A new, bright and hard aluminum surface produced by anodization

Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.486-487.125 ◽

2005 ◽

Vol 486-487 ◽

pp. 125-128 ◽

Cited By ~ 1

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.

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ESTUDIO DE LA RESISTENCIA A LA CORROSION DEL ALUMINIO 6063 ANODIZADO

Revista TECNIA ◽

10.21754/tecnia.v22i2.77 ◽

2017 ◽

Vol 22 (2) ◽

pp. 17

Author(s):

Karín Paucar Cuba ◽

Hugo Rojas Flores ◽

Abel Vergara Sotomayor

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Sulfuric Acid ◽

Electrochemical Impedance ◽

Salt Spray ◽

Aluminum Surface ◽

Equivalent Circuits ◽

Acid Salt ◽

Mass Losses ◽

Palabras Clave

El estudio de la resistencia a la corrosión del anodizado de una aleación de aluminio (AA6063) en ácido sulfúrico a diferentes tiempos de anodizado: 30, 45 y 60 min. se realizó usando la espectroscopia de impedancia electroquímica (EIE) y el ensayo de niebla salina ácida. (ASTM B287). Los datos obtenidos por EIE y su correlación con los circuitos equivalentes más apropiados permitieron determinar los parámetros asociados a la capa porosa y a la capa barrera del óxido protector formado sobre la superficie del aluminio en estudio. La exposición de las muestras anodizadas durante 250h a una niebla salina ácida permitió observar variaciones en su masa. De los resultados obtenidos por EIE y las pérdidas de masa de las muestras anodizadas se estableció que la película de anodizado de 45 minutos mostró una mayor resistencia a la corrosión en comparación con la obtenida a 60 y 30 min., respectivamente. Palabras clave.- Aluminio, Anodizado, Impedancia electroquímica, Niebla salina ácida. ABSTRACTThe study of the corrosion resistance of anodized on aluminum alloy (AA6063) in sulfuric acid to different times: 30, 45 and 60 min. was performed using electrochemical impedance spectroscopy (EIS) and the acid salt spray test (ASTM B287). The EIS’data and its correlation with the most appropriate equivalent circuits allowed to determine the parameters associated with the porous layer and the oxide layer protective barrier formed on the aluminum surface under study. Exposure of the samples anodized for a 250h salt spray acid allowed to observe changes in their mass. From the results obtained by EIS and the mass losses of the anodized samples was established that the anodized film of 45 minutes showed higher corrosion resistance compared to that obtained at 60 and 30 min, respectively. Keywords.- Aluminum, Anodized, Electrochemical impedance, Acid salt spray.

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Ultrasonic Sensors-Assisted Corrosion Studies on Surface Coated AlSi9Cu3 Alloy Die Castings

Coatings ◽

10.3390/coatings10010085 ◽

2020 ◽

Vol 10 (1) ◽

pp. 85

Author(s):

Yuh-Chung Hu ◽

Senthil Kumaran Selvaraj ◽

Manivannan Subramanian ◽

Kathiravan Srinivasan ◽

Srinivasan Narayanan

Keyword(s):

Corrosion Resistance ◽

Die Casting ◽

Pure Aluminum ◽

Salt Spray ◽

Salt Spray Test ◽

Al Alloy ◽

Neutral Salt ◽

Powder Coatings ◽

Acrylic Paint ◽

Epoxy Primer

A novel phenomenon known as Industry X.0 is becoming extremely popular for digitizing and reinventing business organizations through the adaption of rapid and dynamic technological, innovational, and organizational changes for attaining the profitable revenue. This work investigates the die-casted commercially pure aluminum alloyed with 9% silicon and 3% copper (AlSi9Cu3) that is produced through the gravity die casting process. Further, the degradation of surface coating on die-casted AlSi9Cu3 alloy was explored. The acrylic paint electrodeposition (ED) coat, 2-coat polyester without primer and 3-coat polyester with epoxy primer powder coatings were used in this study. Moreover, the 3.5 wt.% of sodium chloride (3.5 wt.% of NaCl) test solution was used for electrochemical and salt spray test and the tools used to assess electrochemical properties were electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and neutral salt spray test (NSS). The microstructure of AlSi9Cu3 after corrosion exposure was investigated; also, the microstructure of coated and uncoated AlSi9Cu3 samples was analyzed by SEM microscopy after corrosion exposure. Besides, the electrochemical studies were also carried out on the Al alloy die casting. It was found that acrylic paint ED coatings exhibited higher corrosion resistance than 2-coat polyester without primer & 3-coat polyester with epoxy primer powder coatings. Acrylic paint ED coating showed higher corrosion resistance in AC and a lower value in DC and 3-coat polyester with epoxy primer powder coating displayed higher corrosion resistance in DC and a lower value in AC.

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The formation of a hydrotalcite coating on the aluminium alloy 6060 using a spray system

Clay Minerals ◽

10.1180/claymin.2015.050.5.03 ◽

2015 ◽

Vol 50 (5) ◽

pp. 583-592 ◽

Cited By ~ 1

Author(s):

Lingli Zhou ◽

Henrik Friis ◽

Melanie Roefzaad ◽

Kasper Bondo Hansen ◽

Sara Eisenhardt ◽

...

Keyword(s):

Corrosion Resistance ◽

Aluminium Alloy ◽

Layer Structure ◽

Salt Spray ◽

Al Alloy ◽

Acetate Solution ◽

Average Thickness ◽

Spray System ◽

Filiform Corrosion ◽

Better Than

AbstractCoatings with the composition of Li-Al-NO3 hydrotalcite were formed on the Al alloy 6060 using a spray system. The coatings consist of crystals with a typical hydrotalcite structure. Dense, uniform and blade-like flakes cover completely the surface of the Al substrate. The coatings display a multi-layer structure with average thickness of ∼1000 nm. The hydrotalcite-coated samples performed better than those without coatings in salt-spray and filiform-corrosion tests, and further treatment involving sealing with a Mg acetate solution and dipping in a H2O2 + Ce-based solution improved the corrosion resistance ability.

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Wear and Corrosion Resistance of Plasma Electrolytic Oxidation Coatings on 6061 Al Alloy in Electrolytes with Aluminate and Phosphate

Materials ◽

10.3390/ma14144037 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4037

Author(s):

Zhenjun Peng ◽

Hui Xu ◽

Siqin Liu ◽

Yuming Qi ◽

Jun Liang

Keyword(s):

Corrosion Resistance ◽

Plasma Electrolytic Oxidation ◽

Salt Spray ◽

P Element ◽

Alumina Coating ◽

Al Alloy ◽

Wear Properties ◽

Electrolytic Oxidation ◽

Plasma Electrolytic ◽

Peo Coatings

Phosphate and aluminate electrolytes were used to prepare plasma electrolytic oxidation (PEO) coatings on 6061 aluminum alloy. The surface and cross-section microstructure, element distribution, and phase composition of the PEO coatings were characterized by SEM, EDS, XPS, and XRD. The friction and wear properties were evaluated by pin-on-disk sliding tests under dry conditions. The corrosion resistance of PEO coatings was investigated by electrochemical corrosion and salt spray tests in acidic environments. It was found that the PEO coatings prepared from both phosphate and aluminate electrolytes were mainly composed of α-Al2O3 and γ-Al2O3. The results demonstrate that a bi-layer coating is formed in the phosphate electrolyte, and a single-layered dense alumina coating with a hardness of 1300 HV is realizable in the aluminate electrolyte. The aluminate PEO coating had a lower wear rate than the phosphate PEO coating. However, the phosphate PEO coating showed a better corrosion resistance in acidic environment, which is mainly attributed to the presence of an amorphous P element at the substrate/coating interface.

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Anti-Corrosion Property of Atomic Layer Deposition Films for Anodized Aluminum

Materials Science Forum ◽

10.4028/www.scientific.net/msf.809-810.689 ◽

2014 ◽

Vol 809-810 ◽

pp. 689-694

Author(s):

Yi Jia ◽

Mang Yang ◽

Wei Er Lu ◽

Feng Ji ◽

Chao Bo Li ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Film Thickness ◽

Salt Spray ◽

Atomic Layer ◽

Processing Parameters ◽

Corrosion Property ◽

Anodized Aluminum ◽

Al2o3 Layer ◽

Layer Deposition ◽

Pore Sealing

Single and multilayer of Al2O3 and TiO2 were fabricated on anodized aluminum by atomic layer deposition. The effect of processing parameters on pore sealing and anti-corrosion property was studied. It is concluded that the micropores on anodized aluminum could be sealed by atomic layer deposition oxide films through SEM and staining experiments. The anti-corrosive property is affected mainly by the film thickness and process temperature. The acidic drip and salt spray test shows that the anti-corrosion property is enhanced as the film thickness increase. With the similar thickness, Al2O3/TiO2 multilayer film has the best anti-corrosion property, while the single Al2O3 layer appears the poorest. The complementary roles between two basic materials result in the enhanced application property.

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

Coatings ◽

10.3390/coatings8110392 ◽

2018 ◽

Vol 8 (11) ◽

pp. 392 ◽

Cited By ~ 1

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.

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Corrosion Behavior of Selectively Laser Melted CoCrFeMnNi High Entropy Alloy

Metals ◽

10.3390/met9101029 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1029 ◽

Cited By ~ 9

Author(s):

Jie Ren ◽

Chaitanya Mahajan ◽

Liang Liu ◽

David Follette ◽

Wen Chen ◽

...

Keyword(s):

Corrosion Resistance ◽

Laser Processing ◽

Electrochemical Impedance ◽

Processing Parameters ◽

High Entropy Alloy ◽

Elemental Distribution ◽

Powder Bed ◽

High Entropy ◽

Wide Range ◽

Superior Corrosion Resistance

CoCrFeMnNi high entropy alloys (HEAs) were additively manufactured (AM) by laser powder bed fusion and their corrosion resistance in 3.5 wt% NaCl solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests. A systematic study of AM CoCrFeMnNi HEAs’ porosity under a wide range of laser processing parameters was conducted and a processing map was constructed to identify the optimal laser processing window for CoCrFeMnNi HEAs. The near fully dense AM CoCrFeMnNi HEAs exhibit a unique non-equilibrium microstructure consisting of tortuous grain boundaries, sub-grain cellular structures, columnar dendrites, associated with some processing defects such as micro-pores. Compared with conventional as-cast counterpart, the AM CoCrFeMnNi HEAs showed higher pitting resistance (ΔE) and greater polarization resistance (Rp). The superior corrosion resistance of AM CoCrFeMnNi HEAs may be attributed to the homogeneous elemental distribution and lower density of micro-pores. Our study widens the toolbox to manufacture HEAs with exceptional corrosion resistance by additive manufacturing.

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One-Step Preparation of Super-Hydrophobic Micro-Nano Dendrites on Al Alloy for Enhanced Corrosion Resistance

Metals ◽

10.3390/met8110960 ◽

2018 ◽

Vol 8 (11) ◽

pp. 960 ◽

Cited By ~ 4

Author(s):

Xuewu Li ◽

Tian Shi ◽

Ben Li ◽

Chuanwei Zhang ◽

Bin Zhong ◽

...

Keyword(s):

Corrosion Resistance ◽

Low Cost ◽

Hydrophobic Surface ◽

Al Alloys ◽

Al Alloy ◽

Ocean Engineering ◽

Acid Modification ◽

Sliding Angle ◽

Corrosion Failure ◽

One Step

Corrosion failure is a thorny issue that restricts the applications of Al alloys. As a research hotspot in functional realization, hydrophobic fabrication exactly offers an efficient method to settle metallic corrosions. This work has developed a facile and low-cost method to enhance corrosion resistance of Al alloys. The micro-nano dendrites have been firstly prepared on metallic substrate using one-step potentiostatic deposition. Then, wetting and electrochemical behaviors have been systematically investigated after stearic acid modification. Results show that the as-prepared surface possesses amplified and durable water repellence with an apparent contact angle (CA) of 154.2° and a sliding angle (SA) of 4.7°. Meanwhile, owing to the trapped air in dendrites, the newly-generated solid-air-liquid interfaces help to resist seawater penetration by reducing interfacial interactions on the super-hydrophobic surface as well as significantly enhance its corrosion resistance. This work sheds positive insights into extending the applications of Al alloys in many areas, especially for ocean engineering fields.

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Protective Cerium-Based Layered Double Hydroxides Thin Films Developed on Anodized AA6082

Advances in Materials Science and Engineering ◽

10.1155/2020/5785393 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Muhammad Ahsan Iqbal ◽

Michele Fedel

Keyword(s):

Thin Films ◽

Corrosion Resistance ◽

Electrochemical Impedance ◽

Barrier Properties ◽

Hot Water ◽

Aluminum Surface ◽

Anodized Aluminum ◽

Immersion Period ◽

Double Hydroxides

In this work, CeMgAl-LDHs protective thin films were developed directly on the anodized aluminum surface, and on the “hot water-sealed” anodized aluminum specimens. The synthesized coatings were investigated by SEM-EDS and XRD and through long-term electrochemical impedance spectroscopy (EIS) spectra. The growth of CeMgAl-LDHs into/onto the micropores/defects of anodized film was found to significantly improve the LDH barrier properties with delaying coating degradation compared to LDHs developed on the “hot water-sealed” surface. The unmodified LDHs “without cerium addition” were also developed to compare the influence of cerium on the structural and electrochemical properties of LDHs. It is also noteworthy that LDHs grown on the anodized surface provided dense and finer growth, while the addition of cerium ions was found to exhibit influential higher long-term corrosion resistance properties after the 1200 h immersion period.

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