A Novel Self-Adaptive Control Method for Plasma Electrolytic Oxidation Processing of Aluminum Alloys

Yang, Kai; Zeng, Jiaquan; Huang, Haisong; Chen, Jiadui; Biao, Cao

doi:10.3390/ma12172744

Cited by 11 publications

(6 citation statements)

References 32 publications

(65 reference statements)

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“…In PEO, a target metal is subjected to a high voltage which leads to the discharge appearance on the surface with the extremely high temperature and pressure that both provide oxidation of the surface. Usually, PEO treatment is conducted in an aqueous electrolyte made of silicates, phosphates, aluminates, fluorides, and other [7][8][9][10][11][12]. Recently, we have showed a possible implementation of the electrolyte of the molten salt in the PEO process [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Ceramic Coating on Al7075 Alloy by Plasma Electrolytic Oxidation in Molten Salt

2020

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The fabrication of a ceramic coating on the metallic substrate is usually applied to achieve the improved performance of the material. Plasma electrolytic oxidation (PEO) is one of the most promising methods to reach this performance, mostly wear and corrosion resistance. Traditional PEO is carried out in an aqueous electrolyte. However, the current work showed the fabrication and characterization of a ceramic coating using PEO in molten salt which was used to avoid disadvantages in system heating-up and the formation of undesired elements in the coating. Aluminum 7075 alloy was subjected to the surface treatment using PEO in molten nitrate salt. Various current frequencies were applied in the process. Coating investigations revealed its surface porous structure and the presence of two oxide layers, α-Al2O3 and γ-Al2O3. Microhardness measurements and chemical and phase examinations confirmed these results. Potentiodynamic polarization tests and electrochemical impedance spectroscopy revealed the greater corrosion resistance for the coated alloy. Moreover, the corrosion resistance was increased with the current frequency of the PEO process.

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Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Ceramic Coating on Al7075 Alloy by Plasma Electrolytic Oxidation in Molten Salt

2020

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“…[11,14,15] The experimental conditions employed in the PEO treatment allow the control of the morphology and microstructure of the oxide film, influencing other properties. [15][16][17] Additionally, the PEO condition can be obtained by different electrical stimulation, such as galvanostatic or potentiostatic (DC PEO), [18][19][20] alternate current, [21,22] pulsed potential/ current, [23,24] and hybrid [25,26] modes. The galvanostatic DC mode is handy for monitoring the stages of the oxide growth and mapping the system to comprehend its electrochemical behavior.…”

Section: Introductionmentioning

confidence: 99%

Alumina Coatings Containing Niobium Pentoxide Polymorphs Prepared by Plasma Electrolytic Oxidation of Aluminum

et al. 2023

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“…As an alternative approach to the tailored coatings, a few closed loop methods have been reported. Yang et al , suggested pulse shape monitoring to avoid current spike and associated detrimental discharge appearance. Hermanns et al applied in situ image analysis of microdischarges acting on the sample surface to prevent large destructive discharges generation by automatic narrowing of the pulse width.…”

Section: Introductionmentioning

confidence: 99%

Relaxation Kinetics of Plasma Electrolytic Oxidation Coated Al Electrode: Insight into the Role of Negative Current

2020

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Plasma electrolytic oxidation (PEO) is an advanced coating process based on high-voltage anodizing. Notwithstanding the anodic nature of the PEO process, it is known that negative polarization leads to synergetic effects in oxide formation efficiency and characteristics of resulting coatings. In this work, we used dynamic anodic voltammograms derived from polarization signal, combining working and diagnostic segments to evaluate in real time the effects of negative polarization on the formation of PEO on the coating on Al in the bipolar regime with a frequency of 50 Hz and a negative-to-positive charge ratio of 1.3. It was found that the hysteresis between ascending and descending branches of the voltammogram can be both caused by prior cathodic polarization and spontaneously generated under unpolarized conditions. This indicated the existence of a quasi-equilibrium in the chemical state of the coating material, which could be perturbed by the external bipolar polarization. The characteristic relaxation time for this system was found to be 40–370 ms. The quasi-equilibrium was attributed to a reversible hydration/dehydration reaction taking place in the active zone of anodic alumina layer (degree of hydration: 10–40%). Coating response analysis via kinetic hydration model allowed both explanations to be provided to a number of previous experimental observations and practical recommendations to be made for the design of efficient electrical regimes for intelligent PEO processes. The latter includes recommendations on avoiding long pauses during negative to positive switching.

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A Novel Self-Adaptive Control Method for Plasma Electrolytic Oxidation Processing of Aluminum Alloys

Cited by 11 publications

References 32 publications

Fabrication and Characterization of Ceramic Coating on Al7075 Alloy by Plasma Electrolytic Oxidation in Molten Salt

Fabrication and Characterization of Ceramic Coating on Al7075 Alloy by Plasma Electrolytic Oxidation in Molten Salt

Alumina Coatings Containing Niobium Pentoxide Polymorphs Prepared by Plasma Electrolytic Oxidation of Aluminum

Relaxation Kinetics of Plasma Electrolytic Oxidation Coated Al Electrode: Insight into the Role of Negative Current

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