Study on Micro-Arc Oxidation Behavior of AZ91 Magnesium Alloy in Aluminate Environmentally Friendly Electrolyte

2020 ◽  
Vol 1003 ◽  
pp. 67-75
Author(s):  
Xian Ming Chen ◽  
Ying Ying Fan
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Magnesium Alloy ◽  
Oxide Film ◽  
Oxidation Behavior ◽  
Salt Spray ◽  
Alkaline Electrolyte ◽  
Az91 Magnesium Alloy ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium

In aluminate alkaline electrolyte the effect of aluminate on the microstructure and properties and the MAO(micro-arc oxidation) behavior of micro-arc oxide film of AZ91 magnesium alloy was studied. Transmission electron microscope(TEM), energy dispersive spectrum (EDS), X-ray diffraction(XRD), salt spray test and scanning electron microscope(SEM)were used to analyze and characterize the structure and properties of the film. The results show that the concentration of aluminate has an important effect on the tank voltage, corrosion resistance, surface morphology and phase structure of micro-arc oxidation film. The corrosion resistance and film quality of the film were increased first and then decreased, but the surface roughness decreased first and then increased with the increase of aluminate concentration from 5g/L to 30g/L. At our work, the concentration of 10g/L aluminate electrolyte is most favorable to the formation of micro-arc oxide film.

scholarly journals Improvement of AZ91 Alloy Corrosion Properties by Duplex NI-P Coating Deposition

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1357 ◽  
Author(s):  
Jaromír Wasserbauer ◽  
Martin Buchtík ◽  
Jakub Tkacz ◽  
Stanislava Fintová ◽  
Jozef Minda ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Az91 Alloy ◽  
Neutral Salt ◽  
Az91 Magnesium Alloy ◽  
Corrosion Properties ◽  
Az91 Magnesium

The corrosion behavior of duplex Ni-P coatings deposited on AZ91 magnesium alloy was studied. The electroless deposition process of duplex Ni-P coating consisted in the preparation of low-phosphorus Ni-P coating (5.7 wt.% of P), which served as a bond coating and high-phosphorus Ni-P coating (11.5 wt.% of P) deposited on it. The duplex Ni-P coatings with the thickness of 25, 50, 75 and 100 µm were deposited on AZ91 magnesium alloy. The electrochemical corrosion behavior of coated AZ91 magnesium alloy was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization method in 0.1 M NaCl. Obtained results showed a significant improvement in the corrosion resistance of coated specimens when compared to uncoated AZ91 magnesium alloy. From the results of the immersion tests in 3.5 wt.% NaCl, 10% solution of HCl and NaOH and 5% neutral salt spray, a noticeable increase in the corrosion resistance with the increasing thickness of the Ni-P coating was observed.

Two-Step Anodization of AZ91 Magnesium Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 653-656 ◽  
Author(s):  
Rong Fa Zhang ◽  
Da Yong Shan ◽  
En Hou Han
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Salt Spray ◽  
Az91 Magnesium Alloy ◽  
Anodic Coating ◽  
Excellent Corrosion Resistance ◽  
Long Time ◽  
Az91 Magnesium ◽  
Short Time ◽  
Salt Spray Testing

Among four AZ91 samples, two were once anodized and the others were twice anodized in two electrolytic baths. After twice anodization, two coatings coexist on the base metal. Surface morphology showed that for one of twice anodic coatings (sample 2), the second coating only existed on some places and sealed some pores of the first coating after short time on the second anodizing. However, for another twice anodic coating (namely sample 4), the second anodization spent very long time and the coating was thick and loose. Salt spray testing showed that sample 2 had the most excellent corrosion resistance and the reason is discussed.

Effects of Erbium Addition on the Corrosion Resistance and Microstructure of AZ91 Magnesium Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1221-1224 ◽  
Author(s):  
Zhong Jun Wang ◽  
Yang Xu ◽  
Jing Zhu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Discontinuous Precipitation ◽  
Az91 Magnesium Alloy ◽  
Continuous Precipitation ◽  
Az91 Magnesium ◽  
Precipitation Phase

The microstructures and corrosion resistance of AZ91 and AZ91+0.5 wt.% erbium (Er) magnesium alloys were studied, respectively. The results show that the Er addition in scrap AZ91 magnesium alloy can improve the corrosion resistance, markedly. The discontinuous precipitation phase (DPP) for Mg17Al12was retarded and the amount of DPP was decreased by 41% due to the formation of Al8ErMn4phase during solidification. The amount of continuous precipitation phase (CPP) in grains was decreased by 8% because of the formation of Al7ErMn5phase during solidification.

Corrosion and Protection of Magnesium Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1078-1082 ◽  
Author(s):  
Yang Yang Lv ◽  
Ling Feng Zhang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Automotive Industry ◽  
Physical And Mechanical Properties ◽  
Current Status ◽  
Strain Rates ◽  
Metallic Materials ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Magnesium alloy as a green material in the 21st century, because of its excellent physical and mechanical properties of metallic materials as an ideal in the automotive industry, electronic industry and aviation, aerospace and other industries[1]. However, poor corrosion resistance of magnesium alloys become an important issue hinder application of magnesium alloys[2]. So magnesium alloy corrosion problems and the current status of research paper reviews several magnesium alloy protection methods at home and abroad, and also highlighted with our latest laser shock (LSP) study of AZ91 magnesium alloy at high strain rates of corrosion resistance results.

The Research of Micro Arc Oxidation Behavior of the Magnesium Alloy

2013 ◽  
Vol 803 ◽  
pp. 191-195
Author(s):  
Yun Long Zhang ◽  
Mu Qin Li ◽  
Yu Min Zhang ◽  
Ming Hu
Keyword(s):  
Corrosion Resistance ◽  
Phase Composition ◽  
Magnesium Alloy ◽  
Surface Morphology ◽  
Electrolyte Solution ◽  
Oxidation Behavior ◽  
Corrosion Current ◽  
Positive Potential ◽  
Micro Arc Oxidation ◽  
Oxidation Technology

The ceramics coating hadobtained by the micro arc oxidation technology in order to resolve thecorrosion resistance of the Mg alloy.The phase composition, surface morphology,gained weight and polarization behavior of the micro arc oxidation coating wasinvestigated in details. After the introduce of the sodiumcitrate in the electrolyte solution, thespecimen had high relatively positive potential and low corrosion current, sodoped sodium citratewould improve the corrosion resistance properties of the Mg alloy .

Ceria Coatings Prepared by Sol-Gel Approach on AZ91 Magnesium Alloy

2017 ◽  
Vol 898 ◽  
pp. 1369-1380 ◽  
Author(s):  
Hui Min Han ◽  
Dan Tong Wang ◽  
Hua Qian Yu ◽  
Min Zuo ◽  
Li Hong Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sol Gel ◽  
Electrochemical Corrosion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

The ceria coatings on AZ91 substrates were successfully synthesized by chemical conversion and the corrosion resistance of AZ91 samples with and without ceria coatings were evaluated by means of electrochemical corrosion in 3.5 wt.% NaCl solution. According to the parameters derived from the polarization date, the Icorr (the corrosion current density) values of the coated samples are smaller than that of bare one, indicating that the corrosion resistance of AZ91 alloys has been improved to some extent. The influence of fluoridated pretreatment, inter-layer heat treatment, sintering temperature and the layer of films on the performance of ceria coatings were also investigated. It was found that the inter-layer heat treatment has no influence on improving the anticorrosion resistance of AZ91 alloy. In comparison with the bare one, the Icorr of optimal sample is about 0.0219mA/cm2, which decreases by two orders of magnitude, indicating that the ceria coatings could significantly improve the corrosion resistance of AZ91 magnesium alloy.

Research on Heavy-Duty Coating Protection System of Magnesium Alloy

2015 ◽  
Vol 1119 ◽  
pp. 525-528
Author(s):  
Ru Tang Yan ◽  
Yuan Yuan Li ◽  
Chun Wei She ◽  
Hua Geng Li ◽  
Hua Pan Li
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Salt Spray ◽  
Salt Spray Test ◽  
Protection System ◽  
Test Time ◽  
Test Results ◽  
Ageing Test ◽  
Micro Arc Oxidation ◽  
Resistance Performance

The poor corrosion resistance of magnesium alloys become the bottleneck restricting its development. Based on micro-arc oxidation (MAO) technology and the characteristics of fluorocarbon coating the surface of magnesium alloy build a high corrosion protection system, namely: Based on micro-arc oxidation coating fluorocarbon coatings. The formation of the composite coating through the resistance to ageing test through the resistance to ageing test, acid and alkali experiment and salt spray test results show the excellent corrosion resistance performance. Among them, the resistance to salt spray test time can reach 1500 h, which breaks the bottleneck of magnesium alloy corrosion resistance of 1000 h.

Corrosion Resistance of RE-AZ91 Magnesium Alloys

2014 ◽  
Vol 933 ◽  
pp. 66-70
Author(s):  
Jun Jie Yang ◽  
Yao Li ◽  
Ping Xue
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Mg Alloy ◽  
Constant Voltage ◽  
High Tensile Strength ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Good Heat Resistance ◽  
Good Heat

Rare Earth (RE) were added to industrial AZ91 magnesium alloy, so that RE-AZ91 Mg alloy was produced by the process of die casting, so as to study the effect of RE on corrosion resistance and tensile strength of Mg alloy. The experiment results show that RE addition could improve the tensile strength and corrosion resistance of magnesium alloy at a certain amount of RE. RE-AZ91 had a good heat resistance, corrosion resistance at a high temperature or in the environment applied constant voltage, with a high tensile strength.

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