| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coated tube superior in brazing properties and corrosion resistance by making a base metal surface of aluminium alloy tube, outer surface of which is coated with brazing filler alloy by spraying, hasa roughness in depth of specified dimension or more and making a difference between the highest protrusion on the base metal surface and the highest protrusion of the brazing filler layer coated on it is within a specified dimensional range. SOLUTION: Brazing filler alloy is sprayed to the outer surface of aluminium alloy tube manufactured through extrusion. As the brazing method, high-speed flame brazing is preferable. The tube base metal surface has roughness of 10μm or more in depth, and the difference between the highest protrusion par 21b on the base metal surface and the highest protrusion part 22a of the brazing filler layer coated on it is made 3 to 25μm. Before brazing is cone, the fin contacts the tube at the portion of 21b, but when brazed, it contacts the tube at the portion 22a, and so dimensional difference before and after brazing is reduced, making it possible to prevent occurrence of locally non- coated portions.
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