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.

scholarly journals Effect of V2O5 Additive on Micro-Arc Oxidation Coatings Fabricated on Magnesium Alloys with Different Loading Voltages

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1146
Author(s):  
Zhanying Wang ◽  
Ying Ma ◽  
Yushun Wang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
High Voltage ◽  
Spinel Structure ◽  
Corrosion Current Density ◽  
Low Voltage ◽  
Corrosion Current ◽  
Corrosion Property ◽  
Micro Arc Oxidation ◽  
New Phase

Effect of V2O5 additive in silicate-containing electrolyte on AZ91D magnesium alloys treated by micro-arc oxidation (MAO) technology under different loading voltages was investigated. The results showed that vanadium was well up-taken into the coating chemically. Moreover, a new phase of MgV2O4 with spinel structure was obtained in MAO coatings due to V2O5 added into the electrolyte. The MgV2O4 phase was responsible for the coatings exhibiting brown color and also was beneficial to improving the anti-corrosion property. In spotting tests, the corrosion resistances of coatings prepared under the high voltage are about 6–9 times higher than those of the low voltage because of the thicker coatings of the former. In potentiodynamic polarization tests, the coatings’ corrosion resistances were improved with the addition of V2O5, which was more significant under the low voltage than that under the high voltage. When the concentration of V2O5 was 0.2 g/L, the corrosion current density of the coating was the lowest, which means that the coating’s corrosion resistance under the low voltage is the best. Hence, it is necessary to carry out targeted design of the coating’s microstructure according to the different applications.

scholarly journals Preparation of medical Mg–Zn alloys and the effect of different zinc contents on the alloy

2022 ◽  
Vol 33 (1) ◽  
Author(s):  
Yunpeng Hu ◽  
Xuan Guo ◽  
Yang Qiao ◽  
Xiangyu Wang ◽  
Qichao Lin
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Current Density ◽  
Bending Strength ◽  
Corrosion Current ◽  
Human Bone ◽  
Maximum Compressive Stress ◽  
Good Biocompatibility

AbstractIn recent years, along with the development and application of magnesium alloys, magnesium alloys have been widely used in automotive, aerospace, medicine, sports, and other fields. In the field of medical materials, magnesium not only has the advantage of light weight, high strength, and a density similar to that of human bone, but also has good biocompatibility and promotes the growth of human bone. However, the mechanical properties and corrosion resistance of magnesium alloys need to be further improved to meet the requirements for human biodegradable implants. In this study, three alloys (mass fractions: Mg–10Zn, Mg–20Zn, and Mg–30Zn (wt.%)) were prepared using powder metallurgy by homogeneously mixing powders of the above materials in a certain amount with magnesium as the substrate through the addition of zinc elements, which also have good biocompatibility. The effect of zinc on the microstructure, mechanical properties, wear performance, and corrosion resistance of magnesium–zinc alloys was studied when the zinc content was different. The results show that compared with the traditional magnesium alloy using powder metallurgy, prepared magnesium alloy has good resistance to compression and bending, its maximum compressive stress can reach up to 318.96 MPa, the maximum bending strength reached 189.41 MPa, and can meet the mechanical properties of the alloy as a human bone-plate requirements. On the polarization curve, the maximum positive shift of corrosion potential of the specimens was 73 mv and the maximum decrease of corrosion-current density was 53.2%. From the comparison of the above properties, it was concluded that the three prepared alloys of which Mg–20% Zn had the best overall performance. Its maximum compressive stress, maximum bending strength, and corrosion-current density reached 318.96 MPa, 189.41 MPa and 2.08 × 10−5 A·cm−2 respectively, which are more suitable for use as human implant bone splints in human-body fluid environment.

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 .

Corrosion Resistance of Mg-4Zn Alloy with Amorphous Micro-Arc Oxidation Coating in Simulated Body Fluid

2016 ◽  
Vol 852 ◽  
pp. 1325-1333
Author(s):  
Li Chen Zhao ◽  
Shuang Jin Liu ◽  
Yu Min Qi ◽  
Chun Xiang Cui
Keyword(s):  
Corrosion Resistance ◽  
Simulated Body Fluid ◽  
Current Density ◽  
Polarization Resistance ◽  
Body Fluid ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Metal Substrate ◽  
Electrochemical Measurements ◽  
Micro Arc Oxidation

A binary Mg-4Zn alloy was fabricated as a potential degradable biomaterial. To improve the corrosion resistance of Mg-4Zn alloy, an amorphous micro-arc oxidation (MAO) coating was prepared on the Mg-4Zn substrate. Electrochemical measurements and immersion tests were employed to evaluate the corrosion resistance of the specimen in simulated body fluid (SBF). Electrochemical measurements show that the Mg-4Zn alloy covered with a MAO coating has a much lower corrosion current density and a much greater polarization resistance. Immersion tests suggest that the degradation of Mg-4Zn substrate is relatively serious during the initial 8 h of immersion although it has been protected by a MAO coating. When most micro-pores within the MAO coating have been filled with precipitates resulted from the corrosion of the metal substrate, the degradation of the Mg-4Zn substrate is significantly delayed.

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.

Study on Corrosion Property of Fluoride Treated Biodegradable AZ31 Magnesium Alloy

2013 ◽  
Vol 750-752 ◽  
pp. 1669-1673
Author(s):  
Chun Yan Zhang ◽  
Yan Long Ma ◽  
Cheng Long Liu
Keyword(s):  
Magnesium Alloy ◽  
Hydrogen Evolution ◽  
Hydrofluoric Acid ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Property ◽  
Conversion Coating ◽  
Az31 Magnesium Alloy ◽  
Coated Sample ◽  
Electrochemical Technique

In order to improve the corrosion resistance of Mg alloys as degradable implant material, fluorine conversion coatings were synthesized on AZ31 magnesium alloy by immersion in hydrofluoric acid (HF) for different time. Potentiodynamic electrochemical technique and hydrogen evolution testing were employed to investigate the corrosion behavior of the coated alloys in Hanks solution. It is indicated that the fluoride conversion coating, which is compact and composed of MgF2, can significantly decrease the degradation rate of Mg alloy AZ31 in Hanks solution. The most improved corrosion protection was achieved by immersion for 10 days. The corrosion current density was 40 times lower than that of the substrate and the hydrogen evolution rate of the coated sample was only one-fiftieth of the substrate.

Effect of Frequency and Duty Cycle on Growth, Structure and Corrosion Resistance of Micro Arc Oxidation Coating on RZ5 Magnesium Alloy

2018 ◽  
Vol 775 ◽  
pp. 291-297
Author(s):  
V. Ram Kumar ◽  
V. Muthupandi ◽  
K. Sivaprasad ◽  
P. Bala Srinivasan
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Duty Cycle ◽  
Oxide Coating ◽  
Constant Current ◽  
Constant Current Density ◽  
Duty Cycles ◽  
Micro Arc Oxidation ◽  
Surface Modification Techniques

Magnesium alloys inherently possess poor corrosion resistance. One of the surface modification techniques to improve the corrosion resistance of magnesium alloys is Micro Arc Oxidation (MAO). Application of RZ5 magnesium alloy in aircraft industries demands assured corrosion resistance of RZ5. The quality of the ceramic oxide coating developed by MAO is influenced by various operating parameters. In this study, oxide coatings on RZ5 Magnesium alloy were developed by MAO at two different frequency levels (100Hz and 1000Hz) and at two duty cycles (10% and 90%) at a constant current density of 0.06A/cm2 for 15 minutes in a silicate based electrolyte (10g/l Na2SiO3.9H2O + 4g/l KOH). Results showed that the coating produced with the combination of higher frequency and lower duty cycle exhibits a better corrosion resistance than the coating produced with other combinations of parameters.

Effects of CeO2 on Microstructure and Corrosion Performance of the Coatings Prepared by Pulse Micro Arc Oxidation on AZ31B Mg Alloy

2020 ◽  
Vol 20 (8) ◽  
pp. 4778-4786
Author(s):  
Lilu Qin ◽  
Jiamu Huang ◽  
Longlong Hao ◽  
Jun Su ◽  
Niu Ma ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Salt Spray ◽  
Electrochemical Measurement ◽  
Corrosion Current ◽  
Corrosion Performance ◽  
Micro Arc Oxidation ◽  
Micro Morphology

To improve corrosion performance of coatings on AZ31B magnesium alloy, the nano-CeO2 additives were included in Na2SiO3 based electrolyte during process of pulse micro arc oxidation (MAO). The MAO-CeO2 coating was successfully prepared to characterize its structure, micro morphology and composition. The XRD results indicated that MAO-CeO2 coatings were consisted of Mg2SiO4, MgSiO3, MgF2 and CeO2. The intensity of CeO2 peaks increases with increasing nano-CeO2 particles in electrolyte. The number of cracks on MAO-CeO2 coatings exhibited a V-shaped trend with increase in nano-CeO2 content. Meanwhile, the influence of nano-CeO2 on corrosion behavior of MAO-CeO2 coatings is investigated by salt spray test and electrochemical measurement. The corrosion current density of coatings presented same trend and corrosion potential is further studied. The MAO-CeO2 coatings formed in electrolyte with 10 g/L nano-CeO2 showed best corrosion performance which has the lowest corrosion current density of 0.58 nA/cm2 and the highest corrosion potential of - 1269 mVSCE.

scholarly journals The Corrosion Resistance of Graphene-Modified Oily Epoxy Coating on AZ31 Magnesium Alloys

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhengyuan Gao ◽  
Chengjin Sun ◽  
Lianteng Du ◽  
Dong Yang ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Epoxy Resin ◽  
Current Density ◽  
Corrosion Current Density ◽  
Surface Defects ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosive Media ◽  
Electrochemical Testing

In order to enhance the corrosion resistance of AZ31 magnesium alloy, graphene-modified oily epoxy resin coating (G/OEP) were prepared on the surface of magnesium alloy. SEM observations show that graphene has fewer surface defects, and can significantly improve the surface quality of the coating and reduce defects. FI-TR testing shows that coating are mainly composed of epoxy resin (polyurethane) and its corresponding curing agent. Electrochemical testing shows that the coating can provide good corrosion protection for magnesium alloy. Compared with the corrosion current density of magnesium alloy of 6.20 × 10−7 A/cm2, the G/OEP can significantly reduce the corrosion current density to 6.96 × 10−12 A/cm2. Analysis of the morphology of the coating after electrochemical corrosion found that graphene can improve the shielding ability of the coating to corrosive media, and reduce the damage of corrosion to the coating structure, and enhance the corrosion resistance of the coating. The content of graphene for excellent corrosion resistance of coating during this experiment is 0.6 wt%. The graphene can fill the defects generally in the coating during the curing process to prevent substrate from penetration of corrosive media caused by the density and hydrophobicity of coating are increased.

scholarly journals Evaluation of the Corrosion Resistance and Cytocompatibility of a Bioactive Micro-Arc Oxidation Coating on AZ31 Mg Alloy

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 396 ◽  
Author(s):  
Shun-Yi Jian ◽  
Mei-Ling Ho ◽  
Bing-Ci Shih ◽  
Yue-Jun Wang ◽  
Li-Wen Weng ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Protection ◽  
Treatment Time ◽  
Electrochemical Impedance ◽  
Oxide Coating ◽  
Constant Current ◽  
Micro Arc Oxidation

Magnesium alloys have recently been attracting attention as a degradable biomaterial. They have advantages including non-toxicity, biocompatibility, and biodegradability. To develop magnesium alloys into biodegradable medical materials, previous research has quantitatively analyzed magnesium alloy corrosion by focusing on the overall changes in the alloy. Therefore, the objective of this study is to develop a bioactive material by applying a ceramic oxide coating (magnesia) on AZ31 magnesium alloy through micro-arc oxidation (MAO) process. This MAO process is conducted under pulsed bipolar constant current conditions in a Si- and P-containing electrolyte and the optimal processing parameters in corrosion protection are obtained by the Taguchi method to design a coating with good anti-corrosion performance. The negative duty cycle and treatment time are two deciding factors of the coating’s capability in corrosion protection. Microstructure characterizations are investigated by means of SEM and XRD. The simulation body-fluid solution is utilized for testing the corrosion resistance with the potentiodynamic polarization and the electrochemical impedance test data. Finally, an in vivo testing shows that the MAO-coated AZ31 has good cytocompatibility and anticorrosive properties.

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