Fabrication of n-SiO₂ Reinforced Al₂O₃ Composite Coatings on 7A52 Aluminium Alloy by Micro-Arc Oxidation

Abstract:

Micro-arc oxidation (MAO) is an effective approach to improve the properties of aluminium and its alloys by forming ceramic coatings on the surface. However, the oxide layers often have a porous surface structure, which limits their mechanical properties. In order to enhance the properties of the layers produced by micro-arc oxidation, SiO2 nanoparticles reinforced Al2O3 composite coatings were produced on 7A52 aluminium alloy by adding SiO2 nanoparticles into the electrolyte. With the addition of SiO2 nanoparticles in the electrolyte, the formation rate of Al2O3 coating enhanced considerably and the current density through the sample surface became much higher than that without SiO2 at the same voltage. The coatings were investigated with X-ray fluorescence spectrometry (XRF), Scanning electron microscopy (SEM), Vickers hardness test, and reciprocating friction and wear test. Compared with the Al2O3 coatings without SiO2 nanoparticles, the n-SiO2 reinforced Al2O3 composite coatings are much denser and harder, and the wear resistance is also improved significantly. The improvement can be attributed to the enhancement of the surface structure and morphology of the n- SiO2 reinforced Al2O3 composite coatings.

• Periodical: Advanced Materials Research (Volumes 97-101)
• Pages: 1463-1466
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.97-101.1463
• Online since: March 2010
• Authors: Shi Ning Ma, Xiang Bo Suo, Ji Qiu
• Keywords: Composite Coating, Micro-Arc Oxidation (MAO), SiO₂ Nanoparticle, Surface Properties

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5 1.

[1] 5 2.

[2] 5 3 0 5 10 15 20 25 30 Time(min) Friction coefficient 7A52 aluminum alloy n-SiO2 reinforced composite(45µm) MAO coating without silica nanoparticles(45µm).

[2] 70E-01.

[2] 89E-03.

[1] 87E-03.

[1] 00E-03.

[1] 00E-02.

[1] 00E-01.

[1] 00E+00 a b c Sample Number weight loss wear rate(mg/min) Fig. 5 Friction coefficients as a function of sliding time Fig. 6 Weight loss wear rate of (a)7A52 Al alloy (b) n-SiO2 reinforced composite coating (c)coating without n-SiO2.