Formation of a compact oxide layer on AZ91D magnesium alloy by microarc oxidation via addition of cerium chloride into the MAO electrolyte

2011 ◽  
Vol 8 (6) ◽  
pp. 765-771 ◽  
Author(s):  
M. Laleh ◽  
Farzad Kargar ◽  
A. Sabour Rouhaghdam
Keyword(s):  
Magnesium Alloy ◽  
Oxide Layer ◽  
Microarc Oxidation ◽  
Cerium Chloride ◽  
Az91d Magnesium Alloy

Effect of Duty Cycle on Microstructure and Corrosion Resistance of MAO Coatings Fabricated on AZ91D Magnesium Alloy in an Optimized Dual Electrolyte

2013 ◽  
Vol 668 ◽  
pp. 779-783 ◽  
Author(s):  
Shu Yan Wang ◽  
Yong Ping Xia ◽  
Li Liu ◽  
Qiao Chen
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Phase Composition ◽  
Magnesium Alloy ◽  
Coating Thickness ◽  
Duty Cycle ◽  
Microarc Oxidation ◽  
Ceramic Coatings ◽  
Relative Content ◽  
Az91d Magnesium Alloy

Ceramic coatings were fabricated on AZ91D magnesium alloy in a novel optimized dual electrolyte by Microarc oxidation. The influence of duty cycle on coating thickness, surface roughness, phase composition, microstructure and corrosion resistance were studied. It is found that both the thickness and surface roughness of coatings increases gradually with the increasing of duty cycle. XRD results show that all the coatings are mainly composed of MgO, Mg2SiO4 and MgAl2O4. The results of potentiodynamic polarization tests indicate that the coating formed at 40% duty cycle exhibits a better corrosion resistance as a result of its relatively compact microstructure and more relative content of Mg2SiO4 and MgAl2O4 phases.

WEAR RESISTANCE OF AZ91D MAGNESIUM ALLOY WITH AND WITHOUT MICROARC OXIDATION COATING AND Ti6Al4V ALLOY IN ARTIFICIAL SALIVA

2009 ◽  
Vol 16 (06) ◽  
pp. 821-830 ◽  
Author(s):  
X. P. ZHANG ◽  
Y. S. ZOU ◽  
F. M. WU ◽  
Z. P. ZHAO ◽  
L. YOU ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Magnesium Alloy ◽  
Wear Mechanisms ◽  
Room Temperature ◽  
Artificial Saliva ◽  
Microarc Oxidation ◽  
Alloy Sample ◽  
Az91d Alloy ◽  
Oxidation Treatment ◽  
Az91d Magnesium Alloy

The wear resistances of AZ91D magnesium alloy with and without microarc oxidation (MAO) coating and Ti 6 Al 4 V alloy in artificial saliva were investigated at room temperature. The wear resistance of AZ91D magnesium alloy in artificial saliva was significantly improved after microarc oxidation treatment. The volume loss of untreated AZ91D magnesium alloy sample was 20.95 times of that of AZ91D magnesium alloy with MAO coating, and that of Ti 6 Al 4 V was 5.42 times of that of MAO. Furthermore, the wear resistance of AZ91D magnesium alloy was lower than that of Ti 6 Al 4 V alloy in artificial saliva. The wear mechanisms of AZ91D magnesium and Ti 6 Al 4 V were discussed. It was found that the wear mechanism of the MAO was associated with abrasion and microfracture. There were two dominative wear mechanisms for AZ91D alloy and Ti 6 Al 4 V alloy under the loading conditions used in the experiment, namely, micro-machining wear and deformation-induced wear.

Effects of Sodium Citrate on MAO Process and Characteristics of Coatings Fabricated on AZ91D Magnesium Alloy

2012 ◽  
Vol 502 ◽  
pp. 320-324 ◽  
Author(s):  
Shu Yan Wang ◽  
Yong Ping Xia ◽  
Li Liu
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sodium Citrate ◽  
Electrochemical Impedance ◽  
Microarc Oxidation ◽  
Dense Layer ◽  
Cross Sectional ◽  
Az91d Magnesium Alloy ◽  
Thickness Meter

Microarc oxidation (MAO) coatings were prepared on AZ91D magnesium alloy in a novel dual electrolyte containing various concentrations of sodium citrate (C6H5Na3O7). The surface and cross-sectional morphologies, coating thickness and surface roughness were characterized by scanning electron microscopy (SEM), layer thickness meter and digital microscope, respectively. The corrosion resistance of coatings was evaluated by electrochemical impedance spectroscopy (EIS). The results showed that both the striking voltage and final voltage decreased gradually with the increase of C6H5Na3O7 concentration. When the C6H5Na3O7 concentration increased, surface roughness increased gradually, while thickness of the coating increased at first and then decreased. The coating formed in the electrolyte containing 5g/L C6H5Na3O7 had a much more uniform and compact microstructure with less micropores and micro-cracks. EIS test showed that the concentration of C6H5Na3O7 mainly affected the corrosion resistance of inner dense layer, and the coating with best corrosion resistance was obtained in the electrolyte containing 5g/L C6H5Na3O7.

scholarly journals Corrosion resistance of the microarc oxidation coatings prepared on magnesium alloy

2018 ◽  
Vol 38 ◽  
pp. 02009
Author(s):  
Ying Lv ◽  
Jun Gang Li ◽  
Ming Zhong Wu ◽  
Zhen Ma ◽  
Jing Qiang Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Microarc Oxidation ◽  
Electrochemical Corrosion ◽  
Ceramic Coatings ◽  
Nacl Solution ◽  
Oxide Coatings ◽  
Az91d Magnesium Alloy ◽  
Oxidation Technology ◽  
Electrochemical Corrosion Resistance

Ceramic coatings were prepared on the surface of AZ91D magnesium alloy by microarc oxidation technology. The effects of different voltages on morphology, phase composition and thickness of the coatings were characterized by SEM and XRD. The corrosion resistance of the coatings was measured by electrochemical workstation. Results indicated that the microarc oxidation coatings prepared in sodium silicate electrolyte exhibited porous surface and mainly comprised MgO, Mg2SiO4 and a small amount of MgAl2O4. The thickness of the oxide coatings increased rapidly with the increase of voltage. The coating prepared at 400V voltage had good electrochemical corrosion resistance in 3.5wt% NaCl solution.

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