| 摘要 |
PROBLEM TO BE SOLVED: To impart the anticorrosion performance of Zn to the inside surface of a container without contamination of a furnace by evaporated Zn, in vacuum-soldering a heat exchanger.SOLUTION: In a container 10 having an opening 12 communicating with a working fluid passage 11, at least the inner surface side is composed of aluminum of a Zn concentration of 0.05 mass% or lower, and the container 10 is temporarily assembled in such a state that a fin 30 composed of aluminum of a Zn concentration of 0.5-2.5 mass% is inserted and subjected to vacuum soldering to join the edge of the container 10 other than the opening 12 and to join the fin 30 with the inner surface of the container 10. Zn is evaporated from the fin 30 by heating in soldering so as to decrease the Zn concentration in the central part in the plate thickness direction of the fin 30 after soldering down to 0.4 mass% or lower. A concentration gradient in which the Zn concentration decreases from the central part to the front surface side is produced, and the Zn evaporated from the fin 30 is caused to adhere to the inner surface of the container 10 and also diffuse in the plate thickness deep part direction of the container 10 to form a Zn diffusion layer. |
