Microstructure and Corrosion Resistance of Microarc Oxidation Coatings on AZ31 Magnesium Alloy Extrusion Profiles

2012 ◽  
Vol 557-559 ◽  
pp. 1993-1997
Author(s):  
Jie Ma ◽  
Yuan Sheng Yang ◽  
Xiu Chun Wang ◽  
Jing Zhang ◽  
Shuo Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Microarc Oxidation ◽  
Corrosion Current ◽  
Spot Test ◽  
Pulse Voltage ◽  
Az31 Magnesium Alloy ◽  
Oxidation Treatment ◽  
Coating Surface ◽  
Structure Surface

Microarc oxidation coatings were prepared on the surface of AZ31 magnesium alloy profiles. Oxidation time of the coatings was between 5min-10min. The phase structure, surface morphology and corrosion resistance of the coatings were investigated using SEM, XRD, copper sulfate spot test and polarization curve test. The results indicate: the main phase compositions of the microarc oxidation coatings are MgO, Mg2SiO4 and MgSiO3; with increasing pulse voltage, the micropore diameter of the coating surface becomes larger, the micropore number reduces and the coating surface roughness increases; the corrosion current density of magnesium alloy reduces significantly after microarc oxidation treatment. The pulse voltage of microarc oxidation should be controlled between 240V-360V to obtain the best corrosion resistance.

Effect of Impulse Voltage on Microstructure and Corrosion Resistance of Microarc Oxidation Coatings on AZ80 Magnesium Alloy

2013 ◽  
Vol 575-576 ◽  
pp. 418-422 ◽  
Author(s):  
Jie Ma ◽  
Yuan Sheng Yang ◽  
Xiu Chun Wang ◽  
Jing Zhang ◽  
Shuo Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Current Density ◽  
Microarc Oxidation ◽  
Corrosion Current ◽  
Spot Test ◽  
Pulse Voltage ◽  
Oxidation Treatment ◽  
Az80 Magnesium Alloy ◽  
Structure Surface

Microarc oxidation coating and microarc oxidation-fluorocarbon coating were prepared on the surface of AZ80 magnesium alloy profiles. The phase structure, surface morphology and corrosion resistance of the coatings were investigated using SEM, XRD, copper sulfate spot test and polarization curve test. The main phase compositions of the microarc oxidation coatings were MgO, Mg2SiO4, MgSiO3, MgF2 and MgAl2O4. With increasing pulse voltage, the oxidation coating became thicker and the microstructure of the coating surface became compact; therefore the coating corrosion resistance was improved. The oxidation coating with pulse voltage of microarc oxidation controlled between 300-438V obtained the best corrosion resistance. The corrosion current density of magnesium alloy reduced 1-3 orders of magnitude after microarc oxidation treatment with increasing pulse voltage, and the corrosion resistance of microarc oxidation-fluorocarbon coating is desirable.

Corrosion Behavior of AZ31 Magnesium Alloy with Microarc Oxidation Film Irradiated by High-Intensity Pulsed Ion Beam

2008 ◽  
Vol 373-374 ◽  
pp. 460-463 ◽  
Author(s):  
X.G. Han ◽  
P. Li ◽  
X.P. Zhu ◽  
M.K. Lei
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
High Intensity ◽  
Electrochemical Impedance ◽  
Ion Beam ◽  
Microarc Oxidation ◽  
Az31 Magnesium Alloy ◽  
Noticeable Improvement ◽  
Original Films ◽  
Sealing Layer

The microarc oxidation (MAO) films on AZ31 magnesium alloy were modified by high-intensity pulsed ion beam (HIPIB) at an ion current density of 200 A/cm2 with 1-5 shots. The modified MAO films presented a corrosion resistance superior to that of the original films. Scanning electron microscopy (SEM) observation revealed that a sealing layer was formed on the MAO films by HIPIB irradiation. The corrosion behaviors of the MAO films in 3.5 % NaCl solution were characterized by using electrochemical impedance spectroscopy (EIS). The noticeable improvement in the corrosion resistance of MAO films is attributed to the blocking effect of the sealing layer that hinders the process of electrolyte penetrating the MAO films to the magnesium alloy.

Effect of Negative Pulse Voltage on the Microstructure and Corrosion Resistance of Microarc Oxidation Film of A356 Aluminum Alloy

2011 ◽  
Vol 675-677 ◽  
pp. 1193-1196 ◽  
Author(s):  
Guang Huai Peng ◽  
Bao Jun Han ◽  
Ling Fang ◽  
Xue Feng Guo ◽  
Xiao Lian Zhang
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Microarc Oxidation ◽  
Film Surface ◽  
Corrosion Current ◽  
Pulse Voltage ◽  
Thickness Gauge ◽  
A356 Aluminum Alloy ◽  
Negative Pulse ◽  
A356 Aluminum

The effect of negative pulse voltage on the microstructure and corrosion resistance of microarc oxidation film of A356 aluminum alloy treated by microarc technique was investigated by SEM, coating thickness gauge and electrochemical workstation etc. The results show the negative pulse voltage greatly influences the microstructure and corrosion resistance of microarc oxidation film by its electrode reaction. The film thickness increases while the size of pore and roughness of the film surface decreases initially and then increases with negative pulse voltage increasing. The microarc oxidation treatment considerably improved corrosion resistance, and the highest corrosion potential was -1.16V, which was 0.38V higher than that of substrate, and the corrosion current was lower than that of substrate about three orders of magnitude.

Influence of Current Density on Structure and Performance of Micro-Arc Oxidation Coatings on AZ31 Magnesium Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 562-566 ◽  
Author(s):  
Mei Yang ◽  
Zheng Lei ◽  
Xiao Hong Wang ◽  
Ping Wang ◽  
Jun Yang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Current Density ◽  
Adhesion Force ◽  
Water Solution ◽  
Corrosion Current ◽  
Az31 Magnesium Alloy ◽  
Positive Direction ◽  
Micro Arc Oxidation ◽  
And Performance

In the Na2SiO3-NaOH-C3H8O3electrolyte system,the micro-arc oxidation (MAO) coatings were prepared on AZ31 magnesium alloy when J=2A/dm2,4A/dm2,8A/dm2and 12A/dm2.The relations of current density with microstructure and performance of the MAO coatings on AZ31 were studied by means of SEM, XRD, HVS-1000 micro Vicker, MFT-4000 Scratch Tester and electro-chemical method. The results show that when current density increases,the thickness,growth rate,micro-hardness and the contents of MgO and Mg2SiO4of MAO coatings increase,but the adhesion force between MAO coating and substrate decreases, the millipores and the roughness become larger.The corrosion resistance of MAO coatings increases firstly and then decreases with the increasing current density.The corrosion resistance of MAO coating,which J=6 A/dm2,is the best in 4.5% NaCl water solution,whose corrosion current density reduces by 3 orders of magnitude, and corrosion potential increases 1078mV in positive direction.

Al–AlN composite coatings on AZ31 magnesium alloy for surface hardening and corrosion resistance

Vacuum ◽  
2021 ◽  
pp. 110146
Author(s):  
Wenling Xie ◽  
Yiman Zhao ◽  
Bin Liao ◽  
Pan Pang ◽  
Dongsing Wuu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Surface Hardening ◽  
Composite Coatings ◽  
Az31 Magnesium Alloy

Phosphate film free of chromate, fluoride and nitrite on AZ31 magnesium alloy and its corrosion resistance

2012 ◽  
Vol 22 (11) ◽  
pp. 2713-2718 ◽  
Author(s):  
Xue-jun CUI ◽  
Chun-hai LIU ◽  
Rui-song YANG ◽  
Ming-tian LI ◽  
Xiu-zhou LIN ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Az31 Magnesium Alloy ◽  
Phosphate Film
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