Development of Quantitative Tools for the Assessment of Bond Surface Preparation Quality

摘要

Grit blasting produced excellent substrates for adhesive bonding, as predicted by both the wettability measurements as well as the work of adhesion calculations. The air plasma process created a highly wettable surface with very poor adhesive properties. Although the W_a was very similar for the grit blasting processes and the plasma process, much better adhesion was obtained using grit blasting process. As no attempt was made prior to joint fabrication to optimize the plasma treatment process, these results were not unexpected. Plasma and corona treatments are in general capable of providing excellent adhesion but must be developed for each application. Both under and over treatment can create a wettable but physically weak surface. For example, an underly aggressive process can leave a layer of oxidized contaminant species that are highly wettable but incapable of providing a strong interface. Likewise, an overly aggressive treatment will create low MW species through chain scission that are also highly wettable yet weak. This process is currently under investigation; preliminary results suggest that the current treatment conditions are much too aggressive.