Development of the Flux Solution for Omission of Water Washing Treatment of Hot Dip Galvanizing Process

Abstract

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. In this study, one of hot dip galvanizing process, that is, omission of water washing treatment which is performed after acid cleaning was investigated with some types of flux solution which is added with additives such as acid cleaning solution, NH4OH, Al(OH)3 and H2O2. The decrement of pH by omission of water washing treatment could be recovered to its original value due to neutralization reaction with addition of NH4OH. The flux solution added with both NH4OH and Al(OH)3 exhibited nearly the same color and pH value as those of original flux solution with no added, and the galvanized sample by using this flux solution tended to show a relatively good corrosion resistance compared to other samples treated with different types of flux solution. Furthermore, the flux solution added with NH4OH, Al(OH)3 and H2O2 exhibited a different color as that of original flux solution, and sediments were observed, in addition, its sample exhibited a lower corrosion resistance. Consequently, it is suggested that simplification of process, so-called, omission of water washing treatment may be able to achieve with development of an optimum type of flux solution added with additives.