| 摘要 |
PROBLEM TO BE SOLVED: To secure pitting corrosion resistance to an alkaline soln. and to make better the brazability to a fin by composing a sacrificial material laminated on one side of a core material made of an Al alloy of an Al alloy contg. specified amounts of Ni, Zn and Fe. SOLUTION: A heat exchanger is composed of a composite material obtd. by laminating a sacrificial material made of an Al alloy on one side of a core material made of an Al alloy. The compsn. of this sacrificial material is the one contg., by weight, >0.1 to <2.0% Ni >4.0 to <10.0% Zn >0.1 to <1.0% Fe, and the balance Al with inevitable impurities. Moreover, preferably, one or >= two kinds selected from >0.005 to <1.0% In, >0.005 to <1.0% Sn and >0.1 to <4.0% Mg are added thereto. Furthermore, a brazing filler metal composed of an Al alloy contg. a large amt. of Si and whose m.p. is lower than those of the core material and the sacrificial material is laminated on the other side of the core material according to need. By making the electric potential of the Al alloy of the sacrificial material remarkably baser than that of the core material, the extension of corrosion to the core material can be prevented. |
