Experimental Investigation of the Interphase in an Epoxy-Aluminum System

Abstract

The interphase in an epoxy-aluminum system has been revealed and characterized using scanning electron microscopy, ion etching, energy-dispersive x-ray analysis, and nano-indentation. The interphase was of irregular thickness, nominally between 2 and 6 μ, and corresponds to a region 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 effective elastic modulus (E/(1-v²)) that was 13% greater than that of the bulk resin, far from the aluminum. The interphase was also approximately 4% harder than the bulk adhesive.

Key Words:

• Interphase (thickness, modulus, structure)
• mechanical properties
• epoxy adhesive
• SEM
• ion etching
• EDX
• nano-indentation