The Effect of Additives (NH<sub>4</sub>Cl) to Elimination of the Iron Dissolved in Flux Solution of Hot Dip Galvanizing Process

Abstract

Hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other fields etc.. Recently, the cost of zinc is getting higher and higher, thus, a proper manufacturing process should be developed possibly to reduce the cost of production. one of hot dip galvanizing process, that is, flux solution immersion process is very important to control more effective coating. However, flux solution is deteriorated with increasing its using time because dissolved iron from structural steel due to continuous flux treatment was increasingly increased, which is resulted in coating badness and increment of dross. In this study, the effect of additives to elimination of iron dissolved in flux solution was investigated with four types of inner solution, that is, solution of inner barrel was filled with seawater, NaOH, thiourea, including parameters of amounts of NH4Cl(5,10,15 and 20g) and electrolysis experiment was carried out with applied current density at 20mA/cm2. For the best elimination effect of iron from flux solution, it is considered that inner barrel with separator should be filled with inner solution different from original flux solution which is involved in iron ion, and the inner solution should be composed with seawater added with additives such as NH4Cl(10g), NaOH(0.2 g) and thiourea(0.5g) when the applied current density by electrolysis method is 20mA/cm2.