The reaction of water with abraded aluminum surfaces as studied by Fourier transform infrared spectroscopy (FTIR)

Studies of silane adsorption onto aluminum surfaces cleaned using wet chemistry techniques indicate that adsorption is very rapid, on the order of tens of seconds. In contrast, an empirical study of the performance of adhesive joints as a function of silane deposition conditions on grit-blasted aluminum surfaces, showed that the silane-containing solution needed to be left in contact with the surface for 10 to 20 min to obtain optimum performance. This time lag is believed to result from the time required to hydrolyze Al=O bonds on the surface. This hydrolysis process is shown to be much faster as the pH of the solution becomes more basic or acidic. At pH 5 or pH 9, the hydrolysis is complete in less than 1 min. (C) 1999 Elsevier Science B.V. All rights reserved.