Surface analysis

Techniques of physical and chemical analysis are described for studying the characteristics of surface treatments for adhesive bonding. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have the respective advantages of high resolution and excellent depth of field. Ion scattering spectrometry (IES), secondary ion mass spectrometry (SIMS), Auger electron spectrometry (AES), and X-ray photoelectron spectroscopy (XPS) are described along with such techniques as the FPL (Forest Products Laboratory) etch, phosphoric acid anodize, and plastic replica. Scanning electron micrographs are shown at various magnifications to show surfaces and bond failures. In one case, on the metallic side of a failure, the bent specimen showed a thin oxide layer (confirmed by Auger analysis) about 500 angstroms thick rather than 3000 to 4000 angstroms; the failure was attributed to improper surface treatment through loss of contact during anodizing or leaving the part in the phosphoric acid anodize long after the anodizing current was turned off.