Reduction of Pb has become an urgent topic in discussions of ways to reduce the burden on the environment. The authors have been developing substitutive materials made of Pb-8wt% Sn coated steel sheets (which are known as Terne sheets) for automotive fuel tanks and chassis for home electrical appliances. Results have confirmed that Sn-Zn hot-dip coated steel sheets produced by a flux method can substitute for Terne sheets.
The Sn-Zn hot-dip coated layer has a lower potential than Fe due to the content of a small amount of Zn. The layer also displays sacrificial corrosion protection.
Zn crystal in the coated layer becomes coarse and Zn dissolves excessively when the Sn-Zn coated layer is over 11wt% Zn.
Accordingly, Sn-8wt% Zn is the most balanced composition for sheets used for inner and outer corrosion resistance in fuel tanks.
Results confirmed that Sn-Zn hot-dip coated steel sheets treated with special chemically treated film can confirm to various characteristics for fuel tanks. Subsequent use of lead for automotive parts may be reduced sharply.
