The Study of Electrochemical Property of Organic Coating on Magnesium Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 433-436
Author(s):  
Bai Yang Lou ◽  
Yao Tang ◽  
Ke Zai Miao ◽  
Bin Xu
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Base Alloy ◽  
High Strength ◽  
Corrosion Current ◽  
Organic Coating ◽  
Open Circuit ◽  
Corrosion Property ◽  
Organic Coatings ◽  
Specific Strength

Magnesium Alloys are of low density, high specific strength and high strength, leading to much application prospect in industry and civilian use. However, the alloys are restrictedly used because of easy corrosion. In this paper, The Organic coatings on Magnesium Alloys are made. The electrochemical properties of organic coatings are researched by scanning electron microscope (SEM), stereoscopic microscope and electric-chemistry Work station. The research results show that the curves of open-circuit current to time and Tafel polarization shuffle more for the Pu and ER/PU coatings than for base alloy. With addition of the coating, the magnesium alloy has much low corrosion current density (icorr) and high polarization resistance (Rp), and then its Anti-corrosion Property is evidently improved.

scholarly journals Mechanical Properties and Microstructure of the Magnesium Alloy Mg-6.8Y-2.5Zn-0.5Al Produced by Casting and Hot Rolling

2018 ◽  
Vol 918 ◽  
pp. 3-12 ◽  
Author(s):  
Kristina Neh ◽  
Madlen Ullmann ◽  
Rudolf Kawalla
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Hot Rolling ◽  
High Strength ◽  
Final Thickness ◽  
Good Thermal Stability ◽  
Specific Strength ◽  
Automotive Electronic ◽  
Rolling Temperatures

In recent years, magnesium alloys have been received much attention as important structural materials for lightweight components in automotive, electronic and space industries because of the low density, high specific strength, high damping capacities and good casting properties. Among various magnesium alloys, rare earth (RE) containing alloys are known to show high strength, excellent creep resistance, and good thermal stability. Long period stacking ordered structures (LPSO) being responsible for the improved property profile in some Mg–RE alloys. One promising system are the Mg-Y-Zn alloys, which are predominantly processed via extrusion. Only a few studies are focused on hot rolling. However, these works are confined to rolling temperatures between 350 °C and 420 °C. The present paper summarizes the development of a rolling technique including pass schedule and heat treatment for the magnesium alloy Mg-6.8Y-2.5Zn-0.5Al in as-cast condition in order to produce sheets with a final thickness of 2.5 mm. The investigations are accompanied by the characterization of the microstructure as well as the determination of the mechanical properties.

scholarly journals Effect of (NH4)2ZrF6, Voltage and Treating Time on Corrosion Resistance of Micro-Arc Oxidation Coatings Applied on ZK61M Magnesium Alloys

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7410
Author(s):  
Jiahui Yong ◽  
Hongzhan Li ◽  
Zhengxian Li ◽  
Yongnan Chen ◽  
Yifei Wang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Property ◽  
Xps Analysis ◽  
Orthogonal Experiments ◽  
Micro Arc Oxidation

The effects of (NH4)2ZrF6 concentration, voltage and treating time on the corrosion resistance of ZK61M magnesium alloy micro-arc oxidation coatings were studied by orthogonal experiments. The SEM result shows that the surface roughness and porosity of MAO coatings increased with (NH4)2ZrF6 concentration, voltage and treating time as a whole, except the porosity decreased with treating time. EDS, XRD and XPS analysis show that (NH4)2ZrF6 was successfully incorporated into coatings by reactive incorporation, coatings are dominantly composed of ZrO2, MgO, MgF2 and amorphous phase Mg phosphate. Potentiodynamic polarization was used to evaluate the corrosion property of coatings. When the concentration of (NH4)2ZrF6 is 6 g/L, the voltage is 450 V, and the treating time is 15 min, the coating exhibits the best corrosion resistance which corrosion current density is four magnitudes lower than substrate attributed to the incorporation of ZrO2 and the deposition of MgF2 in the micropores.

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.

Formability of AZ31 Magnesium Alloy Sheet in Dry Press Forming Using Diamond-Coated Dies

2009 ◽  
Author(s):  
S. Tsuda ◽  
S. Yoshihara ◽  
S. Kataoka
Keyword(s):  
Surface Roughness ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Deep Drawing ◽  
Chemical Vapor ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Specific Strength ◽  
Press Forming ◽  
Forming Tools

Dry press forming which hasn’t used lubricants in the process is the attractive forming technique of zero emission for the lubricants. As one of the dry press forming techniques, the usage of dies coated with a chemical vapor deposition (CVD) diamond film, which are expected to be applied to forming tools owing to their high tribological properties, abrasion resistance and heat resistance, has been proposed. Magnesium alloys have attracted attention owing to their advantages over what such as, high specific strength and ease of recycling. However, they have intractable characteristics, and it is necessary to perform the forming technique at high temperature and to consider lubrication condition. In this study, diamond-coated dies were used in the deformation of magnesium alloy sheets without lubricants in press forming, and the formability of magnesium alloy and its effect on the surface texture of a formed-cup were investigated. Dry deep-drawing tests and dry ironing tests were carried out to estimate the effect of the diamond-coated dies on the formability of magnesium alloy sheets. Furthermore, the formability obtained using the above-mentioned tests was compared with that obtained in tests using non-lubricant dies with traditional lubricant. AZ31 magnesium alloy sheets (thickness: t0 = 0.5 mm) were deformed at 200 °C in dry deep-drawing tests. From the results, it was found that what can be deformed using diamond-coated dies. Moreover, a 20% reduction in drawing force was confirmed compared with the usage of the traditional lubricant (MoS2). Meanwhile, dry ironing tests were performed under conditions of 10% ironing ratio by a method similar to the dry deep-drawing tests. In general, the ironing process, which is the most difficult step in lubrication in sheet forming, has been enabled by the diamond coating technique. Furthermore, it was observed that the surface roughness of the formed-cup walls using the diamond-coated dies was 0.4 μmRz, and, 1.3 μmRz in case of MoS2. It was confirmed that the application of diamond-coated dies improved the surface roughness of the formed-cup. It produced an improvement in the formability of magnesium alloys compared with the traditional lubrication technique (use of MoS2). It was concluded that the validity of the use of diamond-coated dies became clear.

Corrosion resistance and characterization studies of calcium series chemical conversion film via green pretreatment on magnesium alloy

2016 ◽  
Vol 63 (6) ◽  
pp. 508-512
Author(s):  
Fengjing Wu ◽  
Xiaojuan Liu ◽  
Xin Xiao
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Organic Coating ◽  
Hazardous Substances ◽  
Surface Pretreatment ◽  
Content Type ◽  
Az80 Magnesium Alloy

Purpose Magnesium alloys, although valuable, are reactive and require protection before its application in many fields. The purpose of this study was to evaluate a novel anticorrosive chemical conversion film on AZ80 magnesium alloy by environmental-friendly calcium series surface pretreatment. Design/methodology/approach The corrosion resistance of the film was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 Wt.% NaCl solution. The surface morphologies, microstructure and composition of the film were investigated by scanning electron microscopy and energy-dispersive spectroscopy. Findings The corrosion current density of the calcium series film decreased by more than one order of magnitude as compared to that of the AZ80 magnesium alloy. The conversion film presented dry-mud morphology, and its thickness was estimated to be approximately 4 μm. The conversion film was highly hydrophilic, and the organic coating adhesion on treated AZ80 surface was approximately 13.5 MPa. Originality/value Excellent performance of the calcium-based chemical conversion film on Mg alloy was obtained, which does not contain heavy metals or fluorides and completely conforms to European RoHS (Restriction of Hazardous Substances) standard.

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.

Electrophoretic Composite Coatings on Magnesium Alloys

2015 ◽  
Vol 245 ◽  
pp. 97-102
Author(s):  
Dmitry V. Mashtalyar ◽  
Sergey V. Gnedenkov ◽  
Sergey L. Sinebryukhov ◽  
Igor M. Imshinetsky
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Electrophoretic Deposition ◽  
Plasma Electrolytic Oxidation ◽  
Corrosion Current Density ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

Investigation results of the composite coatings obtained on MA8 magnesium alloy by plasma electrolytic oxidation (PEO) and post-treated by electrophoretic deposition of superdispersed polytetrafluoroethylene (SPTFE) are presented. Comprehensive research of electrochemical and mechanical properties of the obtained polymer-containing coatings on the magnesium alloy has been performed. It has been established that composite coatings to decrease the corrosion current density by three orders of magnitude (down to Ic = 2.0×10-10 A/cm2) and the wear by two orders of magnitude (down to 1.2×10-6 mm3/(N·m)), as compared to the basic PEO-coating.

Comparison of Electrochemical and Chemical Corrosion Behavior of MRI 230D Magnesium Alloy with and without Plasma Electrolytic Oxidation Treatment

2015 ◽  
Vol 364 ◽  
pp. 27-34
Author(s):  
Barbara Kazanski ◽  
Alex Lugovskoy ◽  
Ohad Gaon ◽  
Michael Zinigrad
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Behavior ◽  
Plasma Electrolytic Oxidation ◽  
Electrochemical Impedance ◽  
Weight Ratio ◽  
Open Circuit ◽  
Chemical Corrosion ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

Magnesium is one of the lightest metals and magnesium alloys have quite special properties, interest to which is continuously growing. In particular, their high strength-to-weight ratio makes magnesium alloys attractive for various applications, such as transportation, aerospace industryetc. However, magnesium alloys are still not as popular as aluminum alloys, and a major issue is their corrosion behavior.The present research investigated the influence of the PEO treatment on the corrosion behavior of MRI 230M magnesium alloy. Plasma electrolytic oxidation (PEO) of an MRI 230M alloy was accomplished in a silicate-base electrolyte with KF addition using an AC power source.The corrosion behavior of both treated and untreated samples was evaluated by open circuit potential (OCP) measurements, electrochemical impedance spectroscopy (EIS), linear polarization tests, linear sweep voltammetry (Tafel extrapolation) and chemical methods, such as mass loss and hydrogen evolution, in neutral 3.0 wt% NaCl solution.According to the tests results, PEO process can affect the corrosion resistance of MRI 230M magnesium alloy, though its action is not always unambiguous. An attempt to explain the influence of the PEO treatment on the corrosion behavior of the alloy is presented.

Effect of Rolling Speed on Deformability and Microstructure in Rolling of AZ31B Magnesium Alloy

2010 ◽  
Vol 89-91 ◽  
pp. 227-231 ◽  
Author(s):  
Go Hamada ◽  
Tetsuo Sakai ◽  
Hiroshi Utsunomiya
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
High Speed ◽  
Rolling Speed ◽  
Single Pass ◽  
Specific Strength ◽  
Superior Mechanical Properties ◽  
Hcp Structure ◽  
Edge Cracking

Magnesium alloys are expected to be used widely as structural materials because of their lowest density (1.8g/cm3) among all practical alloys and superior specific strength. However, magnesium alloys exhibit poor ductility due to its hcp structure and inactiveness of non-basal slip systems below 523K. Accordingly, magnesium alloy sheets had to be rolled at elevated temperature to avoid edge cracking and fracture during rolling. The present authors succeeded in single pass large draught rolling of AZ31 magnesium alloy sheets below 473K without heating rolls by rolling at the speed higher than 1000m/min. The rolled and quenched sheets had fine recrystallized microstructure and exhibited excellent mechanical properties. It was found that the high speed rolling is a promising method not only for increasing productivity but also for controlling microstructures and improving mechanical properties. If the above mentioned advantages of high speed rolling can be drawn from the rolling at the speed lower than 1000m/min, it is possible to mass-produce magnesium alloy sheets having superior mechanical properties at lower cost. In this study, we tried to determine the lower limiting rolling speed at which we can obtain advantages of high speed rolling. We revealed that the thickness could be reduced about 60% by single pass operation even at 250m/min without heating rolls. The rolled and quenched sheets had equiaxed fine recrystallized microstructure. For example, the mean grain size of 2.1m was obtained in the AZ31B sheet rolled at 250m/min at room temperature to the reduction of 60%.

Mechanical Properties of Al2O3 Reinforced Cast and Hot Extruded Al Based Metal Matrix Composites

2015 ◽  
Vol 813-814 ◽  
pp. 208-212
Author(s):  
S. Ghanaraja ◽  
K.L. Vinuth Kumar ◽  
K.S. Ravikumar ◽  
B.M. Madhusudan
Keyword(s):  
Mechanical Properties ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Base Alloy ◽  
High Strength ◽  
Matrix Composites ◽  
Specific Strength ◽  
Good Corrosion Resistance ◽  
High Specific Strength ◽  
Low Weight

The Synthesis of aluminium matrix composites is receiving considerable emphasis in meeting the requirements of various industries. Due to the desired properties such as low weight, high specific strength, good corrosion resistance and excellent wear resistance, they have received a great interest in the recent years. Metal-matrix composites (MMCs) based on aluminium and magnesium has emerged as an important class of materials and Al2O3can be considered as ideal reinforcements, due to their high strength, high aspect ratio and thermo-mechanical properties. The objective of this work is to reinforce Al 1100-Mg alloy with different wt% of Al2O3(0, 3, 6, 9 and 12) was added by melt stirring method and Extrusion is carried out (extrusion ratio of 12.25) for the same alloy and composites. Mechanical property like hardness and tensile properties have been investigated for cast and extruded of base alloy and composites.

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