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AssigneeSumitomo Metal Industries, Ltd.
InventorsToshio Nakamori, Masashi Yamamoto, Tamotsu Toki, Hirohito Masumoto, Mutsuo Sagara, Hiroo Maeda
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A batchwise hot dip plating method is performed by dipping a metallic material in a molten metal plating bath, following fluxing by dipping the metallic material in a bath of a fused salt flux (e.g., a mixture of cryolite and one or more alkali metal chlorides and optionally aluminum fluoride) having a melting temperature at least 5.degree. C. higher than the temperature of the molten metal plating bath, which also serves to preheat the metallic material. In the case of hot dip plating with an Al--Zn alloy, particularly a Zn/55% Al/0.5-2% Si alloy, a bare spot-free plated coating having good appearance can be formed by a reduced duration of dipping in the plating bath without post-plating treatment to remove flux residues. The use of a plating tank having a cross section of a round shape such as a semicircular shape or an oblong semielliptic shape, rather than a rectangular box shape, brings about a significantly extended service life of the plating tank.
A method for hot dip plating of a metallic material comprising, prior to plating, dipping a metallic material to be plated in a bath of a fused salt flux, and then dipping the metallic material in a molten metal plating bath to perform hot dip plating thereon, wherein the fused salt flux has a melting temperature at least 5.degree. C. higher than the temperature of the molten metal plating bath.
Dependencies are inferred from the claim text.