Effect of Impulse Voltage on Microstructure and Corrosion Resistance of Microarc Oxidation Coatings on AZ80 Magnesium Alloy

2013 ◽  
Vol 575-576 ◽  
pp. 418-422 ◽  
Author(s):  
Jie Ma ◽  
Yuan Sheng Yang ◽  
Xiu Chun Wang ◽  
Jing Zhang ◽  
Shuo Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Current Density ◽  
Microarc Oxidation ◽  
Corrosion Current ◽  
Spot Test ◽  
Pulse Voltage ◽  
Oxidation Treatment ◽  
Az80 Magnesium Alloy ◽  
Structure Surface

Microarc oxidation coating and microarc oxidation-fluorocarbon coating were prepared on the surface of AZ80 magnesium alloy profiles. The phase structure, surface morphology and corrosion resistance of the coatings were investigated using SEM, XRD, copper sulfate spot test and polarization curve test. The main phase compositions of the microarc oxidation coatings were MgO, Mg2SiO4, MgSiO3, MgF2 and MgAl2O4. With increasing pulse voltage, the oxidation coating became thicker and the microstructure of the coating surface became compact; therefore the coating corrosion resistance was improved. The oxidation coating with pulse voltage of microarc oxidation controlled between 300-438V obtained the best corrosion resistance. The corrosion current density of magnesium alloy reduced 1-3 orders of magnitude after microarc oxidation treatment with increasing pulse voltage, and the corrosion resistance of microarc oxidation-fluorocarbon coating is desirable.

Microstructure and Corrosion Resistance of Microarc Oxidation Coatings on AZ31 Magnesium Alloy Extrusion Profiles

2012 ◽  
Vol 557-559 ◽  
pp. 1993-1997
Author(s):  
Jie Ma ◽  
Yuan Sheng Yang ◽  
Xiu Chun Wang ◽  
Jing Zhang ◽  
Shuo Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Microarc Oxidation ◽  
Corrosion Current ◽  
Spot Test ◽  
Pulse Voltage ◽  
Az31 Magnesium Alloy ◽  
Oxidation Treatment ◽  
Coating Surface ◽  
Structure Surface

Microarc oxidation coatings were prepared on the surface of AZ31 magnesium alloy profiles. Oxidation time of the coatings was between 5min-10min. The phase structure, surface morphology and corrosion resistance of the coatings were investigated using SEM, XRD, copper sulfate spot test and polarization curve test. The results indicate: the main phase compositions of the microarc oxidation coatings are MgO, Mg2SiO4 and MgSiO3; with increasing pulse voltage, the micropore diameter of the coating surface becomes larger, the micropore number reduces and the coating surface roughness increases; the corrosion current density of magnesium alloy reduces significantly after microarc oxidation treatment. The pulse voltage of microarc oxidation should be controlled between 240V-360V to obtain the best corrosion resistance.

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.

Effects of Voltage on the Characteristics and Corrosion Resistance of Microarc Oxidation Coatings on Ti6Al4V Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 1336-1339
Author(s):  
Zong Chun Hu ◽  
Fa Qin Xie ◽  
Xiang Qing Wu
Keyword(s):  
Aqueous Solution ◽  
Corrosion Resistance ◽  
Corrosion Current Density ◽  
Turning Point ◽  
Electrochemical Impedance ◽  
Microarc Oxidation ◽  
Corrosion Current ◽  
Ceramic Coatings ◽  
Thickness Gauge ◽  
Potentiostatic Regime

Ceramic coatings were prepared on Ti6Al4V in aluminate-based electrolyte by microarc oxidation at various voltages using potentiostatic regime. The phase composition, microstructure and morphology of the coatings were characterized by eddy thickness gauge, XRD and SEM respectively. The corrosion resistance of the coatings was investigated by polarization curve and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl aqueous solution. The results show that all the coatings are mainly composed of Al2TiO5. When the voltage increases from 360V to 510V, the coating thickness grows significantly, and the pores in the coatings get large and deep simultaneously. As a result, the corrosion resistance of the coatings increases first and then decreases with the turning point of 410V, at which the coating prepared shows the smallest corrosion current density of 1.965E-9 A/cm2. The coating prepared at a higher voltage before the discharges grow large and intense (410V in this work) shows the best corrosion resistance.

Effect of Negative Pulse Voltage on the Microstructure and Corrosion Resistance of Microarc Oxidation Film of A356 Aluminum Alloy

2011 ◽  
Vol 675-677 ◽  
pp. 1193-1196 ◽  
Author(s):  
Guang Huai Peng ◽  
Bao Jun Han ◽  
Ling Fang ◽  
Xue Feng Guo ◽  
Xiao Lian Zhang
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Microarc Oxidation ◽  
Film Surface ◽  
Corrosion Current ◽  
Pulse Voltage ◽  
Thickness Gauge ◽  
A356 Aluminum Alloy ◽  
Negative Pulse ◽  
A356 Aluminum

The effect of negative pulse voltage on the microstructure and corrosion resistance of microarc oxidation film of A356 aluminum alloy treated by microarc technique was investigated by SEM, coating thickness gauge and electrochemical workstation etc. The results show the negative pulse voltage greatly influences the microstructure and corrosion resistance of microarc oxidation film by its electrode reaction. The film thickness increases while the size of pore and roughness of the film surface decreases initially and then increases with negative pulse voltage increasing. The microarc oxidation treatment considerably improved corrosion resistance, and the highest corrosion potential was -1.16V, which was 0.38V higher than that of substrate, and the corrosion current was lower than that of substrate about three orders of magnitude.

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 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 The Corrosion Resistance of Al Film on AZ31 Magnesium Alloys by Magnetron Sputtering

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1522
Author(s):  
Zhengyuan Gao ◽  
Dong Yang ◽  
Chengjin Sun ◽  
Lianteng Du ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnetron Sputtering ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Aluminum Film ◽  
Dc Magnetron Sputtering ◽  
Excellent Corrosion Resistance ◽  
Micro Cracks ◽  
Sputtering Power

Nano Al films were prepared on AZ31 magnesium alloy samples by DC magnetron sputtering. The effects of sputtering power on the microstructure and corrosion resistance of the Al film were investigated. The results show that the surface of aluminum film is dense and polycrystalline state, and it is oriented along the Al (111) crystal plane. The grain size of Al film first increases and then decreases with the increase of sputtering power. When the sputtering power exceeds 100 W, there is no insignificant effect on the orientation of the Al crystals and the corrosion current density of the samples with Al film are reduced by two orders of magnitude. The corrosion resistance of the magnesium alloy samples with the Al film magnetron sputtered varies with the sputtering power. Compared with low sputtering power, the Al film sputtered by high power has the most excellent corrosion resistance, but too high sputtering power will lead to micro cracks on the Al film, which will adversely affect the corrosion resistance.

A Study on the Electroless Ni–P Deposition of AM60B Magnesium Alloy without HF in Bath

2014 ◽  
Vol 633-634 ◽  
pp. 879-882 ◽  
Author(s):  
Jing Dong Qiu ◽  
Su Qiu Jia
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Electroless Nickel ◽  
Corrosion Current ◽  
Dense Structure ◽  
Electroless Ni

Based on the traditional direct electroless nickel methods, chemical baths are improved by removing HF. Examinations have been carried out on the Ni-P deposited on the interlayer for morphology, composition and corrosion-resistance by SEM, EDS, XRD and other instruments. A Ni-P film with fine and dense structure was obtained on the AM60B magnesium alloy. It exhibits lower corrosion current density and more positive corrosion potential than the substrate.

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.

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