Anti-corrosion treatment method for aluminum heat exchanger
Disclosed is an anti-corrosion treatment method for a heat exchanger, in which even if an aluminum material-made heat exchanger having been flux-brazed by the NB process, in particular, an aluminum material-made heat exchanger to be used for automobile air conditioner is not subjected to a chemical conversion treatment in advance, not only corrosion resistance can be significantly enhanced without impairing hydrophilicity, but deodorizing properties can be enhanced. The anti-corrosion treatment method for an aluminum material-made heat exchanger includes bringing an aluminum material-made heat exchanger having been flux-brazed by the NOCOLOK brazing process into contact with a hydrophilic treatment liquid and then applying a baking treatment, thereby forming a hydrophilic film on the surface of the aluminum material-made heat exchanger, wherein the hydrophilic treatment liquid contains a hydrophilic resin and a lithium ion, and a lithium concentration in the hydrophilic film is from 0.05 to 25% by mass.
1. An anti-corrosion treatment method for an aluminum material-made heat exchanger comprising subjecting an aluminum material-made heat exchanger having been flux-brazed by the NOCOLOK brazing process to hydrophilic treatment liquid and then applying a baking treatment to form a hydrophilic film on the surface of the aluminum material-made heat exchanger, wherein
the hydrophilic treatment liquid contains a hydrophilic resin and a lithium ion, and a lithium concentration in the hydrophilic film is from 0.05 to 25% by mass; and
an ion exchange reaction occurs between an alkali metal ion in the flux and a lithium ion from the hydrophilic film, the reaction forming a sparingly soluble film at least at an interface between the flux and the hydrophilic film.
2. The anti-corrosion treatment method for an aluminum material-made heat exchanger according to claim 1 , wherein a film amount of the hydrophilic film is from 0.1 to 5.0 g/m 2 .
3. The anti-corrosion treatment method for an aluminum material-made heat exchanger according to claim 1 , wherein after subjecting the heat exchanger to a chemical conversion treatment in advance, the heat exchanger is brought into contact with the hydrophilic treatment liquid and then subjected to a baking treatment.
4. The anti-corrosion treatment method for an aluminum material-made heat exchanger according to claim 1 , wherein the heat exchanger is an aluminum material-made heat exchanger which has not been subjected to a chemical conversion treatment in advance.
5. The anti-corrosion treatment method for an aluminum material-made heat exchanger according claim 1 , wherein the hydrophilic resin is polyvinyl alcohol having a degree of saponification of 90% or more and/or modified polyvinyl alcohol.
6. The anti-corrosion treatment method for an aluminum material-made heat exchanger according to claim 1 , wherein the hydrophilic treatment liquid further contains a crosslinking agent.