EXPERIMENTAL INVESTIGATION OF THE INTERPHASE IN AN EPOXY-ALUMINUM SYSTEM

The interphase in an epoxy-aluminum system has been revealed and chara cterized using scanning electron microscopy, ion etching, energy-dispe rsive x-ray analysis, and nanoindentation. The interphase was of irreg ular thickness, nominally between 2 and 6 mu m, and corresponds to a r egion of greater resistance to ion etching and a marked absence of the silica particles used in the epoxy adhesive. Nano-indentation tests, traversing various sections of the interphase from the aluminum to the bulk resin, showed that the interphase region had, on average, an eff ective elastic modulus (E/(1-v(2))) that was 13% greater than that of the bulk resin, far from the aluminum. The interphase was also approxi mately 4% harder than the bulk adhesive.