| 摘要 |
PURPOSE:To prevent a decrease of a copper ratio in case of drawing a wire and a disconnection, and to obtain a copper covered wire of a high copper ratio by raising an adhesive strength of a copper or copper alloy layer for covering a core wire of steel or a nickel alloy. CONSTITUTION:A copper plating layer of 1-30W% is provided on a core material 1 of steel or a nickel alloy, and also a covering layer 2 of copper or a copper alloy is provided on said layer. Subsequently, wire drawing is executed to >=30% reduction by a die of a low angle of 2-5 deg. half angle, annealing is executed for 30min or more at 600-900 deg.C in a reducing atmosphere containing hydrogen, and a copper covered composite wire of 80-90% total copper weight ratio is obtained. In this case, the reason why the reduction is limited is because an adhesive degree of the covered copper 2 and the core material 1 becomes worse in case of <=30%. Also, the reason why the reducing atmosphere containing hydrogen is used for annealing is because a reduction of an oxide for lowering the adhesive degree of copper and the core material and an invasion of oxygen are prevented, and also a washing degree of the surface of the composite wire is raised. Moreover, the reason why the annealing time is limited is because the adhesive degree drops in case of <=30min. Also, the reason why a low angle die is used is because the copper ratio is decreased and a disconnection is caused. Furthermore, the reason why the upper limit of the annealing temperature is set to 900 deg.C is because embrittlement of the surface copper layer is generated when exceeding 900 deg.C.
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