Unconventional fluoride conversion coating preparation and characterization

0481439 - ÚFM 2018 RIV US eng J - Journal Article
Drábiková, J. - Fintová, Stanislava - Tkacz, J. - Doležal, P. - Wasserbauer, J.
Unconventional fluoride conversion coating preparation and characterization.
Anti-Corrosion Methods and Materials. Roč. 64, č. 6 (2017), s. 613-619. ISSN 0003-5599. E-ISSN 1758-4221
Institutional support: RVO:68081723
Keywords : fluoride conversion coating * magnesium * corrosion
OECD category: Coating and films
Impact factor: 0.460, year: 2017
http://www.emeraldinsight.com/doi/abs/10.1108/ACMM-02-2017-1757

The purpose of this paper is to compare electrochemical corrosion characteristics of conventional and unconventional fluoride conversion coating prepared on magnesium alloy. The chemical reaction of AZ61 with 38 wt. % hydrofluoric acid (HF) for 24 h was used as a conventional way of fluoride conversion coating preparation. The unconventionally prepared coating was created in Na[BF4] salt melt at 450 °C for 2 h. Morphology and chemical composition of prepared fluoride conversion coatings were studied with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Electrochemical corrosion characteristics of the coatings were analyzed in Hank's solution using potentiodynamic tests. Both the coating preparation ways resulted in a creation of uniform conversion coatings with the same thickness (1.3 ± 0.1 um). Some defects were observed on the coatings surface, however, the defects did not reach the AZ61 surface. Electrochemical tests performed in Hank's solution at 37 °C showed an improvement of corrosion resistance of AZ61 treated with fluoride conversion coatings when compared to the untreated material. Unconventionally prepared coating reached better electrochemical corrosion characteristics when compared to the conventionally prepared coating.
Permanent Link: http://hdl.handle.net/11104/0278861