Oxide films at metal surfaces

All metals, with the exceptions of the very noble ones, form oxide films on their surfaces on exposure to the atmosphere, and the compasitions of the.se surface oxides are of critical importance to the adhesion scientist. In some cases it is po.ssible to draw pandlels between the outcomes of exposures in UHV clean conditions and ambient oxidation this is certainly true for pure iron exposed to water vapor in UHV 171. which results in the formation of an FeOOH surface layer. Mild steel responds in the same manner, when cleaned by an abrasion process and passivated by air exposure. The early literature on the composition 

In general, it is now regarded as a requirement of any investigation of adhesion that the adherend surfaces are fully characterized by surface analysis before any adhesion tests are undertaken. This does, of course, beg the question concerning the inevitable hydrocarbon contamination. Such contamination will always be present in the spectrum recorded prior to bonding, the general opin- 

Although chemical analysis of the substrate is now a straightforward matter, recent research has concentrated on the extension of such analyses to other properties such as surface polarity and acido-basic characteristics. These are extremely important and may point the way to a predictive approach to bond integrity. They are discussed below in Section 5. 

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