THE INTERPHASE IN PAINTED METALS PRETREATED BY FUNCTIONAL SILANES

A new post-rinse treatment was developed to replace the standard chromate post-rinse treatment on phosphated metal substrates, The silicate/silane (SSL) treatment modifies the paint-phosphate interface to give improved adhesion and corrosion performance. Time-of-flight secondary ion mass spectrometry (TOFSIMS) was used to study the orientation of the silane. The orientation was critical for the final adhesion performance. Electrochemical impedance spectroscopy (EIS), an ideal technique for studying interfaces nondestructively, showed that the SSL treatment was effective in reducing the corrosion significantly. Mechanisms of adhesion and corrosion are described.