Borate's effects on coatings by PEO on AZ91D alloy

Gu, Chaofeng; Wang, Linlin; Hu, Xin; Wu, Dong Yang; DaCosta, Herbert

doi:10.1080/02670844.2017.1287622

Cited by 10 publications

(4 citation statements)

References 32 publications

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“…The existence of the O element is inferred to be related to the oxidation of active metallic atoms on the cross-section of the AZ91D magnesium alloy specimen. From the microstructure observation of the coating, it could be inferred that the formation of the coating is not a simple solid diffusion process, liquid phase should also be involved in the surface alloying process, since a pure solid diffusion process is driven by the concentration gradient which commonly results in a layer structure, while solidification of a molten phase is prone to result in a network shape eutectic multiple-phase-microstructure [10]. The existence of a liquid phase in the diffusion alloying process is reasonable [22], because the eutectic temperature in the Mg-Zn binary system could even be 341 °C, according to the Mg-Zn binary phase diagram [20].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

A Zinc-Rich Coating Fabricated on a Magnesium Alloy by Oxide Reduction

Huang

Duan

2019

Coatings

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The corrosion resistance of magnesium alloys could be enhanced by covering metallic coatings on the surface. The zinc-rich coating is one of these metallic coatings. To fabricate a zinc-rich coating on magnesium alloys, the substrate should be pretreated carefully, and a protective atmosphere is usually required. In this research, a zinc-rich coating was successfully fabricated on the AZ91D magnesium alloy in air by a diffusion alloying method, with zinc oxide as the zinc source. At the same time, the pretreatment of the magnesium alloy matrix was greatly simplified. The as-diffusion-alloyed zinc-rich intermetallic layer was investigated, utilizing SEM, EDS, and XRD, respectively. It is inferred that zinc oxide was reduced into Zn atoms by the active Mg atoms, and the Mg atoms were coming from the magnesium alloy matrix. Then the Zn atoms passed through the oxide film and formed an intermetallic layer on the magnesium alloy surface. Thus, taking advantage of the activity of Mg atoms, magnesium alloys could be surface alloyed with oxides.

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Section: Resultsmentioning

confidence: 99%

“…Coatings are fabricated on the surface to enhance the corrosion resistance of magnesium alloys [7][8][9][10][11][12][13][14][15][16][17][18][19]. Among which, the zinc coating is an effective one.…”

Section: Introductionmentioning

confidence: 99%

A Zinc-Rich Coating Fabricated on a Magnesium Alloy by Oxide Reduction

Huang

Duan

2019

Coatings

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“…According to the data listed in Table 4, the PEO coating grown in the electrolyte containing borax (Na 2 B 4 O 7 ·10H 2 O) and without Si 3 N 4 nanoparticle additive has the highest corrosion resistance in the present work. Gu et al [55] reported that the PEO layer grown on Mg with borate and NaAlO 2 contained electrolytes had improved corrosion resistance. Apparently, the electrolytic compositions play a great role on the anticorrosion performance of PEO coating [56][57][58].…”

Section: Potentiodynamic Polarization Testsmentioning

confidence: 99%

Effects of Processing Parameters on the Corrosion Performance of Plasma Electrolytic Oxidation Grown Oxide on Commercially Pure Aluminum

Mengesha

Chu

Lou

et al. 2020

Metals

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The plasma electrolyte oxidation (PEO) process has been considered an environmentally friendly surface engineering method for improving the corrosion resistance of light weight metals. In this work, the corrosion resistance of commercially pure Al and PEO treated Al substrates were studied. The PEO layers were grown on commercially pure aluminum substrates using two different alkaline electrolytes with different addition concentrations of Si 3 N 4 nanoparticles (0, 0.5 and 1.5 gL −1 ) and different duty cycles (25%, 50%, and 80%) at a fixed frequency. The corrosion properties of PEO coatings were investigated by the potentiodynamic polarization and electrochemical impedance spectroscopy test in 3.5 wt.% NaCl solutions. It showed that the weight gains, layer thickness and surface roughness of the PEO grown oxide layer increased with increasing concentrations of Si 3 N 4 nanoparticles. The layer thickness, surface roughness, pore size, and porosity of the PEO oxide layer decreased with decreasing duty cycle. The layer thickness and weight gain of PEO coating followed a linear relationship. The PEO layer grown using the Na 2 B 4 O 7 ·10H 2 O contained electrolyte showed an excellent corrosion resistance and low surface roughness than other PEO coatings with Si 3 N 4 nanoparticle additives. It is noticed that the corrosion performance of PEO coatings were not improved by the addition of Si 3 N 4 nanoparticle in the electrolytic solutions, possibly due to its detrimental effect to the formation of a dense microstructure.Metals 2020, 10, 394 2 of 21 hardness restrict their wider application in crucial environments [1,2]. One of the efficient approaches to improve these disadvantages of aluminum is by surface modification for enhancing its anticorrosion performance, such as plasma electrolytic oxidation (PEO), ion implantation, laser surfacing, diffusion treatment, thermal spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD) and conversion coatings such as anodizing, etc. Among several kinds of surface modification techniques, PEO is one of the most promising surface treatment methods [3], because it is an environmentally friendly and cost-effective technique for surface engineering and a suitable method for producing thick, hard and dense ceramic coatings on light metals.PEO, also known as micro-arc oxidation (MAO) [4], is an electrochemical induced plasma surface treatment process for creating oxide ceramic coatings on light metals [5,6]. PEO is a relatively new surface modification technique which can significantly improve the hardness, corrosion and wear resistance, adhesion strength, thermal and other desirable properties of Al alloys by efficiently growing thick alumina rich ceramic coatings [7][8][9][10]. During this process, plasma discharge can cause the formation of a highly adhesive and dense oxide layer on the substrate [11,12]. PEO is also considered an environmentally friendly and cost-effective coating process with real industrial applications [3,[13][14][15][16][17][18]. Several par...

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“…The MAO coatings create a high porosity in the outer layer, and those formed on magnesium alloys are mainly composed of MgO with some phases related to electrolyte compositions [7][8][9][10]. Those structures are unstable, especially under aggressive environments.…”

Section: Introductionmentioning

confidence: 99%

Microarc oxidation coatings containing TiC and NbC on magnesium alloy

Tang

Feng

et al. 2019

Surface Engineering

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Microarc oxidation (MAO) coatings were formed on AZ91D magnesium alloy in zirconatephosphate electrolytes with and without the addition of titanium carbide (TiC) and niobium carbide (NbC) particles. Surface morphologies, structures, compositions and corrosion resistance of the MAO coatings were investigated. The MAO coating formed in the based electrolyte was mainly composed of MgO, Mg 2 Zr 5 O 12 and some amorphous phases. TiC and NbC particles in the electrolyte were incorporated and uniformly distributed in the MAO coatings. Both particles increased the thickness and compactness of the MAO coatings. Electrochemical measurements results indicated that the TiC and NbC particles in the electrolyte improved the corrosion resistance of the MAO coating, and those formed in the electrolyte with NbC particles showed the best corrosion resistance.

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Borate's effects on coatings by PEO on AZ91D alloy

Cited by 10 publications

References 32 publications

A Zinc-Rich Coating Fabricated on a Magnesium Alloy by Oxide Reduction

A Zinc-Rich Coating Fabricated on a Magnesium Alloy by Oxide Reduction

Effects of Processing Parameters on the Corrosion Performance of Plasma Electrolytic Oxidation Grown Oxide on Commercially Pure Aluminum

Microarc oxidation coatings containing TiC and NbC on magnesium alloy

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