Effects of the Duration of Potentiostatic Anodizing on the Corrosion Resistance and Surface Morphology of Films Formed on Mg-Al Alloys

2005 ◽  
Vol 486-487 ◽  
pp. 125-128 ◽  
Author(s):  
Seong Jong Kim ◽  
Seok Ki Jang ◽  
Jeong Il Kim
Keyword(s):  
Corrosion Resistance ◽  
Surface Morphology ◽  
Anodic Oxide ◽  
Al Alloys ◽  
Anodic Film ◽  
Al Alloy ◽  
Active Dissolution ◽  
Dissolution Reaction ◽  
Alloy Az91 ◽  
Morphology Of Films

The effects of the duration of potentiostatic anodizing on the corrosion resistance and surface morphology of anodic oxide films formed on Mg-Al alloy (AZ91) in 1 M NaOH were investigated. With the formation of an anodic film, the current density decreased gradually, started to stabilize at 300 s, and was relatively constant at 600 s. These results may be related to the increased time for catalysis of the active dissolution reaction, which not only enlarges the area covered by the anodic film, but also produces a more coherent, thicker film. The reference corrosion potentials of the anodic oxide film for AZ91 shifted in the noble direction with time. In general, the corrosion resistance characteristics were improved with anodizing time.

Effects of RPM, Bath Temperature and Anodizing Time in Anodizing for Mg-Al Alloy under Constant Current

2007 ◽  
Vol 544-545 ◽  
pp. 291-294
Author(s):  
Seong Jong Kim ◽  
Jeong Il Kim
Keyword(s):  
Anodic Oxide ◽  
Bath Temperature ◽  
Constant Current ◽  
Al Alloy ◽  
Optimum Conditions ◽  
Constant Current Density ◽  
Active Dissolution ◽  
Dissolution Reaction ◽  
Naoh Solution ◽  
Time Required

We studied the effects of solution RPM, bath temperature, and time in anodizing AZ91 under a constant current density of 750 mA/cm2 in a 1 M NaOH solution. In general, increasing the anodizing time, RPM, and temperature of the bath improved the corrosion resistance. The thickness of the anodic oxide film likely grew by increasing the time required to generate the active dissolution reaction. When anodizing at 750 mA/cm2, we evaluated a 300–3600-s range in anodizing time, 0–1500 RPM, and 296–373 K bath temperatures, and determined that 3600 s, 1500 RPM, and 373 K comprised the optimum conditions.

Surface Morphology Characteristics and Improvements on Corrosion Resistance in Anodized Mg-Al Alloys as a Result of Sealing Treatments

2005 ◽  
Vol 486-487 ◽  
pp. 129-132 ◽  
Author(s):  
Seong Jong Kim ◽  
Jeong Il Kim ◽  
Masazumi Okido
Keyword(s):  
Corrosion Resistance ◽  
Surface Morphology ◽  
Corrosion Potential ◽  
Al Alloys ◽  
Anodic Film ◽  
Distilled Water ◽  
Morphology Characteristics

The effects of sealing solutions on the corrosion resistance of anodized Mg-Al alloys were investigated. As the proportion of Mg(OH)2 increases with the increase in the NaOH concentration, the corrosion potential improves. The sealing effects were further improved by increasing the temperature of distilled water, the pH of solutions, and the proportion of Mg(OH)2 present in the anodic film.

Effects of Anodizing Time on Anodizing of Mg-Al Alloy in Alkaline Solution

2006 ◽  
Vol 510-511 ◽  
pp. 686-689
Author(s):  
Seong Jong Kim ◽  
Jeong Il Kim
Keyword(s):  
Oxide Film ◽  
Film Thickness ◽  
Alkaline Solution ◽  
Anodic Oxide ◽  
Anodic Oxide Film ◽  
Al Alloy ◽  
Active Dissolution ◽  
Dissolution Reaction ◽  
Edx Analyses ◽  
Time Required

This paper investigated the effects of anodizing time on the formation of anodic oxide films on a Mg-Al alloy in alkaline solution. The thickness of the anodic oxide film was increased by increasing the time required to generate the active dissolution reaction. When anodizing at various anodizing time, the potential after passivity increased with time, which implies growth in film thickness. When the anodizing time was varied, the quantity of oxygen increased with time in the white areas (the film), i.e., more film was observed in the SEM and EDX analyses.

Effect of Voltage on Mg-Li-Al Alloy Anodic Oxide Film

2018 ◽  
Vol 941 ◽  
pp. 1194-1197 ◽  
Author(s):  
Naoya Miyakita ◽  
Natsuki Tanigaki ◽  
Taiki Morishige ◽  
Toshihide Takenaka
Keyword(s):  
Oxide Film ◽  
Phosphoric Acid ◽  
Anodic Oxidation ◽  
Surface Coating ◽  
Low Voltage ◽  
Active Surface ◽  
Anodic Oxide ◽  
Al Alloys ◽  
Anodic Oxide Film ◽  
Al Alloy

Anodic oxidation of Mg-Li-Al alloys using phosphoric acid-based bath were processed to obtain the corrosion-proof surface coating. The specimen oxidized at low voltage anodically dissolved without the formation of oxidized film. Anodic oxidation film could be formed at higher voltage due to thin layer preferentially formed on tthe active surface, this layer develops to stable thick film. There were no significant differences in film thickness between LA141 and LA143 alloys.

Effects of Current Density on the Formation of Anodic Oxide Films on AZ91

2006 ◽  
Vol 510-511 ◽  
pp. 166-169
Author(s):  
Seong Jong Kim ◽  
Jeong Il Kim
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Anodic Polarization ◽  
Oxide Films ◽  
Anodic Oxide ◽  
Anodic Polarization Curve ◽  
Al Alloy ◽  
Anodic Oxide Films ◽  
Active Metal ◽  
Naoh Solution

Magnesium must be surface treated to prevent corrosion, since it is a very active metal electrochemically. On anodizing, a compact film several tens of micrometers thick forms on magnesium, which imparts good corrosion resistance. The Mg-Al alloy (AZ91) was anodized in 1 M NaOH solution. The surface morphology of the anodized films was observed using scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), and electrochemical methods. The effects of current density on the formation of anodic oxide films for a Mg-Al alloy in 1 M NaOH were investigated. In the anodic polarization curve, the reference corrosion potentials were far greater at 4-9 mA/cm2 than at 1 mA/cm2. The film that formed at 1 mA/cm2 was thin, suggesting that parts of the film had been dissolved or destroyed during the anodic polarization test. Corrosion resistance differed owing to concentric differences in current flow. Thick anodic oxide films were formed at higher applied currents.

Effect of Cu2+ Doped in Sol on Properties of Sealed Film on Anodized Al Alloy

2010 ◽  
Vol 33 ◽  
pp. 290-294
Author(s):  
Qi Zhou ◽  
Xin Wang ◽  
Li Fang Zhang ◽  
Xin Ma ◽  
H.B. Li ◽  
...  
Keyword(s):  
Phase Transition ◽  
Staphylococcus Aureus ◽  
Corrosion Resistance ◽  
Antibacterial Property ◽  
Anodic Oxide ◽  
Anodic Oxide Film ◽  
Heating Process ◽  
Al Alloy ◽  
Alumina Sol ◽  
The One

The corrosion resistance of anodic oxide film sealed with alumina sol can improved. Cu2+ was put into the alumina sol so that antibacterial property was endowed to the sealed film. Composition, morphology and corrosion resistance of sealed film doped with Cu2+ were studied by DSC, EIS and SEM etc. The film sealed by doping Cu2+ in sol has less and narrower crack on the surface than the one without Cu2+. The gel without Cu2+ has more chemical reaction and phase transition than that with Cu2+ in the heating process observing from the DSC curve, which results in more cracks on the surface of sealed films without Cu2+. Sol doped with Cu2+ can enhance corrosion resistance inferred from the polarization curve, in a way. The films sealed by sol with Cu2+ have a good antibacterial on Staphylococcus aureus. The antibacterial rate is more than 99%. The results show sol doped Cu2+ not only improve corrosion resistance but also have antibacterial property.

scholarly journals One-Step Potentiostatic Deposition of Micro-Particles on Al Alloy as Superhydrophobic Surface for Enhanced Corrosion Resistance by Reducing Interfacial Interactions

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 392 ◽  
Author(s):  
Tian Shi ◽  
Xuewu Li ◽  
Qiaoxin Zhang ◽  
Ben Li
Keyword(s):  
Corrosion Resistance ◽  
Al Alloys ◽  
Water Repellent ◽  
Al Alloy ◽  
Interfacial Interactions ◽  
Sliding Angle ◽  
Water Contact ◽  
Corrosion Failure ◽  
Micro Particles ◽  
One Step

Corrosion failure is a thorny problem that restricts the application of Al alloys. As a new technique for functional realization, hydrophobic preparation offers an efficient approach to solve corrosion problem. This work has developed a facile and low-cost method to endow Al alloy with enhanced water-repellent and anticorrosion abilities. The micro-particles have been firstly prepared by one-step deposition process. Furthermore, wetting and electrochemical behaviors of as-prepared structures have been investigated after silicone modification. Results show that the fabricated surface possesses excellent superhydrophobicity with a water contact angle (CA) of 154.7° and a sliding angle (SA) of 6.7°. Meanwhile, the resultant surface is proved with enhanced corrosion resistance by reducing interfacial interactions with seawater, owing to newly-generated solid-air-liquid interfaces. This work sheds positive insights into extending applications of Al alloys, especially in oceaneering fields.

scholarly journals Corrosion Behavior of Fe-Ni-Al Alloy Inert Anode in Cryolite Melts

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 399 ◽  
Author(s):  
Pingping Guan ◽  
Aimin Liu ◽  
Zhongning Shi ◽  
Xianwei Hu ◽  
Zhaowen Wang
Keyword(s):  
Inert Anode ◽  
Aluminum Electrolysis ◽  
Al Alloys ◽  
Al Alloy ◽  
Protective Film ◽  
Active Dissolution ◽  
Corrosion Resistant ◽  
Inert Anodes ◽  
Passivation Potential ◽  
Tafel Curve

Fe-Ni-based alloys are promising materials of inert anodes for use in aluminum electrolysis and adding Al can further improve the corrosion resistance. Fe-Ni-Al alloys with 1.4–8.6 wt.% Al were prepared by vacuum melting, and their corrosion as anodes during the production of pure Al (98.14–99.68%) by electrolysis was studied in a melt of NaF-AlF3-NaCl-CaF2-Al2O3 at 850 °C. The corrosion layer on the anode contains fluorine salt that corrodes the oxide film, and the inner layer is Ni-enriched while the outer layer is enriched with Fe and O due to the preferential oxidation of Fe. The electrolytically deposited oxide films on Fe-Ni-Al alloys with different compositions contains Fe2O3, Fe3O4, NiO, Al2O3, FeAl2O4, NiFe2O4, and other protective oxides, making the alloys very corrosion-resistant. The linear voltammetric curves can be divided into three parts: active dissolution, passivation transition, and over-passivation zones. The alloy with 3.9 wt.% Al (57.9Fe-38.2Ni-3.9Al) has a relatively negative passivation potential, and therefore, is easier to become passivated. According to the Tafel curve, this alloy shows a relatively positive corrosion potential as anode (1.20 V vs. Al/AlF3), and thus can form a protective film.

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