| 摘要 |
PURPOSE:To improve the corrosion resistance of an apparatus for which Al alloy members are used by quickly cooling the Al alloy members at a specific cooling rate from the supersaturation high temp. after brazing to prevent precipitation of an intermetallic compd. having the corrosion potential baser than the corrosion potential of Al. CONSTITUTION:An extruded and perforated tube 1 consisting of an Al alloy is bent zigzag and fin materials 2 coated with a brazing filler metal made of the Al alloy are mounted thereto to form a core for a heat exchanger made of aluminum. Such core is then heated for a prescribed time at a required temp. (610 deg.C, etc.) in a vacuum brazing furnace by which the core is subjected to brazing. The core is thereafter quickly cooled from the supersaturation high temp. to obviate the generation of the precipitation after the brazing down to an ordinary temp. at l10 deg.C/min cooling rate. The formation of the intermetallic compd. Mg2Al3, etc., having the corrosion potential baser than the corrosion potential of Al in the joined parts is prevented by the above- mentioned method. The acceleration of the corrosion in the joined part is, therefore, stopped and the corrosion resistance is improved.
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