Zirconium based conversion layers are deliberated as environmentally friendly alternatives replacing classical trication phosphatation and chromate-based passivation layers in the automotive and coil-coating industry. Based on excellent electronic barrier properties they provide an effective corrosion protection of the metallic substrate. To investigate the influence of organofunctional silanes on the protection properties of these pre-treatment systems, 3-gylcidoxypropyltrimethoxysilane (γ-GPS) was added to the aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H2ZrF6). The surface composition of these modified conversion layers were determined using X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (FT-IRRAS) and confocal Raman microscopy (CRM). Scanning Kelvin Probe (SKP) measurements were obtained on organic coated samples in order to investigate the corrosive cathodic delamination process in
more detail.