Influence of the duty cycle on structural and mechanical properties of oxide layers on Al-1050 by a plasma electrolytic oxidation process

Song, Jeonghwan; Nam, Kyung-Su; Moon, Jung-In; Choi, Young Sang; Lim, Dae-Young

doi:10.1007/s12540-014-3025-2

Cited by 10 publications

(7 citation statements)

References 32 publications

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“…In addition, the band at 806 cm −1 was associated with stretching vibrations of Si−O bond in a magnesium silicate compound [54]. The bands observed between 518-400 cm −1 were attributed to Si-O and Mg-O bands, according to the literature [39]. These spectra did not reveal the presence of any hydroxide material, which was coherent with the chemical composition obtained from XRD analysis.…”

Section: Morphology Porosity and Chemical Composition Of Peo Anodic supporting

confidence: 80%

“…In addition, the mode of current application has a relevant impact on the morphology of the coating where unipolar currents produce porous and cracked coatings while bipolar currents result in coatings with low porosity and no cracks, but with low growth rates [38]. Additionally, low duty cycles produce high breaking voltages and high final voltages, promoting the formation of coatings with greater thickness and higher porosity but a smaller pore size, in contrast to high duty cycles [16,39]. Moreover, the duration of the PEO process is proportional to the roughness and porosity.…”

Section: Introductionmentioning

confidence: 99%

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New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

Toro

Zuleta

Correa

et al. 2020

Mater. Res. Express

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In this work, anodic oxide layers on the surface of an AZ31 magnesium alloy were obtained by plasma electrolytic oxidation (PEO) process under low frequency pulsed current. For this, electrolytical solutions containing hexamethylenetetramine and sodium fluoride were used. The morphology and chemical composition of formed coatings were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Also, salt spray test, hydrogen evolution and electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) were conducted in order to study the corrosion behavior of the coated samples. It was found that the use of low frequency pulsed current for the PEO process reduces the film porosity and increases its thickness, compared with PEO films obtained by continuous anodization. The effect of the pulsed current signal was also analyzed for a two steps PEO process, observing changes in the morphological characteristics of the coatings which allow a better corrosion according electrochemical tests (short term corrosion measurements). However, long term tests results as hydrogen evolution and salt spray tests, indicated the opposite. Both the film porosity and thickness were affected by either the pulsing of the current or the use of a two-step process.

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Section: Morphology Porosity and Chemical Composition Of Peo Anodic supporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

Toro

Zuleta

Correa

et al. 2020

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…The backscattered electron images (BSE) of the coatings (Figure 3c,f) show pancake-like craters (30–50 μm) and a large number of small channels of breakdowns (<5 μm); detailed information about the typical morphology of the PEO coatings can be found elsewhere [33,34,35]. According to the data collected from the optical and SEM micrographs, there is no significant influence of the alloy composition on the morphology of the top coating.…”

Section: Resultsmentioning

confidence: 99%

Wear Resistant Coatings with a High Friction Coefficient Produced by Plasma Electrolytic Oxidation of Al Alloys in Electrolytes with Basalt Mineral Powder Additions

et al. 2019

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To achieve a better performance of engineering components, modern design approaches consider the replacement of steel with lightweight metals, such as aluminum alloys. However, bare aluminum cannot satisfy requirements for surface properties in situations where continuous friction is needed. Among the various surface modification techniques, plasma electrolytic oxidation (PEO) is considered as promising for structural applications, owing to its hard and well-adhered ceramic coatings. In this work, the surfaces of two Al alloys (2024 and 6061) have been modified by PEO coating (~180 µm) reinforced with basalt minerals, in order to increase the coefficient of friction and wear resistance. A slurry electrolyte, including a silicate-alkaline solution with addition of basalt mineral powder (<5 µm) has been used. The coating composition, surface morphology, and microstructure were studied using X-ray diffraction, scanning electron, and optical microscopy. Linear reciprocating wear tests were employed for the evaluation of the friction and wear behavior. It was found that the coatings reinforced with basalt mineral showed that the wear and friction coefficients reached values 10−6–10−7 (mm3 N−1 m−1) and 0.7–0.85, correspondingly (sliding distance of 100 m). In comparison with the characteristics of resin-based materials (10−5–10−4 (mm3 N−1 m−1) and 0.3–0.5, respectively), the employment of thin inorganic frictional composites may bring considerable improvement in the thermal stability, durability, and compactness, as well as a reduction in the weight of the final product. These coatings are considered an alternative to the reinforced resin composite materials on steel used in frictional components, for example, clutch disks and braking pads. It is expected that the smaller thickness of the active frictional material (180 μm) reduces the volume of the wear products, extending the service intervals associated with filter and lubricant maintenance.

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“…Moreover, the X-ray adsorption coefficient of aluminum and oxygen is low, which make the coating unable to completely mask the underlying substrate elements [25]. γ-Alumina is one of the phases that is usually formed by PEO on Al alloys [26]. However, in the case of 7075 Al alloy coated by PEO, the significant amount of Mg and Zn as alloying elements promoted the precipitation of γ-Alumina [27,28].…”

Section: Methodsmentioning

confidence: 99%

An investigation of the characteristics of Al2O3/TiO2 PEO nanocomposite coating

Bahramian

Raeissi

Hakimizad

2015

Applied Surface Science

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Influence of the duty cycle on structural and mechanical properties of oxide layers on Al-1050 by a plasma electrolytic oxidation process

Cited by 10 publications

References 32 publications

New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

Wear Resistant Coatings with a High Friction Coefficient Produced by Plasma Electrolytic Oxidation of Al Alloys in Electrolytes with Basalt Mineral Powder Additions

An investigation of the characteristics of Al2O3/TiO2 PEO nanocomposite coating

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