Phase transitions in alumina films during post-sparking anodising of Al alloys

Bousser, Étienne; Rogov, Aleksey B.; Shashkov, P.; Gholinia, Ali; Laugel, Nicolas; Slater, Thomas J. A.; Withers, Philip J.; Matthews, A.; Yerokhin, Aleksey

doi:10.1016/j.actamat.2022.118587

Cited by 16 publications

(6 citation statements)

References 77 publications

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“…The overall weight loss are about 11% and it was recorded between 450 • C and 600 • C, corresponding to the ceramic conversion process. At about 800 • C, the conversion was completed, and the weight remained stable up to 1200 • C. These results are consistent with the information found in the literature [27], in two fundamental steps were identified: the first in the temperature range 200-400 °C and the second at 500-750 °C. In particular, at temperatures above 200 °C, there is a further radical polymerization of residual vinyl groups.…”

Section: Resultssupporting

confidence: 92%

“…Plasma Electrolytic Oxidated (PEO) aluminum (Al in the text) slabs have been provided by Cambridge Nanolitic, Cambridge, UK, consisting of Al (20-70 µm coated) measured using eddy currents, as reported in [26], and thick alpha and gamma nano alumina (crystallite size 30-80 nm) obtained via proprietary soft sparking PEO technology. The average grain size was derived using X-ray diffraction measurements, as reported in [26,27]. The treatment was conducted in a phosphate-silicate electrolyte maintained at room temperature of 25 • C with the use of bipolar electrical pulses with 700 V amplitude and repetition frequency of 2 KHz.…”

Section: Methodsmentioning

confidence: 99%

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Joining and Coating of Plasma Electrolytic Oxidated Aluminum Using a Silica Preceramic Polymer

Ferraris,

Benelli,

Casalegno

et al. 2024

Coatings

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This study evaluates the effectiveness of a silica preceramic polymer for joining and coating Plasma Electrolytic Oxidated (PEO) aluminum components at temperatures below 200 °C. PEO aluminum slabs were coated and joined with a silica precursor polymer (Durazane1800, Merck, Darmstadt, Germany), both with and without the addition of 48 wt% silica nanoparticles, and cured at 180 °C for 4 h in air. Thermogravimetric analysis assessed the curing process and thermal stability, while X-ray diffraction confirmed the polymer’s conversion to amorphous silica after heating at 1200 °C. Resistance to humid environments was tested by soaking coated samples in tap water for a week, with no mass variation observed. Mechanical testing through tensile mode and tensile lap tests showed that adding 48 wt% silica nanoparticles significantly improved joint cohesion and nearly quadrupled mechanical strength. Fracture surfaces were examined using Field Emission Scanning Electron Microscopy, and composition analysis was performed with Energy Dispersion X-ray Spectroscopy. Crack detection was conducted using Computer Tomography with an in situ bending test setup to obtain the mechanical resistance of the PEO coating. The results indicate that the silica preceramic polymer is suitable for joining and coating PEO aluminum components, with silica nanoparticles enhancing mechanical strength and providing excellent thermal stability and resistance to humidity.

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Section: Resultssupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Joining and Coating of Plasma Electrolytic Oxidated Aluminum Using a Silica Preceramic Polymer

Ferraris,

Benelli,

Casalegno

et al. 2024

Coatings

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“…The α-Al 2 O 3 phase appeared and remained predominant after 30-60 min due to the development of micro-discharges during the PEO process. Similar results have been obtained by other scientists [40].…”

Section: Peo Methodssupporting

confidence: 92%

Possibility of Phase Transformation of Al2O3 by a Laser: A Review

Matijošius,

Padgurskas,

Bikulčius

2024

Crystals

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Aluminum (Al) components of high quality often require an optimal ratio of lightness and favorable mechanical properties. In order to improve the physical-mechanical properties of Al, an aluminum oxide (Al2O3) film is usually formed on the surface of Al, which itself is characterized by high strength, hardness, corrosion resistance, and other technical properties. Unfortunately, depending on the conditions, the oxide film may be formed from different crystal phases on the Al surface, which are not always of desirable quality, i.e., the α-Al2O3 phase. The present review demonstrates that the properties of the Al2O3 film may be improved by Al processing with a laser beam according to the scheme: Al (Al alloy) → electrochemical anodizing → treatment with laser irradiation → α-Al2O3. Both Al substrate and the anodizing electrolyte affect the phase transformation of anodic Al2O3. Laser irradiation of the Al2O3 surface leads to high heating and cooling rates, which may promote the formation of a highly crystalline α-Al2O3 phase on anodic Al2O3.

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“…For instance, in corrosive marine conditions, aluminum alloy surfaces are vulnerable to extensive and haphazard corrosion damage, resulting in stress concentration and ultimately reducing the structure's lifespan [6][7][8][9][10]. The aluminum alloys are extensively used in the aerospace, automotive, shipbuilding, and high-speed rail industries due to their high strength-to-weight ratio, which is particularly beneficial for reducing structural weight [11][12][13][14][15][16][17][18]. Moreover, these alloys are commonly employed as medium-strength structural materials, offering advantages such as excellent weldability, corrosion resistance, and immunity to stress-corrosion cracking.…”

Section: Introductionmentioning

confidence: 99%

Revealing Crack Propagation and Mechanical Behavior of Corroded Aluminum Alloys

Zhang,

Wang,

Fang

et al. 2024

Symmetry

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The mechanical properties and crack propagation behavior of aluminum alloys, both with and without corroded surfaces, were thoroughly investigated through molecular dynamic (MD) simulations. The study delved into the effects of corrosion depth and width on the mechanical properties of corroded aluminum alloys. It was found that as the corrosion depth increases, the yield strength experiences an initial decrease followed by a subsequent increase. This can be attributed to the impact of increased corrosion depth on the healing of surface roughness, which ultimately leads to significant changes in yield strength. Furthermore, the presence of corrosion pits was identified as a key factor in regulating the local microstructure evolution within the material, leading to pronounced differences in stress distribution localization. This, in turn, influenced the path of crack propagation within the material. These findings not only contribute to a deeper understanding of the behavior of aluminum alloys under corrosion, but also provide valuable insights for the development of aluminum alloys with enhanced mechanical properties.

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Phase transitions in alumina films during post-sparking anodising of Al alloys

Cited by 16 publications

References 77 publications

Joining and Coating of Plasma Electrolytic Oxidated Aluminum Using a Silica Preceramic Polymer

Joining and Coating of Plasma Electrolytic Oxidated Aluminum Using a Silica Preceramic Polymer

Possibility of Phase Transformation of Al2O3 by a Laser: A Review

Revealing Crack Propagation and Mechanical Behavior of Corroded Aluminum Alloys

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