Patent attributes
The present invention provides a heat exchanger which is assembled by brazing an aluminum fin material to the outer surface of an aluminum tube material formed by bending a sheet material, in particular, an aluminum heat exchanger which can be suitably used as an automotive heat exchanger such as a condenser or evaporator. The tube material is formed of a two-layer clad sheet which includes a core material and an Al—Zn alloy layer clad on the core material. The Al—Zn alloy layer is clad on the outer surface of the tube material and brazed to the aluminum fin material. The potential of the Al—Zn alloy layer in a normal corrosive solution is at least 100 mV lower than the potential of the core material in the normal corrosive solution. The potential of the Al—Zn alloy layer in the normal corrosive solution is lower than the potential of the core material in high-concentration corrosive water. The normal corrosive solution refers to an aqueous solution containing 10 g/l of NaCl and 0.3 g/l of Na2SO4, and the high-concentration corrosive water refers to an aqueous solution in which the NaCl concentration is increased by 30 times by concentrating the above aqueous solution.
