| 摘要 |
PURPOSE:To obtain a die casting Zn alloy for a wristwatch case having high hardness, excellent polishability and free-cutting ability, by specifying the compsn. consisting of Cu, Al, Sb and the balance Zn. CONSTITUTION:The die casting Zn alloy having the high hardness, excellent polishability and free-cutting ability is obtd. by constituting said alloy from 0.2-1.0wt% Cu, 10-15% Al, 0.2-1.0% Sb and the balance Zn. Said Zn alloy is obtd. by fusing Cu together with Al at the specific comps. ratio in a graphite crucible at about 1,000 deg.C, injecting flux for the zinc alloy into said crucible, then admitting therein Zn and Sb fused together in another graphite crucible at about 500 deg.C to fuse together. The resulted Zn alloy has about 150-170 Vickers hardness and the inferiority of a percussion scar is hard to produce. The sagging and deformation of the shape are prevented at the time of polishing the watch case and the free-cutting ability is as well good, by which the accuracy of a finished surface can be improved.
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