ALUMINUM HEAT EXCHANGER

PURPOSE:To prevent a fact that Mg in a core material reacts with a fluoride compound flux and a brazing failure is generated by forming a brazing sheet by a clad material of four layers consisting of a core material of an Al-Mg compound alloy, an Al-Si compound, a brazing filler metal, a diffusion preventive layer of a specific composition between both the materials, and a sacrifice anode layer of an Al-Zn compound. CONSTITUTION:A tube 1 is a brazing sheet consisting of a clad material formed by laminating successively a brazing filler metal 11, a diffusion preventive layer 12, a core material 13 and a sacrifice anode layer 14. Also, the diffusion preventive layer contains 0.2-2.0% Mn (weight ratio, the same hereinafter) and 0.05-0.35% Zr, and the remaining part consists of Al and impurities. Since the diffusion preventive layer is interposed between the core material 13 and the brazing filler metal 11, it does not occur that the flux of a fluoride compound and Mg in the core material 13 are brought into contact with each other at the time of brazing. Therefore, it does not occur that Mg in the core material 13 reacts with the flux and a brazing failure is generated.