Electrochemical Assessment of the Self-Healing Properties of Cerium Doped Sol-Gel Coatings on 304L Stainless Steel Substrates

摘要

The present work aims at assessing the corrosion behavior of 304L stainless steel substrates pre-treatedwith 3-glicidoxypropyltrimethoxy silane (GPTMS) solutions modified with cerium nitrate or ceriumoxide nanoparticles. Furthermore, the work aims at evaluating the self-healing properties of the dopantin intact and artificially scratched silane films via natural salt spray tests, electrochemical impedancespectroscopy (EIS) and d.c. potentiodynamic polarization. The morphological features of the coatedsubstrates were evaluated by atomic force microscopy (AFM) and optical microscopy. The resultsconfirmed the formation of transparent cerium modified sol-gel films without any defect and cracksand revealed the formation of a comparatively smooth nanostructure surface with a small heterogeneityin coating thickness in the sol-gel coatings modified with Ce(NO3)3.6H2O. Corrosion tests indicatedthat the CeO2 nanoparticles have good corrosion inhibition properties on scratched surfaces due totheir ability to complex other species, therefore contributing for the stabilization of the passive film. Inthis way, these particles display an anodic inhibition mechanism. It was found that the positive impact,both in the barrier properties and corrosion inhibition, was significantly improved by modifying thesilane solution with cerium nitrate. Presence of cerium nitrate, reinforces the barrier properties of thesilane films, reducing the corrosion activity and self-healing the corroded areas.