Plasma electrolytic fluorination on Mg alloys: coating growth and plasma discharge behaviour. (2nd November 2021)

• Record Type: Journal Article
• Authors: Qi, Yuming; Peng, Zhenjun; Liang, Jun; Wang, Peng
• Is Part Of: Surface engineering. Volume 37:Number 11(2021)
• Page Start: 1373
• Page End: 1387
• Publication Date: 2021-11-02
• Subjects: Plasma electrolytic fluorination -- mechanism -- discharge behaviour -- coating growth -- AZ91 magnesium alloy -- plasma electrolytic oxidation -- non-aqueous electrolyte -- optical emission spectroscopy; Surfaces (Technology) -- Periodicals; Coatings -- Periodicals; 620.4405
• DOI: 10.1080/02670844.2021.1999078
• Languages: English
• ISSNs: 0267-0844

Abstract

ABSTRACT: In this work, plasma electrolytic fluorination (PEF) was performed on AZ91 alloy in a non-aqueous NH4 F-ethylene glycol (EG) electrolyte. The coating growth and the plasma discharge behaviour were investigated to understand the mechanism of PEF process. Results illustrated that the non-aqueous electrolyte determined the intrinsic characteristics of the PEF process, which resulted in the coating growth characteristics and plasma discharge behaviour distinct from those of a conventional PEO process. MgF2 compound formed from the combination of the oppositely charged ions Mg 2+ from the substrate and F- form the electrolyte. The deposition of MgF2 facilitated the growth of the PEF coating with an inward-growth characteristic. The discharge was characterised by a very small size and a weak intensity of the sparks, with an electron temperature (Te ) range of 3400∼3600 K. The three-type discharge model of conventional PEO processes was introduced to understand the mechanism of the PEF process.