TEM analysis and tribological properties of Plasma Electrolytic Oxidation (PEO) coatings on a magnesium engine AJ62 alloy

Zhang, P.; Nie, Xueyuan; Hu, Henry; Liu, Y.

doi:10.1016/j.surfcoat.2010.10.015

Cited by 45 publications

(13 citation statements)

References 25 publications

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“…A transmission electron microscopy (TEM) study has also shown these phases existed in a PEO coating on AJ62 prepared using a unipolar mode [30]. Changing the current mode from unipolar to bipolar current mode did not alter the phases formed except for slight changes in the oxide peak intensity.…”

Section: S4 (A)mentioning

confidence: 97%

“…AJ62 is the only Mg-Al alloy thus far to have been used in the mass production of an automotive power train crankcase [29]. The PEO process has been investigated as a way of improving the wear and corrosion resistance of this Mg alloy [30][31]. An attempt in this paper was made to understand the effect of current modes on the plasma discharge behavior and plasma temperature which were believed to have a significant effect on morphology and microstructures of the resultant oxide coatings for the Mg alloy.…”

Section: Introductionmentioning

confidence: 99%

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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

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212

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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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Section: S4 (A)mentioning

confidence: 97%

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

Self Cite

212

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show abstract

“…5 It can produce relatively thick, dense, hard nanostructured oxide coatings which effectively improve the resistances of the substrates. [6][7][8][9] However, the coatings can also influence to some extent the heat transfer between the coated components and the surroundings, especially in the situations where heat transfer must be considered. For instance, magnesium oxide coatings deposited on the cylinder bores can effectively enhance the wear resistance of a magnesium * Authors to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Thermal Conductivities of Nanostructured Magnesium Oxide Coatings Deposited on Magnesium Alloys by Plasma Electrolytic Oxidation

Shen¹,

Nie²,

Hu³

2014

j nanosci nanotechnol

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The resistances of magnesium alloys to wear, friction and corrosion can be effectively improved by depositing coatings on their surfaces. However, the coatings can also reduce the heat transfer from the coated components to the surroundings (e.g., coated cylinder bores for internal combustion of engine blocks). In this paper, nanostructured magnesium oxides were produced by plasma electrolytic oxidation (PEO) process on the magnesium alloy AJ62 under different current densities. The guarded comparative heat flow method was adopted to measure the thermal conductivities of such coatings which possess gradient nanoscale grain sizes. The aim of the paper is to explore how the current density in the PEO process affects the thermal conductivity of the nanostructured magnesium coatings. The experimental results show that, as the current density rises from 4 to 20 A/mm2, the thermal conductivity has a slight increase from 0.94 to 1.21 W/m x K, which is significantly smaller than that of the corresponding bulk magnesium oxide materials (29.4 W/m x K). This mostly attributed to the variation of the nanoscale grain sizes of the PEO coatings.

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“…In answer to this, coating technology has been considered to be an effective means of controlling and reducing corrosion rates, such as organic coatings [2], microarc oxidation (MAO) [8], high velocity oxy-fuel thermal spray [9] and physical vapor deposition [10]. Among them, MAO has been most commercially used on Mg and Mg alloys [11][12][13]. This is due to low cost, good adhesion, wide range of coating thickness, higher stability and corrosion resistance provided by MAO [14].…”

Section: Introductionmentioning

confidence: 99%

Effect of chloride ion level on the corrosion performance of MAO modified AZ31 alloy in NaCl solutions

Cai

Guo

et al. 2013

Materials & Design

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TEM analysis and tribological properties of Plasma Electrolytic Oxidation (PEO) coatings on a magnesium engine AJ62 alloy

Cited by 45 publications

References 25 publications

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

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

Thermal Conductivities of Nanostructured Magnesium Oxide Coatings Deposited on Magnesium Alloys by Plasma Electrolytic Oxidation

Effect of chloride ion level on the corrosion performance of MAO modified AZ31 alloy in NaCl solutions

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