Application of Voltage Pulse Transient Analysis during Plasma Electrolytic Oxidation for Assessment of Characteristics and Corrosion Behaviour of Ca- and P-containing Coatings on Magnesium

Gao, Yonghao; Yerokhin, Aleksey; Парфенов, Е.В.; Matthews, A.

doi:10.1016/j.electacta.2014.10.063

Cited by 87 publications

(48 citation statements)

References 48 publications

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“…Generally, the voltage response during the PEO treatment is similar to that reported previously [38]. According to the voltage transients, the PEO processes can be characterized in three different stages.…”

Section: Corrosion Evaluationmentioning

confidence: 78%

Self-healing plasma electrolytic oxidation coatings doped with benzotriazole loaded halloysite nanotubes on AM50 magnesium alloy

et al. 2016

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0 200 -150 0 50 Z (kcm 2 ) Z (kcm 2 )2 Research Highlights  Simple single-step PEO process for production of self-healing coatings on Mg  Benzotriazole loaded halloysite nanotubes incorporated in PEO coatings on Mg  The nanotubes increased mechanical properties of PEO coatings  pH increase at corrosion sites promoted BTA-mediated nucleation of Mg(OH)2  Dense Mg(OH)2 film formed on corrosion sites inhibited pitting corrosion Abstract:Halloysite nanotubes (HNT) and benzotriazole (BTA) loaded HNT were added to a silicatebased electrolyte to produce PEO coatings on AM50 alloy. The coatings were characterised by SEM, EDX and XRD methods. Corrosion behaviour in 3.5 wt.% NaCl was studied by EIS and PDP scans. The HNT increased coating scratch resistance greater than BTA-HNT, although the latter enhanced corrosion resistance due to a self-healing effect. This was triggered by a dense Mg(OH)2 film being formed on corrosion sites following partial coating degradation, preventing pitting corrosion. The single-step process for producing self-healing PEO coatings has good potential in corrosion protection of Mg.

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Section: Corrosion Evaluationmentioning

confidence: 78%

Self-healing plasma electrolytic oxidation coatings doped with benzotriazole loaded halloysite nanotubes on AM50 magnesium alloy

et al. 2016

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“…5. In principle, the corrosion rate P EIS could be calculated according to King [40] and Gao [45] et al, by determining the polarization resistance (R polar ) first. Briefly, the R polar was obtained by extrapolating the EIS to the frequency that is sufficiently low (f ≈ 0).…”

Section: Transient Electrochemical Corrosion Behaviormentioning

confidence: 99%

Comparative corrosion behavior of Zn with Fe and Mg in the course of immersion degradation in phosphate buffered saline

et al. 2016

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“…On these issues, researchers are fully aware of the critical need for a tool to quantify the plasma state in an aqueous electrolyte. Optical, electrical, and acoustic signals have been studied for that purpose [54,[61][62][63][64][65]. Current OES technique has achieved more success than the other two, and is on its way to being an in situ diagnostic tool [66][67][68][69].…”

Section: Plasma State In Electron Temperaturementioning

confidence: 99%

Review of the Soft Sparking Issues in Plasma Electrolytic Oxidation

Tsai

Chou

2018

Metals

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Abstract:A dense inner layer is highly valued among the surface coatings created through plasma electrolytic oxidation (PEO) treatment, because the PEO coating has been troubled by inherent porosity since its conception. To produce the favored structure, a proven technique is to prompt a soft sparking transition, which involves a sudden decrease in light and acoustic emissions, and a drop in anodic voltage under controlled current mode. Typically these phenomena occur in an electrolyte of sodium silicate and potassium hydroxide, when an Al-based sample is oxidized with an AC or DC (alternating or direct current) pulse current preset with the cathodic current exceeding the anodic counterpart. The dense inner layer feature is pronounced if a sufficient amount of oxide has been amassed on the surface before the transition begins. Tremendous efforts have been devoted to understand soft sparking at the metal-oxide-electrolyte interface. Studies on aluminum alloys reveal that the dense inner layer requires plasma softening to avoid discharge damages while maintaining a sufficient growth rate, a porous top layer to retain heat for sintering the amassed oxide, and proper timing to initiate the transition and end the surface processing after transition. Despite our understanding, efforts to replicate this structural feature in Mg-and Ti-based alloys have not been very successful. The soft sparking phenomena can be reproduced, but the acquired structures are inferior to those on aluminum alloys. An analogous quality of the dense inner layer is only achieved on Mg-and Ti-based alloys with aluminate anion in the electrolytic solution and a suitable cathodic current. These facts point out that the current soft sparking knowledge on Mg-and Ti-based alloys is insufficient. The superior inner layer on the two alloys still relies on rectification and densification of aluminum oxide.

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Application of Voltage Pulse Transient Analysis during Plasma Electrolytic Oxidation for Assessment of Characteristics and Corrosion Behaviour of Ca- and P-containing Coatings on Magnesium

Cited by 87 publications

References 48 publications

Self-healing plasma electrolytic oxidation coatings doped with benzotriazole loaded halloysite nanotubes on AM50 magnesium alloy

Self-healing plasma electrolytic oxidation coatings doped with benzotriazole loaded halloysite nanotubes on AM50 magnesium alloy

Comparative corrosion behavior of Zn with Fe and Mg in the course of immersion degradation in phosphate buffered saline

Review of the Soft Sparking Issues in Plasma Electrolytic Oxidation

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