| 摘要 |
PROBLEM TO BE SOLVED: To extend the service life of an aluminum-made heat exchanger by generating an aluminum alloy layer having higher electric potential than that of the base material of an extruded flat tube and lower m.p. than that of the base material on the surface of the aluminum alloy-made extruded flat tube and brazing the extruded flat tube and the aluminum alloy-made fins with one another. SOLUTION: On the surface of the aluminum alloy-made extruded flat tube 4, mixture of brazing filler metal powder of Al-Si, Al-Cu or Al-Si-Cu, or of copper and/or silicon having a m.p. of the eutectic point with the aluminum lower than that of the aluminum alloy-made extruded flat tube 4, and flux powder and binder, is applied and also, they are heated to the m.p. of the brazing filler metal or a temp. higher than the eutectic point, and the brazing filler metal alloying layer 6 having higher electric potential than that of the aluminum alloy-made extruded flat tube 4 is generated on the surface of the aluminum alloy-made extruded flat tube 4 by alloying between the mixture and the base material and brazed with the aluminum-made fins 5. |
