Development of anodic coatings on aluminium under sparking conditions in silicate electrolyte

Monfort, F.; Berkani, A.; Matykina, E.; Skeldon, P.; Thompson, G.E.; Habazaki, H.; Shimizu, K.

doi:10.1016/j.corsci.2006.05.046

Cited by 159 publications

(55 citation statements)

References 35 publications

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“…5). The results suggest that the silicon content is higher in the outermost parts of the coating, which is consistent with the findings of other authors [46][47][48][49]. The coatings grown onto the samples anodised at voltages below the dielectric breakdown potential of the oxide layer were of a barrier-type and covered the entire surface of the niobium metal tightly.…”

Section: Resultssupporting

confidence: 82%

“…The analysis of the XRD patterns of the samples that were subjected to anodisation performed at 400 V in various baths showed that the amount of the Nb-containing crystalline phases did not markedly changed with the K 2 SiO 3 concentration. The XRD patterns of the niobium samples that have been subjected to PEO (under voltage of 400 V) show a characteristic halo between 2θ equal to 15°and 30°, which was also recognised by other researchers [46,47,49,51] to be a signal of amorphous silica phase. This effect is the most pronounced in the case of the Nb-ANO-1.0-400 (Fig.…”

Section: Resultsmentioning

confidence: 81%

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Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Sowa

Kazek-Kęsik

Krząkała

et al. 2013

J Solid State Electrochem

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Herein, a study of the plasma electrolytic oxidation (PEO) of niobium in an anodising bath composed of potassium silicate (K 2 SiO 3 ) and potassium hydroxide (KOH) is reported. The effects of the K 2 SiO 3 concentration in the bath and the process voltage on the characteristics of the obtained oxide layers were assessed. Compact, barrier-type oxide layers were obtained when the process voltage did not exceed the breakdown potential of the oxide layer. When this threshold was breached, the morphology of the oxide layer changed markedly, which is typical of PEO. A significant amount of silicon, in the form of amorphous silica, was incorporated into the oxide coatings under these conditions compared with the amount obtained with conventional anodising. This surface modification technique led to an improvement in the corrosion resistance of niobium in Ringer's solution, regardless of the imposed process conditions.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 81%

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Sowa

Kazek-Kęsik

Krząkała

et al. 2013

J Solid State Electrochem

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“…Relatively thin coating is developed in the acid electrolyte, compared with that in the alkaline electrolyte. It has been reported that the rapid coating growth occurs at sites of dielectric breakdown [35,36]. Thus, the relatively thin coating in the acid electrolyte is associated with the relatively weak micro-discharges during PEO processing.…”

Section: Characterization Of Coatingsmentioning

confidence: 99%

Two-step plasma electrolytic oxidation of Ti–15V–3Al–3Cr–3Sn for wear-resistant and adhesive coating

Tsunekawa

Aoki

Habazaki

2011

Surface and Coatings Technology

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Ti-15V-3Al-3Cr-3Sn (Ti-15-3) is one of the important practical titanium alloys with high cold deformability and high mechanical strength, but its wear resistance is poor. This paper reports the formation of wear-resistant and adhesive ceramic coatings on Ti-15-3 by two-step plasma electrolytic oxidation (PEO). The PEO of Ti-15-3 has been carried out first in alkaline aluminate electrolyte to form a wear-resistant oxide layer and then in acid electrolyte containing both phosphoric acid and sulphuric acid to improve adhesion of the coating. The coating formed in the alkaline aluminate electrolyte is more than 10 m thick, and highly crystalline. The main phase is Al 2 TiO 5 .This coating shows high wear resistance, but is not adherent to substrate due to the development of a number of voids and pores in the oxide layer close to the substrate. A new oxide layer with amorphous structure is formed next to the substrate in the subsequent PEO in the acid electrolyte, during which the voids are filled with a new 2 oxide formed in the acid electrolyte, reducing the porosity. As a consequence, the adhesion of the coating is markedly improved without deteriorating the high wear resistance.

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“…The explanation for this may be related to the fact that PEO coatings contain high levels of surface-connected porosity, reported by Curran and Clyne [4] as being~15-20%. Also, TEM observations by Nie et al [22] and Monfort et al [23] on Al, and Arrabal et al [7] on Mg, included reports of a thin, and apparently continuous layer, of amorphous material at the boundary with the substrate. These studies all reported that this layer has a thickness in the range from a few hundred nm to 1 μm.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of discharge events during plasma electrolytic oxidation

Dunleavy

Golosnoy

Curran

et al. 2009

Surface and Coatings Technology

325

169

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A study has been made of the electrical characteristics and optical emission spectra exhibited when discharge events take place during plasma electrolytic oxidation processing. Both conventional and small area experimental arrangements have been employed, allowing detailed measurement of durations, and temporal distributions, as well as such characteristics as charge transfer, and power. Individual discharges are of short duration, typically tens to hundreds of microseconds, but there is a strong tendency for them to occur in cascades that commonly last between several ms and several tens of ms. The composition, temperature and electron density of the plasma formed during PEO processing are inferred from characteristics of the emission spectra. This confirms that there are two distinct regions of plasma; a lower density peripheral region at~3500 K, and a higher density core at 16,000 ± 3500 K. The implications of these results are considered in terms of the interpretation of different types of experimental measurement, and attention is also briefly given to how such behaviour might relate to the mechanisms of growth.

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Development of anodic coatings on aluminium under sparking conditions in silicate electrolyte

Cited by 159 publications

References 35 publications

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Two-step plasma electrolytic oxidation of Ti–15V–3Al–3Cr–3Sn for wear-resistant and adhesive coating

Characterisation of discharge events during plasma electrolytic oxidation

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