Organosilane modified Zr-based conversion layer on Zn-Al alloy coated steel sheets

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 was 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.