Influence of coating thickness on the galvanic corrosion properties of Mg oxide in an engine coolant

Zhang, P.; Nie, Xueyuan; Northwood, Derek O.

doi:10.1016/j.surfcoat.2009.04.012

Cited by 47 publications

(11 citation statements)

References 19 publications

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“…The PEO coating thickness depends on current mode type and density, electrolyte composition and concentration and treatment time. The PEO coatings of Mg alloys are comprised of amorphous and crystalline phases such as MgO, Mg 2 SiO 4 , Mg 3 (PO 4 ) 2 or Mg 2 AlO 4 , depending on the electrolyte [32]. A recent study by Hussein et al 15 on the interactive effects of hybrid current modes on the tribological and corrosion properties of a PEO coated AM60B Mg-alloy shows that the corrosion performance is more closely related to the protective nature of the dense oxide layer at the coating-substrate interface.…”

Section: Discharge Behaviour and Coating Microstructurementioning

confidence: 99%

Processing-Microstructure Relationships in the Plasma Electrolytic Oxidation (PEO) Coating of a Magnesium Alloy

Hussein¹,

Northwood²,

Nie³

2014

MSA

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In the plasma electrolytic oxidation (PEO) coating of light metal alloys, changing the electrical parameters and electrolytic composition can change the discharge behaviour and, ultimately, the thickness, surface morphology and porosity of the coating. In the present study a combination of cathodic and anodic current pulses with suitable Ton and Toff periods were used to control the porosity and other structural defects of PEO coatings of an AM60B magnesium alloy. In order to investigate the effect of a current mode on the plasma discharge behaviour and coating microstructure during the PEO treatment of magnesium alloy, the emission intensities of six different spectral lines from the plasma species were recorded simultaneously as a function of both time and current mode using optical emission spectroscopy (OES) system. The fluctuations in signal intensities and temperature during the coating process reflect differences in location of both the discharge initiation, and discharge type. The coating surface morphology and microstructure that are obtained can be linked to the plasma discharge behavior. These results are discussed in relation to the discharge behaviour, and how such changes in discharge behaviour relate to the coating mechanisms.

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Section: Discharge Behaviour and Coating Microstructurementioning

confidence: 99%

Processing-Microstructure Relationships in the Plasma Electrolytic Oxidation (PEO) Coating of a Magnesium Alloy

Hussein¹,

Northwood²,

Nie³

2014

MSA

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“…This alloy is characterized not only by a high strength-to-weight ratio synonymous with magnesium alloys but also by relatively good properties at elevated temperatures [28]. 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].…”

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

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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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“…As a consequence, the surface properties obtained after PEO treatments are promising for industrial applications. PEO coatings have been developed for a wide range of industrial applications including the textile, gas and oil, automotive, electronics, biomedical, aerospace and metal forming industries [1][2][3][4]. Those PEO coatings are functional coatings developed to have various properties such as wear resistance, corrosion resistance and thermal protection [5].…”

Section: Introductionmentioning

confidence: 99%

Influence of process parameters on electrolytic plasma discharging behaviour and aluminum oxide coating microstructure

Hussein

Nie

Northwood

2010

Surface and Coatings Technology

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176

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Influence of coating thickness on the galvanic corrosion properties of Mg oxide in an engine coolant

Cited by 47 publications

References 19 publications

Processing-Microstructure Relationships in the Plasma Electrolytic Oxidation (PEO) Coating of a Magnesium Alloy

Processing-Microstructure Relationships in the Plasma Electrolytic Oxidation (PEO) Coating of a Magnesium Alloy

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

Influence of process parameters on electrolytic plasma discharging behaviour and aluminum oxide coating microstructure

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