Applications of Surface Analysis Techniques to Studies of Adhesion.

The question is often asked, which is the best surface chemistry tool for research on adhesive bonding This question is difficult to answer because it depends on the aspects of adhesion which is being studied. Often a combination of instruments must be used to take advantage of the strong points of each. In metal-to-metal bonding there are many facets of adhesiveadherend interaction. Elemental characterization of adherends, especially when composition with depth is desired, is often best accomplished with Auger Electron Spectroscopy AES. When information of chemical bonding is required, X-Ray Photoelectron Spectroscopy XPS is the choice of most workers. Extremely thin layers of material when first layer surface sensitivity is needed requires Ion Scattering Spectrometry ISS. The high sensitivity of Secondary Ion Mass Spectrometry SIMS to many elements important in adhesive bonding makes this technique useful, especially coupled with other methods, such as ISS and AES. Modern surface analysis along with Scanning Electron Microscopy SEM provides information on failure surfaces to allow unequivocal determination of the mode of failure. Problems such as charging and decomposition under the probing beam are encountered when characterizing the part of the failure surfaces containing the adhesive.