A Review on LDH-Smart Functionalization of Anodic Films of Mg Alloys

Abstract

This review presents an overview of the recent developments in the synthesis of layered double hydroxide (LDH) on the anodized films of Mg alloys prepared by either conventional anodizing or plasma electrolytic oxidation (PEO) and the applications of the formed composite ceramics as smart chloride traps in corrosive environments. In this work, the main fabrication approaches including co-precipitation, in situ hydrothermal, and an anion exchange reaction are outlined. The unique structure of LDH nanocontainers enables them to intercalate several corrosion inhibitors and release them when required under the action of corrosion-relevant triggers. The influences of different variables, such as type of cations, the concentration of salts, pH, and temperature, immersion time during the formation of LDH/anodic film composites, on the electrochemical response are also highlighted. The correlation between the dissolution rate of PEO coating and the growth rate of the LDH film was discussed. The challenges and future development strategies of LDH/anodic films are also highlighted in terms of industrial applications of these materials.

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…Consequently, Mg–Gd alloys shows better long-term degradation performance compared to anodized AZ31 Mg alloy. Since, anodic oxidation coatings singularly cannot full fill diverse clinical demands several studies reported their combination with chemical conversion [ 174 , 175 ], electrodeposition [ 176 ], LDHs [ 177 ], sol-gel [ 178 ] coating techniques. These coatings exhibit promising improvement in corrosion resistance and bioactivity of Mg alloys.…”

Chromate-Free Corrosion Protection Strategies for Magnesium Alloys—A Review: Part II—PEO and Anodizing

“…The first directly grown LDH on PEO of Mg alloys without autoclave was achieved by Petrova et al [ 290 ]. Currently, LDH post-treatment is being successfully exploited for the fabrication of composite PEO/inhibitor-loaded LDH coatings on Mg alloys in an increasing number of works [ 291 , 292 , 293 , 294 , 295 , 296 , 297 ]. Chen et al investigated PEO/LDH systems with a variety of cations in the LDH layer, such as Ni-LDH, Zn-LDH, Al-LDH, and MgFe-LDH [ 294 , 295 ], of which Ni-LDH was found to form a continuous LDH layer over the PEO surface and produce an order of magnitude increase in total impedance (up to 5 × 10 5 Ωcm 2 ) compared with a stand-alone PEO coating.…”

Recent Progress in Functionalized Coatings for Corrosion Protection of Magnesium Alloys—A Review

“…Micro arc oxidation (MAO) refers to a novel technology for in-situ growth of ceramic oxide film on an Mg alloy, and the formed MAO coating shows a rough microstructure and is firmed to Mg substrate [ 35 , 36 , 37 ]. MAO can significantly improve the corrosion resistance of Mg alloy substrates.…”