Research For Flux Used In One-Step Hot-dipping Galfan Steel Wire And Study On Properties & Structure Of The Coating

The aim of the study is to find a new flux used in one-step hot-dipping Galfan (an eutectic zinc alloy containing 5% aluminum )coating on steel wire with flux process.The fluxes in the study include Organic matter, fluoride, chloride and electrodepositing layer . Imitating the industrial lines, the process in the lab and evaluation-criterion of the coating is established and orthodoxy experimental design method is adopted. There are two main kinds of flux researched in the dissertation, chemical flux and pre-electrodepositing layer flux. Experimental results show that a lot of defects, such as un-galvanized spots, holes, bubbles and particles, were found in the coating that manufactured with the pure chemical flux. While depositing zinc layer acquired, defects decreased, and the fluoride and chloride contribute to the decrease of un-galvanized spots and methyl alcohol contributes to the decrease of air holes and bubbles.Corrosion-resistance and binding force of the one-step Galfan hot-dipped wire are better than those of the Galvanized coated wire and duplex-step coated Galfan wire.Comparing to the traditional Galvanized process and duplex hot-dipped Galfan wire , the coating acquired by the new process had a thin Fe2Al5Znx transitional layer, which is less then 0.2 urn, and a duplex phase which consists of an approximately 8%(in weight) Al phase and a approximately 4%(in weight) Al phase were found. In the transitional zone, the content of Al is much higher then that in the other parts. The duplex phase and the enrichment of aluminum are the new possible reason for the excellent corrosion resistance. In the study the corrosion test also shows that the small holes do not do much harm to the corrosion resistance of the Galfan coating.