Aluminium heat exchanger excellent in corrosion resistance

摘要

A heat exchanger which is assembled by brazing an aluminum fin material (1) to the outer surface (3) of an aluminum tube material (2) 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 (4) and an Al-Zn alloy layer clad (3) on the core material (4). 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 normal corrosive solution is 100 mV or more 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 Na 2 SO 4 , 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.