| 摘要 |
PURPOSE:To improve the corrosion resistance, especially the pinhole corrosion resistance of the title exchanger by a method wherein a pipe, which becomes the flow passageway of operating fluid, and a fin, consisting of brazing sheet provided with Al-Si series brazing alloy containing the specified rate of Zn, are brazed by a brazing means employing flux. CONSTITUTION:When Zn is contained in Al-Si series brazing alloy provided on the surface of a brazing sheet or a fin, the Zn or Al-Zn alloy is deposited on the surface of the sheet by a reaction between Zn and a flux while the film of the deposited Zn or Al-Zn alloy improves remarkably the corrosion resistance of a tube which becomes the passageway of operating fluid. The amount of Zn contained in the Al-Si series brazing alloy is about 1.3wt% or more because the improvement of the corrosion resistance is insufficient and the effect of the improvement of pinhole corrosion resistance is too small in case the content of Zn is too small. On the other hand, chloride such as NaCl, KCl, LiCl, ZnCl2 or the like, the floride of KF, AlF3, K3AlF6, ZnF2 or the like, for example, or the mixture thereof is employed as the flux.
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