Tribocorrosion Properties of PEO Coatings Produced on AZ91 Magnesium Alloy with Silicate- or Phosphate-Based Electrolytes

In this work, the tribocorrosion behavior of plasma electrolytic oxidation (PEO)-coated AZ91 samples was studied. In particular, two different coatings were produced and compared. One was obtained with an alkaline electrolyte containing sodium phosphate, whereas the other one was produced with an al...

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Bibliographic Details
Published in:Coatings (Basel) 2018-06, Vol.8 (6), p.202
Main Authors: Pezzato, Luca, Vranescu, Dragos, Sinico, Marco, Gennari, Claudio, Settimi, Alessio, Pranovi, Pietro, Brunelli, Katya, Dabalà, Manuele
Format: Article
Language:English
Subjects:
Aluminum alloys
Corrosion resistance
Corrosive wear
Electrochemical impedance spectroscopy
Electrodes
Electrolytes
Engineering
Magnesium alloys
Magnesium base alloys
Oxidation
Pin on disk tests
Plasma
Protective coatings
Scars
Silicates
Sodium phosphate
Sodium silicates
Titanium alloys
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Summary:In this work, the tribocorrosion behavior of plasma electrolytic oxidation (PEO)-coated AZ91 samples was studied. In particular, two different coatings were produced and compared. One was obtained with an alkaline electrolyte containing sodium phosphate, whereas the other one was produced with an alkaline electrolyte containing sodium silicate. The coatings were characterized with SEM-EDS and XRD techniques, and after the tribocorrosion tests, the wear scars were analyzed with SEM-EDS. The tribocorrosion behavior was evaluated measuring the OCP during a pin on disk test performed in an aggressive environment. Moreover, potentiodynamic polarization and electrochemical impedance spectroscopy tests were performed, to evaluate the corrosion resistance of the different samples in the absence of wear phenomena. The behavior of all the PEO-treated specimens was compared with the one of the untreated sample. A remarkable increase in the tribocorrosion performances after the PEO treatments was observed. Moreover, the samples obtained with the electrolyte containing silicates showed higher tribocorrosion performances.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings8060202