Correlation between KOH concentration and surface properties of AZ91 magnesium alloy coated by plasma electrolytic oxidation

Ko, Young Gun; Namgung, Seung; Shin, Dong Hyuk

doi:10.1016/j.surfcoat.2010.09.055

Cited by 124 publications

(45 citation statements)

References 48 publications

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“…In direct cur rent sources, a double wave detection scheme is typi cally used and enables one to set either galvanostatic or potentiostatic current conditions. Pulsed current sources make it possible to interrupt the process repeatedly and, hence, control the arc duration [42][43][44]. However, pulsed current can cause an additional polarization of the electrode surface due to the cre ation of a charged double layer.…”

Section: Technique Of Electrolytic Processesmentioning

confidence: 99%

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Electrolytic plasma processing for plating coatings and treating metals and alloys

Pogrebnyak

Kaverina

Кылышканов

2014

Prot Met Phys Chem Surf

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Abstract-A review of the methods of electrochemical treatment classified as plasma electrolysis is given. Special attention is paid to the physicochemical processes that proceed in electrolytes and the techniques of surface modification and application of protective coatings. The results of investigation of such coatings and surfaces upon electrolytic plasma processing illustrate the efficiency and effectiveness of the method. Being an efficient technique of the surface treatment, which involves both the surface cleaning and plating the coat ing, the plasma electrolytic method is being rapidly developed and adapted for commercial use at present.

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Section: Technique Of Electrolytic Processesmentioning

confidence: 99%

“…Therefore, the formation of com pounds on the anode is also often accompanied by oxi dation and the oxide layer is often present on the surfaces of, e.g., carbide, nitride, or boride layers. In order to eliminate surface oxidation, one can use the cathodic polarization technique [42][43][44].…”

Section: Diffusion and Plasma Chemical Reactions Cataphoretic Effectsmentioning

confidence: 99%

Electrolytic plasma processing for plating coatings and treating metals and alloys

Pogrebnyak

Kaverina

Кылышканов

2014

Prot Met Phys Chem Surf

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“…The PEO method can be used to form a thick, hard and adherent ceramic coating on the surface of Mg alloys as well as the valve metals (Al and Ti) and their alloys [14]. Coating surface morphology, structure and corrosion resistance are affected by many parameters including electrolyte composition [15][16][17][18], substrate material [19], and the electrical parameters, mainly current mode and current density [9,20]. Different current modes have been utilized in the PEO treatment including, DC, AC, unipolar and bipolar current modes [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

The effect of current mode and discharge type on the corrosion resistance of plasma electrolytic oxidation (PEO) coated magnesium alloy AJ62

Hussein

Zhang

Nie

et al. 2011

Surface and Coatings Technology

210

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Magnesium alloys are increasingly being used as lightweight materials in the automotive, defense, electronics, biomaterial and aerospace industries. However, their inherently poor corrosion and wear resistance have, so far, limited their application. Plasma electrolytic oxidation (PEO) in an environmentally friendly aluminates electrolyte has been used to produce oxide coatings with thicknesses of~80 μm on an AJ62 magnesium alloy. Optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285 nm-800 nm) was employed to characterize the PEO plasma. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the coated materials, and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution were used to determine the corrosion behavior. It was found that the plasma discharge behavior significantly influenced the microstructure and the morphology of the oxide coatings and, hence the corrosion resistance. The corrosion resistance of the coated alloy was increased by changing the current mode from unipolar to bipolar, where the strong plasma discharges had been reduced or eliminated.

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“…During the process, a high voltage between the anode and the sample was generated, inducing micro-discharges on the specimen surface and converting the alloy surface into a hard oxide layer. PEO layers on Mg alloys can be usually divided into two or three regions, according to the operative treatment conditions: (i) a thin barrier layer (generally hundreds of nanometres) at the interface with the base material; (ii) a compact intermediate inner layer, with a small amount of porosities and cavities; (iii) an outer region with a high number of pores and crater density [37][38][39].…”

Section: Microstructure Of the Peo-treated Alloymentioning

confidence: 99%

Fatigue Behavior of the Rare Earth Rich EV31A Mg Alloy: Influence of Plasma Electrolytic Oxidation

Ceschini¹,

Morri²,

Angelini³

et al. 2017

Preprint

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Rare earth rich magnesium alloys are used in aerospace and automotive fields because of their high specific strength and good castability. However, due to their low corrosion resistance, protective surface treatments, such as conversion coating or electroless plating are necessary, when they have to be used in humid or corrosive environments. The present study was aimed to evaluate the effect of Plasma Electrolytic Oxidation (PEO) and different surface roughness on the rotating bending fatigue of an innovative Mg alloy, with a high content of Nd (up to 3.1 wt%) and Gd (up to 1.7 wt %). Fatigue tests revealed a 15% decrease in the fatigue strength of the PEO treated alloy with respect to the bare alloy, probably due to the residual tensile stresses induced by the treatment. The effect of surface roughness on the bare alloy was, instead, negligible. The mechanisms of crack initiation were similar in the untreated and PEO treated alloy, with crack nucleation sites located in correspondence of large facets of the cleavage planes.

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Correlation between KOH concentration and surface properties of AZ91 magnesium alloy coated by plasma electrolytic oxidation

Cited by 124 publications

References 48 publications

Electrolytic plasma processing for plating coatings and treating metals and alloys

Electrolytic plasma processing for plating coatings and treating metals and alloys

The effect of current mode and discharge type on the corrosion resistance of plasma electrolytic oxidation (PEO) coated magnesium alloy AJ62

Fatigue Behavior of the Rare Earth Rich EV31A Mg Alloy: Influence of Plasma Electrolytic Oxidation

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