HEAT EXCHANGER MADE OF ALUMINUM ALLOY

摘要

An aluminum alloy thermal exchanger is disclosed having a surface not containing any harmful chromium ions and having a good corrosion resistance and a good hydrophilicity. The aluminum alloy thermal exchanger has a first protective layer produced by using a treatment liquid containing substances (a) and (b) indicated below, and it further has a second protective film produced by applying a treatment liquid containing substances (c), (d), (e) and (f) indicated below, wherein the weight of zirconium in (f) is 40 to 350 % by weight of vanadium in (e), wherein (a) = water soluble vanadium compound (b) = fluorozirconium complex compound (c) = aqueous polyvinyl alcohol polymer having a vinyl alcohol unit of more than 40 mol % and an additional polymerization unit (other than the vinyl alcohol unit indicated above) of less than 60 mol % (d) = polyoxyethylene glycol with an average molecular weight of 6,000 to 1,000,000 (e) = vanadium compound (f) = zirconium compound.ar