Characterisation and Electrochemical Evaluation of Plasma Electrolytic Oxidation Coatings on Magnesium with Plasma Enhanced Chemical Vapour Deposition Post-Treatments

• Published in: Plasma processes and polymers Vol. 13; no. 2; pp. 266 - 278
• Main Authors: Sun, Ming, Yerokhin, Aleksey, Matthews, Allan, Thomas, Michael, Laukart, Artur, von Hausen, Margret, Klages, Claus-Peter
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.02.2016; Wiley Subscription Services, Inc
• Subjects: Chemical vapor deposition; Coatings; corrosion; Corrosion resistance; electrochemical measurements; Magnesium; Oxidation; Plasma; plasma electrolytic oxidation; Plasma enhanced chemical vapor deposition; plasma-enhanced chemical vapour deposition; post-treatment; Precursors; Protective coatings
• ISSN: 1612-8850; 1612-8869
• DOI: 10.1002/ppap.201500059

Plasma enhanced chemical vapour deposition (PECVD) post‐treatment with three different precursors is employed to improve corrosion resistance of plasma electrolytic oxidation (PEO) coated Mg. Surface morphology, chemical and phase composition are characterised by SEM, EDS, and XRD analyses, whereas corrosion resistance is assessed by electrochemical tests. PECVD post‐treatments can significantly affect PEO coatings, resulting in sealed pores and multi‐layered inner barrier structure. Depending on the precursor, this can have both positive and negative influence on the corrosion resistance of the PEO coatings. The PECVD post‐treatment with hexamethyldisiloxane precursor significantly improves corrosion resistance of PEO coatings, providing the best corrosion protection of Mg. A series of studies were carried out to investigate the duplex coatings produced by a sequential plasma electrolytic oxidation (PEO) and plasma‐enhanced chemical vapour deposition (PECVD) processes. The results offer a new strategy for plasma‐assisted surface treatments of Mg to produce duplex oxide coatings with enhanced corrosion resistance.