Surface analysis of polysiloxane/metal oxide interfaces

The interfaces between various types of silane-based primers and abraded mild-steel surfaces have been investigated using two surface-specific techniques in an attempt to ascertain the bonding mechanism between primer and metal. The XPS technique gave semi-quantitative information about the relative concentrations of primer and exposed steel while the SSIMS technique enabled the chemical state of the first few monolayers of surface to be elucidated. From some primer/metal systems the presence of FeSiO⁺ radicals was detected by SSIMS and it was found that the environmental resistance of structural adhesive joints, employing the various silane-based primers, could be directly related to the presence or absence of this radical.