Use of synergistic mixture of chelating agents for in situ LDH growth on the surface of PEO-treated AZ91

abstract

The principal possibility to grow layered double hydroxide (LDH) at ambient pressure on plasma electrolytic oxidation (PEO) treated magnesium alloy AZ91 in the presence of chelating agents is demonstrated for the first time. It avoids hydrothermal autoclave conditions, which strongly limit wide industrial application of such coating systems, and the presence of carbonate ions in the electrolyte, which lead to the formation of passive non-functionalizable LDH. A combination of chelating agents (sodium diethylenetriamine-pentaacetate (DTPA) and salicylate) were introduced to the treatment solution. The role of each additive and the influence of treatment bath composition on the LDH formation processes are discussed. A synergistic effect of DTPA and salicylate during LDH formation is discovered and its possible explanation is proposed.

keywords

PLASMA ELECTROLYTIC OXIDATION; LAYERED DOUBLE HYDROXIDE; HYDROTALCITE CONVERSION FILM; ACTIVE CORROSION PROTECTION; AZ31 MAGNESIUM ALLOY; MICRO-ARC OXIDATION; COATINGS; RESISTANCE; ALUMINUM; MICROSTRUCTURE

subject category

Science & Technology - Other Topics

authors

Petrova, E; Serdechnova, M; Shulha, T; Lamaka, SV; Wieland, DCF; Karlova, P; Blawert, C; Starykevich, M; Zheludkevich, ML

Groups

acknowledgements

This work was partially financed by the European project FUNCOAT (Horizon2020-MSCA-RISE-2018, grant agreement No. 823942). M.Se. and C.B. additionally would like to thank ACTICOAT project (Era.Net RUS Plus Call 2017, Project 477) for the financial support, while E.P. would like to acknowledge the financial support of the European project MULTISURF (Horizon2020-MSCA-RISE-2014, grant agreement No. 645676). The authors thank Anton Davydok for support at the beamline. We also thank PETRA III for granting the P03 proposal I-20190157.

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