Hard Anodic Coating of Magnesium Alloys, Alkaline Type, High Voltage

Effect of V2O5 additive in silicate-containing electrolyte on AZ91D magnesium alloys treated by micro-arc oxidation (MAO) technology under different loading voltages was investigated. The results showed that vanadium was well up-taken into the coating chemically. Moreover, a new phase of MgV2O4 with spinel structure was obtained in MAO coatings due to V2O5 added into the electrolyte. The MgV2O4 phase was responsible for the coatings exhibiting brown color and also was beneficial to improving the anti-corrosion property. In spotting tests, the corrosion resistances of coatings prepared under the high voltage are about 6–9 times higher than those of the low voltage because of the thicker coatings of the former. In potentiodynamic polarization tests, the coatings’ corrosion resistances were improved with the addition of V2O5, which was more significant under the low voltage than that under the high voltage. When the concentration of V2O5 was 0.2 g/L, the corrosion current density of the coating was the lowest, which means that the coating’s corrosion resistance under the low voltage is the best. Hence, it is necessary to carry out targeted design of the coating’s microstructure according to the different applications.

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Anodic coating of magnesium alloys

Journal of Research of the National Bureau of Standards ◽

10.6028/jres.018.048 ◽

1937 ◽

Vol 18 (1) ◽

pp. 83 ◽

Cited By ~ 1

Author(s):

R.W. Buzzard ◽

J.H. Wilson

Keyword(s):

Magnesium Alloys ◽

Anodic Coating

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High Voltage Electron Microscopy of Ion-Milled Dental Enamel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050317 ◽

1974 ◽

Vol 32 ◽

pp. 60-61

Author(s):

L. D. Ackerman ◽

S. H. Y. Wei

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Third Molar ◽

Polarized Light ◽

Dental Enamel ◽

Longitudinal Section ◽

Ion Milling ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

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