Evaluation of the role of surface pretreatments on thecorrosion process. Correlation between conventional andelectrochemical tests

The influence on the anticorrosion properties of three different pretreatmentsapplied on steel panels, before being powder-paint coated, is investigated both byconventional tests (cross cut, impact resistance, and neutral salt spray tests) andelectrochemical tests (electrochemical impedance spectroscopy (EIS) andaccelerated cyclic electrochemical technique (ACET)). Amorphous phosphate,microcrystalline phosphate, and a sol-gel, based on 3-aminopropyltriethoxysilane(APTES), were the different pretreatments that were analyzed. All of them werecompared with a non-pretreated coated carbon steel panel. The microcrystallinephosphate, followed by the sol-gel surface treatments, showed the best systemproperties. These good results are attributed to PO34ions available at the interface,and to covalent bonds generated by the silicon network and the substrate surface,respectively