The characterization of oxide based ceramic coating synthesized on Al–Si binary alloys by microarc oxidation

The Al–Si binary alloys were prepared in an atmosphere controlled furnace with the addition of 1, 2, 4, 8, 12, 16 and 32at.% Si. The alloys were coated by microarc oxidation process for 120min in a basic electrolyte containing silicate. X-Ray Diffraction, scanning electron microscope-energy dispersi...

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Bibliographic Details
Published in:Surface & coatings technology 2015-05, Vol.269, p.100-107
Main Authors: Gulec, Ali Emre, Gencer, Yucel, Tarakci, Mehmet
Format: Article
Language:English
Subjects:
Alumina
Aluminum base alloys
Al–Si alloys
Binary alloys
Binary systems
Ceramic coating
Coatings
Intermetallic compounds
Microarc oxidation (MAO)
Oxidation
Oxide based coating
Silicon
Silicon substrates
X-rays
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Summary:The Al–Si binary alloys were prepared in an atmosphere controlled furnace with the addition of 1, 2, 4, 8, 12, 16 and 32at.% Si. The alloys were coated by microarc oxidation process for 120min in a basic electrolyte containing silicate. X-Ray Diffraction, scanning electron microscope-energy dispersive X-ray spectroscopy, profilometry and Vickers microhardness tester were employed for the characterization of the coatings. The coating thickness, average microhardness and surface roughness decreased with an increase of Si content in the substrates. α-Al2O3 phase was formed in the inner region of the coating of Al–Si alloys with 1–2at.% Si while all coatings were composed of mullite and γ-Al2O3 phases along with the amorphous phase. The coating surface became smoother, the glassy regions and number of porosities with finer sizes increased with the increase of Si content in the alloys. The Si concentration was relatively higher at the most outer and inner regions of the coating and it was approximately constant in the other parts of the coatings. The entrapped volume of porosities in the coatings increased with the Si content of the substrates. •The coating thickness decreased with Si addition into substrate.•The formation α-Al2O3 was suppressed with Si content in the substrates.•The increase in amount of Si in the substrate resulted in a smoother surface.•Mullite and γ-Al2O3 phases existed on all coatings.•α-Al2O3 phase was only detected on coating of alloys with 1–2at.% Si.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2014.12.031