Microstructure and elevated temperature tribological behavior of TiO 2 /Al 2 O 3 composite ceramic coating formed by microarc oxidation of Ti6Al4V alloy

A nanostructured TiO2 dominated ceramic coating was fabricated on Ti6Al4V by microarc oxidation (MAO). The coating with about 30 μm thickness is porous in the outer layer and compact in the inner layer, mainly composed of rutile and a small amount of anatase TiO2, both in nano grain structure. The hardness and elastic modulus of the compact layer in the coating are about 8.5 GPa and 87.4 GPa. The adhesion strength is about 70MPa. The friction coefficient of the polished coating sliding against GCr15 steel is as low as 0.2, which is clearly superior to that of the unpolished one. This is attributed to the low surface roughness. However, the oxidation wear mechanism occurring at the later stage of wear tests leads to a gradual increase of friction coefficient.

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In situ formation of Al2O3–SiO2–SnO2 composite ceramic coating by microarc oxidation on Al–20%Sn alloy

Applied Surface Science ◽

10.1016/j.apsusc.2009.12.050 ◽

2010 ◽

Vol 256 (11) ◽

pp. 3443-3447 ◽

Cited By ~ 9

Author(s):

Zhijiang Wang ◽

Lina Wu ◽

Yulin Qi ◽

Zhaohua Jiang

Keyword(s):

Ceramic Coating ◽

Microarc Oxidation ◽

Composite Ceramic ◽

In Situ Formation

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Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

Journal of Ceramics ◽

10.1155/2013/350931 ◽

2013 ◽

Vol 2013 ◽

pp. 1-14 ◽

Cited By ~ 8

Author(s):

Mohannad M. S. Al Bosta ◽

Keng-Jeng Ma ◽

Hsi-Hsin Chien

Keyword(s):

Surface Roughness ◽

Current Density ◽

Ceramic Coating ◽

Microarc Oxidation ◽

Ceramic Coatings ◽

Anodic Current Density ◽

Ceramic Surface ◽

Anodic Current ◽

Alumina Phase ◽

Current Densities

High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm), while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm) to higher but approximately the same emissivities.

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