Enhancing Conductivity and Corrosion Resistance by Organic Coatings on AZ31 Magnesium Alloy Treated by Micro-Arc Oxidation

2019 ◽  
Author(s):  
Xiuping Zhang ◽  
Lei Li ◽  
Yaozhao Mu ◽  
Yanxiang Xie ◽  
Jun Dai ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Carbon Black ◽  
Composite Coatings ◽  
Electrochemical Corrosion ◽  
Organic Coating ◽  
Organic Coatings ◽  
Micro Arc Oxidation ◽  
Conductive Particles

Abstract In this study, an organic coating, in combination of a micro-arc oxidation ceramic layer, was prepared on the surface of a magnesium alloy (AZ31) to achieve both functions of corrosion resistance and electrical conductivity. By using carbon black as conductive particles and epoxy resin as matrix, organic coatings of various weight fractions were applied on the AZ31 surface treated by micro-arc oxidation through adjusting the contents of the conductive particles and non-conductive matrix. Electrical conductivity and corrosion resistance of organic coatings were measured. The results show that the organic coatings can improve the electrical conductivity of the AZ31 material treated by micro-arc oxidation, and the conductivity changes with the ratio between the carbon black particles and non-conductive matrix. The smallest resistance value of the organic coatings reached 130Ω. Also, the organic coating can further improve the corrosion resistance of the AZ31 material. The electrochemical corrosion tests show that the corrosion potential of the AZ31 material with composite coatings was at least 0.6V higher than that of AZ31 only with micro-arc oxidation treatment.

The Effect of n-TiO2 on Corrosion and Biological Activity of Biocoatings Coated by Ultrasound Micro-Arc Oxidation on Pure Magnesium

2014 ◽  
Vol 633 ◽  
pp. 418-421 ◽  
Author(s):  
Chen Ma ◽  
Yan Gao ◽  
Li Jie Qu ◽  
Mu Qin Li ◽  
Jin Long Yue ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Biological Activity ◽  
Magnesium Alloy ◽  
Simulated Body Fluid ◽  
Surface Morphology ◽  
Body Fluid ◽  
Electrochemical Corrosion ◽  
Order Of Magnitude ◽  
Micro Arc Oxidation ◽  
Different Content

In order to improve the corrosion resistance and bioactivity of magnesium alloy coated by ultrasound micro-arc oxidation (UMAO), different content of n-TiO2 was added into silicate electrolyte. Electrochemical corrosion and simulated body fluid (SBF) soaking were conducted, and the surface morphology, phase structure and composition also were analyzed. The results indicated that Ecorr and Icorr of UMAO biocoatings with n-TiO2 increased and decreased an order of magnitude with increase of n-TiO2, respectively. The corrosion resistance of coatings with adding 4.8g/L n-TiO2 into electrolyte was the best. After soaking in SBF, the samples increased loose weight firstly and then increased weight to form Mg3Ca (CO3)4, Mg10Cl (OH)18·5H2O and Na4Mg2(PO4) ·2H2O new phases and Mg, MgO, MgSiO3 were still exit, which showed that good bioactivity of the UMAO coatings with n-TiO2.

Corrosion Behavior of the Composite Coatings Prepared on Magnesium Alloy AZ91 in Na2SO4 Solution

2014 ◽  
Vol 900 ◽  
pp. 522-525
Author(s):  
Wei Shang ◽  
Zhou Lan Yin ◽  
Yu Qing Wen ◽  
Xu Feng Wang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Sol Gel ◽  
Alloy Az91 ◽  
Magnesium Alloy Az91 ◽  
Micro Arc Oxidation ◽  
Gel Technique

The composite coatings were obtained on a magnesium alloy by micro-arc oxidation (MAO) and sol-gel technique. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behavior of MAO coating and composite coatings in a 3.5% Na2SO4 solution. The results show that corrosion behavior of the MAO coating and composite coatings are different at different immersion times. The corrosion resistance of composite coatings is good than that of MAO coating.

A Preliminary Study of Anodization and Electroless Ni–P Plating on AZ80 Magnesium Alloy

2011 ◽  
Vol 299-300 ◽  
pp. 663-666 ◽  
Author(s):  
Ping Shi ◽  
Xue Dong Han
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Surface Modifications ◽  
Atomic Ratio ◽  
Az80 Magnesium Alloy ◽  
Micro Arc Oxidation ◽  
Preliminary Study ◽  
Electroless Ni

Magnesium alloys are being used as structural components in industry because of their high strength to weight ratio. But their high electrochemical activity and poor corrosion resistance limited their applications. Therefore, surface modifications are needed for protection purpose. This paper studied the anodic micro-arc oxidation and electroless Ni-P plating surface modifications on AZ80 magnesium alloy. The SEM, XRD and EDS were used to characterize the surface coating. It shows that a micro-porous MgO layer with the pores size 5 – 20 μm was fabricated on the bare magnesium alloy. The nodule Ni-P deposition could be prepared on the out layer of MgO with Ni/P atomic ratio being 1.4. The pores in MgO layer could be sealed by the following Ni-P deposition. Therefore the corrosion resistance of the magnesium alloy could be further improved.

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

scholarly journals Preparation and Characterization of a Sol–Gel AHEC Pore-Sealing Film Prepared on Micro Arc Oxidized AZ31 Magnesium Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 784
Author(s):  
Longlong Zhang ◽  
Yuanzhi Wu ◽  
Tian Zeng ◽  
Yu Wei ◽  
Guorui Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sol Gel ◽  
Oxide Coating ◽  
Az31 Magnesium Alloy ◽  
Hydroxyethyl Cellulose ◽  
Gel Spinning ◽  
Test Analysis ◽  
Pore Sealing ◽  
Micro Arc Oxidation

The purpose of this study was to improve the cellular compatibility and corrosion resistance of AZ31 magnesium alloy and to prepare a biodegradable medical material. An aminated hydroxyethyl cellulose (AHEC) coating was successfully prepared on the surface of a micro-arc oxide +AZ31 magnesium alloy by sol–gel spinning. The pores of the micro-arc oxide coating were sealed. A polarization potential test analysis showed that compared to the single micro-arc oxidation coating, the coating after sealing with AHEC significantly improved the corrosion resistance of the AZ31 magnesium alloy and reduced its degradation rate in simulated body fluid (SBF). The CCK-8 method and cell morphology experiments showed that the AHEC + MAO coating prepared on the AZ31 magnesium alloy had good cytocompatibility and bioactivity.

Research on Corrosion Resistance of AZ91D Magnesium Alloy Coated with Epoxy Resin

2011 ◽  
Vol 686 ◽  
pp. 292-299
Author(s):  
Yong Gang Li ◽  
Ying Hui Wei ◽  
Li Feng Hou ◽  
Yun Tian ◽  
Li Jing Yang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Adhesion Force ◽  
Die Casting ◽  
Corrosion Current ◽  
Scratch Test ◽  
Organic Coating ◽  
Thin Wall ◽  
Scanning Method ◽  
Az91d Magnesium Alloy

The corrosion resistance of a 1~2mm thick AZ91D magnesium alloy die-casting coated with epoxy varnish after phosphatizing was tested. Zinc phosphating solution was used. In the experiment, uniform paint was obtained by dipping method. Scratch test showed that the adhesion force between the coating and matrix is excellent. Within the test range the optimal phosphating temperature and time are 50°C and 1 min tested by dynamic potential scanning method. With the organic coating the corrosion current density decreased 3 orders of magnitude, the polarization resistance increased 3 orders of magnitude. The coated specimens were immersed in10% H2SO4, 10% NaOH and acetone for 10 days, respectively. The results showed that blistering did not occur on the paint films. This work illustrated that the simple zinc phosphating process combined with simple organic coating can meet the corrosion resistance requirements of thin-wall die casting magnesium components that require higher quality appearance.

scholarly journals Fabrication, Wear, and Corrosion Resistance of HVOF Sprayed WC-12Co on ZE41 Magnesium Alloy

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 502 ◽  
Author(s):  
Sonia García-Rodríguez ◽  
Antonio Julio López ◽  
Victoria Bonache ◽  
Belén Torres ◽  
Joaquín Rams
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Thermal Spraying ◽  
Electrochemical Corrosion ◽  
High Energy ◽  
Wear And Corrosion ◽  
Wear And Corrosion Resistance ◽  
Oxygen Fuel ◽  
Mass Increase ◽  
Temperature Melting

This study shows that WC-12Co coatings with low porosity and high wear and corrosion resistance can be applied by high velocity oxygen-fuel (HVOF) on a low melting and highly flammable ZE41 magnesium alloy. This provides a novel and promising use of the high-energy thermal spraying technique on low temperature melting substrates. The spraying distance used was 300 mm, which is between two and three times the recommended distanced for HVOF coating with WC-12Co on steels. Despite this, the WC-12Co coatings obtained were homogeneous, crack-free, and dense. The coatings were very well adhered to the substrates and the spraying distance allowed avoiding any thermal affectation of the substrate. The thickness of the coatings was limited to 45 μm to avoid a big mass increase in the samples. The effect of the number of layers, the O2/H2 ratio and the gas transport flow in the coating was studied. The coatings reduced the wear rate of the substrate by 104 times, making them wear resistant. Electrochemical corrosion tests were conducted to study the corrosion protection of the coatings, showing that it is possible to protect the magnesium substrate for 96 h in contact with 3.5 wt.% NaCl aqueous solution.

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