Low temperature UV assisted sol-gel preparation of ZrO2 pore-sealing films on micro-arc oxidized magnesium alloy AZ91D and their electrochemical corrosion behaviors

Li, Na; Chen, Yuanqing; Deng, Bo; Yue, Jianshe; Qu, Wenwen; Yang, Hanxiao; He, Yuhang; Xia, Weimin; Li, Lingwei

doi:10.1016/j.jallcom.2019.04.124

Cited by 27 publications

(13 citation statements)

References 37 publications

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“…The electrical equivalent circuits (EECs) in Figure 5 were employed to fit the EIS spectra. For the purpose of obtaining accurate results, the capacitive responses were fitted by the constant phase elements (CPE), Q, whose impedance is defined as: (1) in which Y0 is the CPE constant, j = √ − 1, f is the frequency (Hz), n = α/(π/2) and α is the phase angle of the CPE (radians). The electrical equivalent circuits (EECs) in Figure 5 were employed to fit the EIS spectra.…”

Section: Eis Measurementmentioning

confidence: 99%

“…Magnesium alloys are among the potential candidates for applications in aerospace, automobile and communication fields, etc., due to their properties of high specific strength, low density, good machinability and low elastic modulus [1,2]. However, the widespread applications of Mg alloys are limited by their poor corrosion resistance, which is mainly attributed to their high reacting activity [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Protective Performance of a Mg-Rich Primer Containing Aluminum Tri-Polyphosphate on AZ91D Magnesium Alloy in Simulated Acid Rain

Sun

Fan

et al. 2019

Coatings

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Mg-rich primer (MRP) containing aluminum tri-polyphosphate functions via a galvanic mechanism to protect AZ91D alloy from corrosion in the 3 wt % NaCl solution. However, its protective performance can be strongly affected by the testing environment. Therefore, it is important to investigate the performance of the primer on magnesium alloys in an acid rain environment. In the present study, the protective performance of MRP with or without aluminum tri-polyphosphate was investigated via open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) in the simulated acid rain. Compared to the primer without aluminum tri-polyphosphate, the MRP containing aluminum tri-polyphosphate pigments exhibited better protective performance in the simulated acid rain condition. In the initial stage, the acidic condition prompted the aluminum tri-polyphosphate pigments to release phosphates and H+ to form magnesium phosphates on Mg particles, retarding their consumption rate. The Mg-rich primer with aluminum tri-polyphosphate can provide cathodic protection to AZ91D alloy for about 49 days in the simulated acid rain solution. Simultaneously, the corrosion products of Mg particles, magnesium oxides and phosphates, precipitated on the Mg particles and improved the stability of the primer. In addition, a protective film, consisting of magnesium oxides and phosphates, formed on the AZ91D substrate. Consequently, all these factors contributed to the long cathodic protection and improved corrosion resistance of MRP containing aluminum tri-polyphosphate in the simulated acid rain.

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Section: Eis Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of Protective Performance of a Mg-Rich Primer Containing Aluminum Tri-Polyphosphate on AZ91D Magnesium Alloy in Simulated Acid Rain

Sun

Fan

et al. 2019

Coatings

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“…Sealing the pores provides long-term corrosion protection and can be achieved via different surface post-treatments, including immersion in solutions with inorganic and/or organic compounds [ 263 , 264 , 265 ], the application of sol-gels [ 266 , 267 , 268 , 269 ], electrophoretic deposition [ 270 , 271 ], electrodeposition [ 272 ], thermosetting polymers [ 273 , 274 ], and other top-coats [ 275 , 276 , 277 ]. These post-treatments can also be used with the aim of adding functionality to the surface, e.g., hydrophobicity, aesthetics, etc.…”

Section: Post-treatmentmentioning

confidence: 99%

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

et al. 2022

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Although hexavalent chromium-based protection systems are effective and their long-term performance is well understood, they can no longer be used due to their proven Cr(VI) toxicity and carcinogenic effect. The search for alternative protection technologies for Mg alloys has been going on for at least a couple of decades. However, surface treatment systems with equivalent efficacies to that of Cr(VI)-based ones have only begun to emerge much more recently. It is still proving challenging to find sufficiently protective replacements for Cr(VI) that do not give rise to safety concerns related to corrosion, especially in terms of fulfilling the requirements of the transportation industry. Additionally, in overcoming these obstacles, the advantages of newly introduced technologies have to include not only health safety but also need to be balanced against their added cost, as well as being environmentally friendly and simple to implement and maintain. Anodizing, especially when carried out above the breakdown potential (technology known as Plasma Electrolytic Oxidation (PEO)) is an electrochemical oxidation process which has been recognized as one of the most effective methods to significantly improve the corrosion resistance of Mg and its alloys by forming a protective ceramic-like layer on their surface that isolates the base material from aggressive environmental agents. Part II of this review summarizes developments in and future outlooks for Mg anodizing, including traditional chromium-based processes and newly developed chromium-free alternatives, such as PEO technology and the use of organic electrolytes. This work provides an overview of processing parameters such as electrolyte composition and additives, voltage/current regimes, and post-treatment sealing strategies that influence the corrosion performance of the coatings. This large variability of the fabrication conditions makes it possible to obtain Cr-free products that meet the industrial requirements for performance, as expected from traditional Cr-based technologies.

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“…The increase in cross-linking density will result in a compact, continuous and defect-free surface morphology, [17][18][19] which is highly desirable to play an inhibitory role in controlling the corrosion behaviour of underlying metal components. 20 Accordingly, we observed variations in the surface morphology of the sol-gel coating prior to and aer GPTMS and 2-methylimidazole modication by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).…”

Section: Formation Mechanism Of the Modied Sol (Sizr-gh) Coatingmentioning

confidence: 99%

Endowing magnesium with the corrosion-resistance property through cross-linking polymerized inorganic sol–gel coating

et al. 2021

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Low temperature UV assisted sol-gel preparation of ZrO2 pore-sealing films on micro-arc oxidized magnesium alloy AZ91D and their electrochemical corrosion behaviors

Cited by 27 publications

References 37 publications

Investigation of Protective Performance of a Mg-Rich Primer Containing Aluminum Tri-Polyphosphate on AZ91D Magnesium Alloy in Simulated Acid Rain

Investigation of Protective Performance of a Mg-Rich Primer Containing Aluminum Tri-Polyphosphate on AZ91D Magnesium Alloy in Simulated Acid Rain

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

Endowing magnesium with the corrosion-resistance property through cross-linking polymerized inorganic sol–gel coating

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