Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

Journal Article · Thu Dec 15 00:00:00 EST 2011 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2011.10.010· OSTI ID:22066400

Tarakci, Mehmet

The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

• OSTI ID: 22066400
• Journal Information: Materials Characterization, Vol. 62, Issue 12; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
BINARY ALLOY SYSTEMS
CERAMICS
INTERMETALLIC COMPOUNDS
LAYERS
MAGNESIUM
MICROHARDNESS
MULLITE
OXIDATION
PLASMA
POROUS MATERIALS
POTASSIUM HYDROXIDES
PRECIPITATION
ROUGHNESS
SCANNING ELECTRON MICROSCOPY
SODIUM SILICATES
SUBSTRATES
SURFACES
X-RAY DIFFRACTION