Adhesion Measurement: Recent Progress, Unsolved Problems, and Prospects

In this paper, the term “basic adhesion” is used to signify the summation of all interfacial intermolecular interactions, whereas the term “practical adhesion” is used to represent the forces or the work required for the disruption—either at the interface or in the interfacial region—of the adhering system. There are many factors which influence practical adhesion, and these are discussed in detail. The relationship between practical adhesion and basic adhesion is discussed. Basic adhesion cannot be determined by the commonly used techniques for measuring practical adhesion. The virtues of an ideal practical adhesion test are outlined. Some of the techniques for adhesion measurement of thin films, thick films, and coatings are discussed briefly, and references are made to the recent reviews on this topic.

For a given adhering system, different techniques yield different practical adhesion values. The difficulties involved in adhesion measurement are highlighted, and the unresolved problems are brought into sharper focus.

The failure surfaces should be examined using surface analytical tools to ascertain the locus of failure, which is important in understanding the mechanism of failure.