Growth behavior and insulation property of the oxide layer during micro-arc oxidation of aluminium in “soft” regime condition

Song, Shiyu; Chen, Bin; Li, Hongtao; Liu, Cancan; Yang, Bo; Fuente, Germán F. de la

doi:10.1007/s10853-023-08470-y

Cited by 7 publications

(3 citation statements)

References 40 publications

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“…The mechanism was investigated, and it was found that the soft sparking condition is favorable for filling the cavities of a coating and that the filled cavities can effectively reduce the porosity of the coating, thus enhancing the adhesion between the substrate and the PEO coating. This has been well established in the studies of Song et al [8] and Qian et al [4]. In addition, Cheng et al [14] showed that the abrasion resistance of PEO coatings is related to the holes in the coatings.…”

Section: Introductionmentioning

confidence: 70%

“…Interestingly, when the cathodic current is higher than the anodic current, a unique discharge phenomenon called a “soft spark” is generated during the plasma electrolytic oxidation of aluminum alloys. It has been proved by Qian et al [ 4 ] and Song et al [ 8 ] that the relative content of α-Al 2 O 3 in the PEO process of aluminum alloys increases with the prolongation of the soft spark discharge time, and the mechanism of soft spark formation on the surface of aluminum alloys has been further investigated by Martin et al [ 9 , 10 , 11 , 12 ] and Tjiang et al [ 13 ]. The mechanism was investigated, and it was found that the soft sparking condition is favorable for filling the cavities of a coating and that the filled cavities can effectively reduce the porosity of the coating, thus enhancing the adhesion between the substrate and the PEO coating.…”

Section: Introductionmentioning

confidence: 99%

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Study of Coating Growth Direction of 6061 Aluminum Alloy in Soft Spark Discharge of Plasma Electrolytic Oxidation

Wang,

Yang,

Liu

et al. 2024

Materials

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Conventional plasma electrolytic oxidation treatments produce oxide coatings with micron-scale discharge pores, resulting in insulation and wear and corrosion resistance far below that expected of highly dense Al2O3 coatings. The introduction of cathodic polarization during the plasma electrolytic oxidation process, especially when the applied cathode-to-anode current ratio (Rpn) is greater than 1, triggers a unique plasma discharge phenomenon known as “soft sparking”. The soft spark discharge mode significantly improves the densification of the anode ceramic layer and facilitates the formation of the high-temperature α-Al2O3 phase within the coating. Although the soft spark discharge phenomenon has been known for a long time, the growth behavior of the coating under its discharge mode still needs to be studied and improved. In this paper, the growth behavior of the coating before and after soft spark discharge is investigated with the help of the micro-morphology, phase composition and element distribution of a homemade fixture. The results show that the ceramic layer grows mainly along the oxide–electrolyte direction before the soft spark discharge transformation; after the soft spark discharge, the ceramic layer grows along the oxide–substrate direction. It was also unexpectedly found that, under soft spark discharge, the silicon element only exists on the outside of the coating, which is caused by the large size and slow migration of SiO32−, which can only enter the ceramic layer and participate in the reaction through the discharge channel generated by the strong discharge. In addition, it was also found that the relative phase content of α-Al2O3 in the coating increased from 0.487 to 0.634 after 10 min of rotary spark discharge, which is an increase of 30.2% compared with that before the soft spark discharge transition. On the other hand, the relative phase content of α-Al2O3 in the coating decreased from 0.487 to 0.313 after 20 min of transfer spark discharge, which was a 55.6% decrease compared to that before the soft spark discharge transformation.

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Section: Introductionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Study of Coating Growth Direction of 6061 Aluminum Alloy in Soft Spark Discharge of Plasma Electrolytic Oxidation

Wang,

Yang,

Liu

et al. 2024

Materials

Self Cite

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“…It should be noted that the diffraction peak of Al deviates from the standard position of the Al peak and shifts slightly to the right [37,42,43]. The occurrence of this peak shift phenomenon indicates a distortion in the lattice constant of the Al crystal during the processes of hot-dip coating and micro-arc oxidation [44][45][46]. This phenomenon may be related to the presence of residual stresses, or compounds such as Al 2 O 3 , ZrO 2 , or SiO 2 .…”

Section: Phase Analysis Of Micro-arc Oxidation Ceramic Coatingsmentioning

confidence: 95%

Insight into Microstructure Evolution and Corrosion Mechanisms of K2ZrF6/Al2O3-Doped Hot-Dip Aluminum/Micro-Arc Oxidation Coatings

Wang,

Peng,

Yang

et al. 2023

Coatings

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In this study, we investigated the impact of K2ZrF6/Al2O3 composite additives on the microstructure evolution and corrosion behavior of ceramic coatings formed through micro-arc oxidation (MAO) treatment on hot-dip aluminum-coated 316L stainless steel surfaces. Our findings revealed the successful preparation of micro-arc oxidation ceramic coatings, presenting a dual-layer structure consisting of a porous micro-arc oxidation ceramic outer layer and a relatively dense/thick hot-dip aluminum inner layer. The incorporation of K2ZrF6/Al2O3 composite additives induced a self-sealing effect on the ceramic coating surface. Optimal coating performance was achieved with a composite additive concentration of 7.5 g/L, resulting in remarkable improvements not only in thickness, hardness, and surface smoothness but also in corrosion resistance. This research introduces a pioneering investigation of K2ZrF6/Al2O3 composite additives in the context of micro-arc oxidation technology, offering fresh perspectives and methodologies for the development of highly corrosion-resistant materials.

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Effect of oxide layer on the electrochemical corrosion behavior of a Ni-based superalloy in 3.5 wt% NaCl

Wang

Yang

et al. 2023

International Journal of Electrochemical Science

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Growth behavior and insulation property of the oxide layer during micro-arc oxidation of aluminium in “soft” regime condition

Cited by 7 publications

References 40 publications

Study of Coating Growth Direction of 6061 Aluminum Alloy in Soft Spark Discharge of Plasma Electrolytic Oxidation

Study of Coating Growth Direction of 6061 Aluminum Alloy in Soft Spark Discharge of Plasma Electrolytic Oxidation

Insight into Microstructure Evolution and Corrosion Mechanisms of K2ZrF6/Al2O3-Doped Hot-Dip Aluminum/Micro-Arc Oxidation Coatings

Effect of oxide layer on the electrochemical corrosion behavior of a Ni-based superalloy in 3.5 wt% NaCl

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