scholarly journals Effect of Micro-arc Oxidation Time on Corrosion Resistance of Magnesium Alloys

2020 ◽  
Vol 1570 ◽  
pp. 012044
Author(s):  
Shihao Li ◽  
Xin Liu ◽  
Shengjun Liu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Oxidation Time ◽  
Micro Arc Oxidation

Effects of NaOH Concentration on Properties of Micro Arc Coatings on Magnesium Alloys

2012 ◽  
Vol 482-484 ◽  
pp. 909-913 ◽  
Author(s):  
Shu Fang Zhang ◽  
Rong Fa Zhang ◽  
Wen Kui Li ◽  
Yi Min Zhong
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Magnesium Alloys ◽  
Environmental Scanning ◽  
Nacl Solution ◽  
Base Solution ◽  
Polarization Test ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Anodic coatings were prepared by micro arc oxidation on AZ91HP in a base solution of 18 g/L Na2SiO3 ּ9H2Oand 4 g/L tannic acid with 5-20 g/l NaOH. The influence of NaOH concentration on final voltage and corrosion resistance were studied. The morphologies of anodic coatings were determined by environmental scanning electron microscope (ESEM). Potentiodynamic polarization test was performed in 3.5wt.% NaCl solution to evaluate the corrosion resistance of anodic coatings. The results show that the NaOH concentration has greatly effect on the final voltage, the compositions, thickness, morphologies and corrosion resistance. The corrosion resistance of anodic coatings is the best in the base solution containing 10 g/l NaOH.

scholarly journals Corrosion Resistance of Micro-Arc Oxidation/Graphene Oxide Composite Coatings on Magnesium Alloys

ACS Omega ◽  
2020 ◽  
Vol 5 (13) ◽  
pp. 7262-7270 ◽  
Author(s):  
Wei Shang ◽  
Fang Wu ◽  
Yuanyuan Wang ◽  
Amin Rabiei Baboukani ◽  
Yuqing Wen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Graphene Oxide ◽  
Magnesium Alloys ◽  
Composite Coatings ◽  
Oxide Composite ◽  
Micro Arc Oxidation

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.

Growth Process and Corrosion Resistance of Ceramic Coatings of Micro-Arc Oxidation on Mg-Nd Magnesium Alloys

2011 ◽  
Vol 189-193 ◽  
pp. 891-896
Author(s):  
Yong Chun Guo ◽  
Jian Ping Li ◽  
Jin Shan Li ◽  
Ping Wang
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Magnesium Alloys ◽  
Phase Structure ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Ceramic Surface ◽  
Linear Regularity ◽  
Micro Arc Oxidation

The regulation of ceramic coating formed by micro-arc oxidation on Mg-3Nd-0.2Zn-0.4Zr(wt%) magnesium alloys has been investigated by SEM and XRD. The relation of phase structure and corrosion resistance of MgO coating formed by micro-arc oxidation in different growth stages has been analyzed. The results have shown that in the initial stages of micro-arc oxidation, the growth of coating accords with linear regularity, which is the stage of anodic oxidation controlled by electrochemical polarization. With elongated treated time and increased thickness of the coating, the growth of coating accords with parabolic and linear regularity, which is the stage of micro-arc oxidation. In the stage of local arc light, the slope of parabola and thickness of loose coating increases so that the growth rate enhances. The phase structure of loose coating is mainly composed of MgSiO3 and the phase structure of compact ceramic coating is mainly composed of MgO. From the stage of micro-arc oxidation to local arc light, corrosion resistance of coating firstly increase and then decrease. The satisfied corrosion resistance corresponds to the coating time ranging from 7 to15minutes.The addition of rare earth elements in the magnesium alloy reduces the amount of smooth areas on ceramic surface. So the ceramic coating becomes more compact and smooth. The rare earth elements don’t form independent phases in ceramic coating but affect the relative proportion of constitution phases, resulting in the reduction of intermixed magnesium phase and the increase of the MgO and MgSiO3 phases.

Growth process and corrosion resistance of micro-arc oxidation coating on Mg-Zn-Gd magnesium alloys

2010 ◽  
Vol 20 (11) ◽  
pp. 2198-2203 ◽  
Author(s):  
Ping WANG ◽  
Dao-xin LIU ◽  
Jian-ping LI ◽  
Yong-chun GUO ◽  
Zhong YANG
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Growth Process ◽  
Micro Arc Oxidation

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.

Influences of Tannic Acid Concentration on Properties of Micro-Arc Coatings Formed on AZ91 Magnesium Alloys

2012 ◽  
Vol 182-183 ◽  
pp. 297-301
Author(s):  
Shu Fang Zhang ◽  
Rong Fa Zhang ◽  
Tao Wang ◽  
Shun Shun Yao ◽  
Zhi Hua Chen
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Acid Concentration ◽  
Tannic Acid ◽  
Coating Properties ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium ◽  
Solution Conductivity ◽  
Coating Color

Anodic coatings were prepared by micro-arc oxidation on AZ91 magnesium alloys with the addition of 0-8 g/L tannic acid. The influences of tannic acid concentration on the conductivity and coating properties were studied. The result shows that with the increase of tannic acid concentration, the solution conductivity decreases and the coating color becomes dark. In the solution with 4 g/L tannic acid, the obtained coatings are the most uniform and achieve the best corrosion resistance.

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.

Preparation and Corrosion Behaviour of Micro-Arc Oxidation Coating on Ti6Al4V Alloy

2012 ◽  
Vol 621 ◽  
pp. 117-120
Author(s):  
Xiu Zhou Lin ◽  
Min Gong ◽  
Zhao Hua Wang ◽  
Peng Zhang
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Potential ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Corrosion Current ◽  
Ti6al4v Alloy ◽  
Oxidation Time ◽  
Oxidation Treatment ◽  
X Ray ◽  
Micro Arc Oxidation

Micro-arc oxidation (MAO) coatings were prepared on Ti6Al4V alloys surface by using self-made micro-arc oxidation equipment. Its characterizations were systematically detected by Vickers hardness tester, scanning electron microscope (SEM), X-ray diffractometer (XRD) and X-ray fluorescence spectrometer (XFS). Corrosion behaviour of MAO coating and Ti6Al4V alloy in Hank's simulated body fluid were studied comparatively using electrochemical workstations and salt spray test chamber. The experimental results indicated that the MAO coating, with rough surface, high hardness and typical porous ceramic structure, is mainly consist of anatase and rutile TiO2 phase. Micro-arc oxidation treatment can significantly improve corrosion resistance of Ti6Al4 alloy, and the corrosion resistance of the coating is observably affected by the coating technology. During the micro-arc oxidation treatment, the thickness of the coating increases with the increase of oxidation time, which induce that the corrosion potential and polarization resistance of the coating increase, and the corrosion current reduce. Simultaneously, the thicker the coating, the higher the pitting resistance is. On the other hand, under the same oxidation time, as the current density increases during micro-arc oxidation treatment, the corrosion potential of the coating positive shifts, and the corrosion current reduces.

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