Title: Electrochemical comparison between corrosion resistance of some thermally sprayed coatings

Authors: G. Bolelli, V. Cannillo, R. Giovanardi, L. Lusvarghi

Addresses: Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy

Abstract: Electrochemical polarisation and impedance spectroscopy tests in 0.1 M HCl and 0.1 M H₂SO₄ solutions were performed on HVOF-sprayed cermet coatings (WC-17% Co, WC-10% Co–4% Cr) and Atmospheric Plasma-Sprayed (APS) ceramics (Al₂O₃, Al₂O₂–13 wt%TiO₂, Cr₂O₃) with APS bond coat (Ni-Co-Cr-Al-Y). Reference tests were also performed on hard chrome electroplating. Plasma-sprayed coatings offer limited substrate protection owing to interconnected porosity, although the bond coat promotes some forms of passivation in H₂SO₄ HVOF-sprayed cermets possess good corrosion resistance in both environments. Chrome electroplating shows comparatively better corrosion resistance in H₂SO₄, but worse in HCl.

Keywords: impedance spectroscopy; electroplating; plasma spraying; HVOF; high velocity oxygen fuel; electrochemical polarisation tests; corrosion resistance; cermet coatings; ceramics.

DOI: 10.1504/IJSURFSE.2008.020495

International Journal of Surface Science and Engineering, 2008 Vol.2 No.3/4, pp.222 - 239

Published online: 27 Sep 2008 *

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