great amount of dross. In order to decrease the harmful dross, the amounts of dissolved iron into galvani- zing bath have been measured in several conditions.
(1) According to our method studied here the iron loss by the reaction between molten zinc and solid iron is divided into two quantitative terms; a quantity dissolved and that in alloy layer.
(2) Under a condition which corresponds to the practical continuous sheet galvanizing process, the above mentioned quantities are both in the range of 0.1-0.5 g/m². For example, in the case of 10 seconds immersion in a 0.18% Al bath, quantity of dissolved iron is 0.39±0.09 g/m² and the quantity of iron in alloy layer is 0.24±0.10g/m2.
(3) The quantity of dissolved iron obtained here corresponds fairly well to the amount of drossformed in practical processes.
(4) The incubation period is 0.5-1 min or 5 min depending on the phase in alloy layer; the former corresponds to δ phase and the latter to Fe₂Al₅ phase.