| 摘要 |
An aluminum alloy heat exchanger formed by assembling and brazing an aluminum alloy tube and an aluminum alloy fin to each other, wherein a coating for brazing comprising 1 to 5 g/m 2 of Si powder, 3 to 20 g/m 2 of Zn containing flux, and 0.2 to 8.3 g/m 2 of binder is formed on the surface of the aluminum alloy tube; the fin contains 0.8 to 2.0% by mass of Mn, Si in an amount of 1/2.5 to 1/3.5 of Mn content; less than 0.30% by mass of Fe, and Zn in an amount that is controlled in relation with the amount of the Zn containing flux in the coating for brazing to be in a region enclosed by points A, B, C, D, E, F of FIG. 5 ; a fillet comprising brazing filler of the coating for brazing is formed between the tube and the aluminum alloy fin after the brazing; a primary crystal portion that joins the fin and the tube is formed in the fillet; a eutectic crystal portion is formed in a portion other than the primary crystal portion; and an electric potential of the primary crystal portion is set equal to an electric potential of the aluminum alloy fin or higher than the electric potential of the aluminum alloy fin. |
