Surface Characterization and its Rôle in Adhesion Science and Technology

Abstract

This chapter reviews a variety of methods of surface characterization that have been found to be useful in the study of adhesion. The methods considered can be conveniently classified in three groups: those that provide information regarding surface topography (scanning electron microscopy and atomic force microscopy [AFM]); those that probe the surface-free energy of a material (measurement of contact angles and inverse gas chromatography, in addition to simple test methods such as the water break test and dyne inks); and those that provide a surface-specific chemical analysis (X-ray photoelectron spectroscopy, Auger electron spectroscopy, and time-of-flight secondary ion mass spectrometry). All provide surface-specific information and this is essential for adhesion investigations as the forces responsible for adhesion operate over very short length scales and for any analysis to be meaningful the analysis technique must probe depths of a similar order of magnitude. These methods are used in all types of adhesion investigations, which, in general, can be considered in one of three areas of endeavor. The analysis of the unbonded surface and the relationship of surface characteristics to performance such as strength or durability, the forensic analysis of failed joints with a view to defining the exact locus of failure and any interfacial phenomena that may have exacerbated failure, fundamental studies of adhesion carried out with a view to gaining a fuller understanding of the interfacial chemistry of adhesion.