X‐ray photoelectron microscopy applied to metal/epoxy laminates Available to Purchase

In this article we describe the application of x‐ray photoelectron microscopy to an industrial epoxy laminate. Cold rolled steel and galvanized steel bonds of an epoxy/dicyandiamide adhesive were studied by lap‐shear strength measurements; the fracture surfaces of the sheared coupons were subsequently examined by x‐ray photoelectron microscopy and x‐ray photoelectron spectroscopy. X‐ray photoelectron microscopy allows one to identify the lateral distribution of chemical elements and to distinguish between particulates (silicate filler), adhesively failed regions, and bulk epoxy material with a resolution of 10 μm. Areas selected in the microscopy mode were then analyzed by x‐ray photoelectron spectroscopy to get information on the local interfacial composition. We find that a reaction between dicyandiamide and the zinc‐oxide surface leads to diffusion of molecular zinc complexes into the polymer matrix when the bonds are aged for 14 days in a saturated water vapor environment at 70 °C. No significant decrease in bond strength is induced by the aging process.