scholarly journals Study of the Effect of Current Pulse Frequency on Ti-6Al-4V Alloy Coating Formation by Micro Arc Oxidation

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3983 ◽  
Author(s):  
Alexander Sobolev ◽  
Alexey Kossenko ◽  
Konstantin Borodianskiy
Keyword(s):  
Corrosion Resistance ◽  
Oxide Coating ◽  
Alloy Coating ◽  
Pulse Frequency ◽  
Porous Coating ◽  
Cross Sectional ◽  
Current Frequency ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Porous Morphology

The micro arc oxidation (MAO) process has been applied to produce ceramic oxide coating on Ti-6Al-4V alloy. The MAO process was carried out at the symmetric bipolar square pulse in electrolyte containing Na2CO3 and Na2SiO3. The effect of current frequency on the surface morphology, the chemical and the phase compositions as well as the corrosion resistance was examined. Morphology and cross-sectional investigation by electron microscopy evaluated more compacted and less porous coating produced by high current frequency (1000 Hz). This alloy also exhibited a high corrosion resistance in comparison with the untreated alloy. Additionally, the alloy subjected to MAO treatment by a current frequency of 1000 Hz showed a higher corrosion resistance in comparison with alloys obtained by lower current frequencies. This behavior was attributed to more compacted and less porous morphology of the coating.

scholarly journals Coating Formation on Ti-6Al-4V Alloy by Micro Arc Oxidation in Molten Salt

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1611 ◽  
Author(s):  
Alexander Sobolev ◽  
Israel Wolicki ◽  
Alexey Kossenko ◽  
Michael Zinigrad ◽  
Konstantin Borodianskiy
Keyword(s):  
Corrosion Resistance ◽  
Protective Coatings ◽  
Oxide Coating ◽  
Resistance Testing ◽  
Morphological Examination ◽  
Protective Oxide ◽  
Coating Morphology ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Electrochemical Surface Treatment

Micro Arc Oxidation (MAO) is an electrochemical surface treatment process to produce oxide protective coatings on some metals. MAO is usually conducted in an aqueous electrolyte, which requires an intensive bath cooling and leads to the formation of a coating containing impurities that originate in the electrolyte. In the current work, we applied an alternative ceramic coating to the Ti-6Al-4V alloy using the MAO process in molten nitrate salt at a temperature of 280 °C. The obtained coating morphology, chemical and phase composition, and corrosion resistance were investigated and described. The obtained results showed that a coating of 2.5 µm was formed after 10 min of treatment, containing titanium oxide and titanium‒aluminum intermetallic phases. Morphological examination indicated that the coating is free of cracks and contains round, homogeneously distributed pores. Corrosion resistance testing indicated that the protective oxide coating on Ti alloy is 20 times more resistive than the untreated 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.

Corrosion and Wear Protection through Micro Arc Oxidation Coatings in Aluminum and Its Alloys

2019 ◽  
Author(s):  
L. Rama Krishna ◽  
G. Sundararajan
Keyword(s):  
Corrosion Resistance ◽  
Surface Properties ◽  
High Hardness ◽  
Basic Mechanism ◽  
Industrial Applications ◽  
Corrosion Properties ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Wear And Corrosion Resistance ◽  
Technological Limitations

This article presents the brief overview of fairly recent and eco-friendly micro arc oxidation (MAO) coating technology. The weight-cost-performance benefits in general raised the interest to utilize lightweight materials, especially the aluminum and its alloys. Despite numerous engineering advantages, the aluminum alloys themselves do not possess suitable tribology and corrosion resistance. Therefore, improvements in surface properties are essential to enable developing potential industrial applications. For improving wear and corrosion resistance of Al alloys, the most demanding surface properties are high hardness and chemical inertness. The technical and technological limitations associated with traditional anodizing and hard anodizing processes have been the strongest driving force behind the development of new MAO technology. While presenting the key technological elements associated with the MAO process, the basic mechanism of coating formation and its phase gradient nature is presented. Influence of various process parameters including the electrolyte composition has been discussed. The typical microstructural features and distribution of α- and γ-Al2O3 phases across the coating thickness as a key strategy to form dense coatings with required mechanical, tribological, and corrosion properties which are vital to meet potential application demands are briefly illustrated.

Study On the Corrosion Resistance Properties of the Ceramic Coating Obtained Through Microarc Oxidation on the Aluminium Alloy Surface

2007 ◽  
Vol 353-358 ◽  
pp. 1733-1736 ◽  
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Chen Chen ◽  
Fan Xiu Lu ◽  
Fan Xiu Lu
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Electrochemical Corrosion ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Α Al2o3

Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5% NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation was investigated too.

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.

Coating Structure and Corrosion Resistance Behavior of Hot Dip Zn-Al-Mg-Si Alloy Coating Steel Sheet

2013 ◽  
Vol 834-836 ◽  
pp. 601-608 ◽  
Author(s):  
She Ming Jiang ◽  
Chong Feng Yue ◽  
Qi Fu Zhang
Keyword(s):  
Corrosion Resistance ◽  
Steel Sheet ◽  
Salt Spray ◽  
Alloy Coating ◽  
Coated Steel ◽  
Coating Structure ◽  
Cross Sectional ◽  
Coating Technology ◽  
Coated Steel Sheet ◽  
Metal Materials

Hot Dip Zn-6Al-3Mg-0.2Si coating steel sheet was prepared in laboratory by Hot-dip Galvanizing Simulator produced by National Engineering Lab of Advanced Coating Technology for Metal Materials. The surface and cross sectional microstructure of the samples were analyzed by using SEM and EDS. Hot dip Zn coated, 55Al-43.3Zn-1.6Si and Zn-6Al-3Mg-0.2Si coated steel sheet samples were exposed to standardized salt spray test. The Zn-6Al-3Mg-0.2Si coating and its erode production were investigated by XRD. The results showed that the hot dip Zn-6Al-3Mg-0.2Si coating had better corrosion resistance than ordinary galvanized layer.

Biodegradable Behaviors in Simulated Body Fluid of Mg-Gd-Y-Zr Alloy with Micro-Arc Oxide Coating

2013 ◽  
Vol 747-748 ◽  
pp. 295-300
Author(s):  
Kai Yang Yin ◽  
Tian Feng Lu ◽  
Qing Dong ◽  
Bing Yi Sun ◽  
Bin Chen
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Oxide Coating ◽  
Volume Measurement ◽  
Before And After ◽  
Micro Arc Oxidation ◽  
Weight Loss Method ◽  
Loss Method

The effects of micro-arc oxidation (MAO) on corrosion resistance of Mg-Gd-Y-Zr magnesium alloy have been studied. The Mg-Gd-Y-Zr with thicker oxide coating presented higher corrosion resistance in simulated body fluid (SBF). The corrosion rates were measured by several methods including hydrogen evolution volume measurement, weight-loss method and determination of pH as an auxiliary reference. The surfaces of specimens were observed by SEM and white light confocal microscopy before and after the corrosion. Besides the effects of MAO, the pitting resulted from breakage of oxide coating played a notable role as well. This provided a new direction towards the enhancement of corrosion resistance of magnesium alloy.

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.

Effect of Processing Parameters on the Structural and Mechanical Properties of Micro Arc Oxidized Aluminium Alloy

2010 ◽  
Vol 297-301 ◽  
pp. 942-947
Author(s):  
Isa Metin Ozkara ◽  
Murat Baydogan
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Morphological Characterization ◽  
Cross Sectional ◽  
Wear And Corrosion ◽  
Thickness Gage ◽  
Micro Arc Oxidation ◽  
Wear And Corrosion Resistance

The micro arc oxidation process (MAO) was applied to a 2024 ingot aluminium alloy by an AC MAO equipment using an alkali based electrolyte. The processing parameters of the process were positive and negative voltage pulse durations. Structural and morphological characterization of the coating were made by a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a surface profilometer and a thickness gage operating according to the Eddy current principle. Cross sectional hardness of the coatings was measured, and reciprocating wear and immersion corrosion tests were performed. XRD analysis showed that an oxide layer comprising - and -Al2O3 phases was produced on the surface, whose thickness and surface roughness varied by the processing parameters applied. Wear and corrosion resistance of the original alloy significantly improved upon the MAO process. Variation of hardness, wear and corrosion resistance with respect to the processing parameters was discussed based on the experimental data obtained.

Role of Electric Pulse Duty and Frequency on Properties of Micro-Arc Oxidized Titania Films Developed on Ti-6Al-4V

2013 ◽  
Vol 765 ◽  
pp. 688-692
Author(s):  
K. Venkateswarlu ◽  
S. Suresh ◽  
N. Rameshbabu ◽  
D. Sreekanth ◽  
M. Sandhyarani
Keyword(s):  
Corrosion Resistance ◽  
Duty Cycle ◽  
Electric Pulse ◽  
Rutile Phase ◽  
Pulse Frequency ◽  
Oxidation Time ◽  
Biomedical Implant ◽  
Implant Material ◽  
Micro Arc Oxidation ◽  
Titania Films

The present work is mainly focussed on studying the effect of electric pulse frequency and duty cycle on the structural, morphological and corrosion characteristics of micro arc oxidation (MAO) films developed for a fixedoxidation timeof 2.5 min on Ti-6Al-4V biomedical implant material. For this purpose, the titania films are decisively developed under four different conditions arising from two levels of pulse duty cycle (10% and 75%) and frequencies (500 Hz and 1500 Hz). A phosphate based electrolyte system is employed for developing the titania films. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrated that though all the titania films are developed for the same oxidation time of 2.5 min, the rate of anatase to rutile phase transformation, the crystallite growth, the size and distribution of surface pores and film thickness of the titania film are strongly influenced by the electric pulse frequency and duty cycle. The potentiodynamic polarization (PDP) tests conducted under simulated body fluid (SBF) conditions (37 °C and 7.4 pH) showed that all the titania films could significantly improve the corrosion resistance of Ti-6Al-4V compared to that of the untreated alloy. Of all the titania films developed for the same oxidation time of 2.5 min, the one treated with 1500 Hz frequency and 75% duty cycle exhibited better corrosion resistance than those of the other films and the untreated Ti-6Al-4V implant material.

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