resumo
Hybrid organic-inorganic sol-gel-matrices, with up to 20 wt.% incorporated ceria nanoparticles, have been employed as coatings for an AA2024-T3 aluminium alloy. The morphology of the coatings and associated nanoparticles has been examined by conventional and high-resolution transmission electron microscopy, revealing a relatively uniform distribution of 5 nm size nanoparticles across the coating thickness. Electrochemical studies indicate a general beneficial effect of incorporation of ceria nanoparticles, although the performance of the coated alloy depends on the nanoparticle content. Electrochemical polarisation behaviour revealed that the coating decreased the anodic current density by about seven orders of magnitude compared with the uncoated alloy, with high breakdown potentials in chloride-containing solution. Accelerated salt spray testing showed that corrosion in an artificial scratch is blocked most efficiently by high ceria contents, whereas general corrosion is inhibited effectively with comparatively low ceria contents. Electrochemical impedance spectroscopy indicated degradation of the barrier properties of coatings with increased amounts of incorporated nanoparticles. Assessment of the abrasion and scratch resistance, and hydrophobicity also revealed additional beneficial functional properties of the coatings containing nanoparticles. (C) 2009 Elsevier Ltd. All rights reserved.
palavras-chave
CONVERSION COATINGS; CHROMATE; INHIBITION; MECHANISM; CERIUM; NANOPARTICLES; PERFORMANCE; ABILITY; COPPER; FILMS
categoria
Materials Science; Metallurgy & Metallurgical Engineering
autores
Schem, M; Schmidt, T; Gerwann, J; Wittmar, M; Veith, M; Thompson, GE; Molchan, IS; Hashimoto, T; Skeldon, P; Phani, AR; Santucci, S; Zheludkevich, ML
nossos autores
Mikhail Zheludkevich
Investigador Principal ConvidadoGrupos
agradecimentos
The authors acknowledge the support of the European Community for funding of the Research Project MULTI PROTECT 'Advanced Environmentally Friendly Multifunctional Corrosion Protection by Nanotechnology' (Contract No NMP3-CT-2005-011783).