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

Studies of silane adsorption onto aluminum surfaces cleaned using wet chemi stry techniques indicate that adsorption is very rapid, on the order of ten s of seconds. In contrast, an empirical study of the performance of adhesiv e joints as a function of silane deposition conditions on grit-blasted alum inum 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 A l=O bonds on the surface. This hydrolysis process is shown to be much faste r 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.