| 摘要 |
PROBLEM TO BE SOLVED: To appropriately use for a filter for a highly corrosive liquid or a filler for glass lining of porcelain enamel or the like. SOLUTION: One precious metal wire selected from a platinum group metal, gold or silver as a core metal is inserted into a tubular body of copper, nickel, a copper alloy or a nickel alloy, is passed through a die to be drawn at plural times, after being drawn, the obtained plural wires of a fine dual structure are inserted into a tubular body of the same material as that of the previous tubular body and the drawings are conducted plural times through the die. These insertions/drawings are repeated until the precious metal wire cross section of the core metal is reduced to an area of <=50μm<2> to >=0.005μm<2> and then, the tubular metal is melted/removed. For reducing the hardness of the both metals during the period, heat treatment is conducted at least one time after the second insertion of the tubular body and thereafter.
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