Carboxylic acids are found to adsorb weakly to the native oxide surface of aluminum. Under heat exchange conditions, synergistic carboxylate combinations provide superior high-temperature aluminum corrosion protection and show excellent heat-transfer characteristics. The surface films formed under these dynamic heat-transfer conditions are characterized with the use of X-ray photoelectron spectroscopy (XPS). Fourier transform infrared (FT-IR) is also used for the study and characterization of the surface films formed. The results are compared with the FT-IR data of the pure Al-carboxylate complexes. The combination of these results reveals that, under heat transfer conditions, carboxylates are chemically bonded to the aluminum surface. This molecular film shows excellent inhibition properties for aluminum.
F. Verpoort, T. Haemers, P. Roose, and J.-P. Maes, "Characterization of a Surface Coating Formed from Carboxylic Acid-Based Coolants," Appl. Spectrosc. 53, 1528-1534 (1999)