scholarly journals Effect of the second-step voltages on the structural and corrosion properties of silicon–calcium–phosphate (Si–CaP) coatings on Mg–Zn–Ca alloy

2018 ◽  
Vol 5 (10) ◽  
pp. 172410 ◽  
Author(s):  
Jinhe Dou ◽  
Yupeng Zhao ◽  
Lu Lu ◽  
Guochao Gu ◽  
Huijun Yu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Degradation Rate ◽  
Electrochemical Techniques ◽  
Orthopedic Implants ◽  
Mg Alloy ◽  
Second Step ◽  
Corrosion Properties ◽  
Slow Increase ◽  
Micro Arc Oxidation ◽  
Sbf Solution

The applications of magnesium (Mg) alloys as biodegradable orthopedic implants are mainly restricted due to their rapid degradation rate in the physiological environment. In this study, Si–CaP micro-arc oxidation (MAO) coatings were prepared on a Mg–Zn–Ca alloy by a second-step MAO process at different voltages in order to decrease the degradation rate and increase the bioactivity of the alloy. The microstructure and morphology of the samples were characterized using XRD, FT-IR SEM and EDS. The degradation behaviours of samples were evaluated using electrochemical techniques, and immersion tests in simulated body fluid (SBF). The results indicate that the morphology of the Si–CaP coatings changed significantly with the increase in Ca/P ratio as the second-step voltage increased. The Si–CaP containing coating produced at 450 V could significantly decrease the degradation rate of Mg and caused a slow increase in pH of the SBF solution. The haemolysis test concluded that the coating C3 did not cause a haemolytic reaction. The corrosion resistance of Mg alloy was greatly improved with the Si–CaP coatings, and the Mg alloy with Si–CaP coating prepared at 450 V had the best corrosion resistance, which indicates that the Si–CaP coatings are promising for improving the biodegradation properties of Mg-based orthopedic implants. Haemolysis tests indicated that the Si–CaP coating prepared at 450 V conforms to the given standard (YY/T0127.1-93).

Deposition time effects on structure and corrosion resistance of duplex MAO/Al coatings on AZ31B Mg alloy

2017 ◽  
Vol 64 (4) ◽  
pp. 357-364 ◽  
Author(s):  
Xue-Jun Cui ◽  
Ying-Jun Zhang ◽  
Bao-Jie Dou ◽  
Xian-Guang Zeng ◽  
Xiu-Zhou Lin
Keyword(s):  
Corrosion Resistance ◽  
Deposition Time ◽  
Mg Alloy ◽  
Structural Defects ◽  
Corrosion Properties ◽  
Corrosive Media ◽  
Combined Process ◽  
Content Type ◽  
Interfacial Compatibility ◽  
Micro Arc Oxidation

Purpose This paper aims to investigate the effects of deposition time on the structure and anti-corrosion properties of a micro-arc oxidation (MAO)/Al coating on AZ31B Mg alloy. Design/methodology/approach The study describes the fabrication of the coating via a combined process of MAO with multi-arc ion plating. The structure, composition and corrosion resistance of the coatings were evaluated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and electrochemical methods. Findings The Al-layer is tightly deposited with a good mechanical interlock along the rough interface due to the Al diffusion. However, the Al layer reduces the anti-corrosion of MAO-coated Mg alloy because of structural defects such as droplets and cavities, which act as channels for corrosive media infiltration towards the substrate. Fortunately, the Al layer improves the substrate corrosion resistance owing to its passive behaviour, and the corrosion resistance can be enhanced with increasing deposition time. All results indicate that a buffer layer fabricated through the duplex process improves the interfacial compatibility between the hard coating and soft Mg alloys. Originality/value An MAO/Al duplex coating was fabricated via a combined process of MAO and physical vapour deposition. MAO/Al duplex coatings exhibit obviously passive behaviours on AZ31 Mg alloy. The structure and corrosion resistance of MAO/Al coatings were investigated.

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.

scholarly journals Formation and Corrosion Resistance of Micro-Arc Oxidation Coating on Equal-Channel Angular Pressed AZ91D Mg Alloy

Metals ◽  
2016 ◽  
Vol 6 (12) ◽  
pp. 308 ◽  
Author(s):  
Aibin Ma ◽  
Fumin Lu ◽  
Qi Zhou ◽  
Jinghua Jiang ◽  
Dan Song ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Mg Alloy ◽  
Micro Arc Oxidation

scholarly journals Surface Modification of Mg0.8Ca Alloy via Wollastonite Micro-Arc Coatings: Significant Improvement in Corrosion Resistance

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 754
Author(s):  
Mariya B. Sedelnikova ◽  
Anna V. Ugodchikova ◽  
Tatiana V. Tolkacheva ◽  
Valentina V. Chebodaeva ◽  
Ivan A. Cluklhov ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Current ◽  
Biological Properties ◽  
Mineralization Process ◽  
Corrosion Properties ◽  
Oxidation Method ◽  
Significant Difference ◽  
Structure Phase ◽  
Micro Arc Oxidation ◽  
Calcium Silicates

Biodegradable materials are currently attracting the attention of scientists as materials for implants in reconstructive medicine. At the same time, ceramics based on calcium silicates are promising materials for bone recovery, because Ca2+ and Si2+ ions are necessary for the mineralization process, and they take an active part in the formation of apatite. In the presented research, the protective silicate biocoatings on a Mg0.8Ca alloy were formed by means of the micro-arc oxidation method, and the study of their morphology, structure, phase composition, corrosion, and biological properties was carried out. Elongated crystals and pores were uniformly distributed over the surface of the coatings. The coated samples exhibited remarkable anti-corrosion properties in comparison with bare magnesium alloy because their corrosion current decreased 10 times, and their corrosion resistance increased almost 100 times. The coatings did not significantly affect the viability of the cells, even without the additional dilution of the extract, and were non-toxic according to ISO 10993-5: 2009. In this case, there was a significant difference in toxicity of the pure Mg0.8Ca alloy and the coated samples. Thus, the results demonstrated that the applied coatings significantly reduced the toxicity of the alloy.

Ceramic Coatings of Magnesium Alloy for Biomaterial Applications

2010 ◽  
Vol 434-435 ◽  
pp. 634-637 ◽  
Author(s):  
Pu Liang Zhang ◽  
Bin Liu ◽  
Dong Zhang ◽  
Yong Wei Tao ◽  
Sheng Rong Yang ◽  
...  
Keyword(s):  
Body Fluid ◽  
Ceramic Coatings ◽  
Alkaline Treatment ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Electrodeposition Technique ◽  
Corrosion Properties ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Porous Oxide

Ceramic coatings were produced on magnesium (Mg) alloy of AZ91D for biomaterial applications by micro-arc oxidation (MAO) and electrodeposition methods. The morphology, microstructure, phase composition and corrosion properties of the prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and potentiodynamic polarization tester, etc. The results indicated that a porous oxide layer was grown on the Mg alloy sheets after MAO process and the compositions of oxides were mainly Mg2SiO4 and MgO. After further electrodeposition and alkaline treatment, a flake-like structure diverging from centre to periphery was grown on the MAO coating and the coating was mainly made up of hydroxyapatite (HA). Moreover, the corrosion resistance of the Mg alloy after being treated with MAO and electrodeposition technique increases obviously, which was evaluated in stimulated body fluid (SBF).

scholarly journals Effect of solid-solution and aging treatment on corrosion behavior of orthogonal designed and vacuum melted Mg-Zn-Ca-Mn alloys

2020 ◽  
Vol 18 ◽  
pp. 228080001988790 ◽  
Author(s):  
Dexue Liu ◽  
Tianshui Zhou ◽  
Zehua Liu ◽  
Bing Guo
Keyword(s):  
Solid Solution ◽  
Corrosion Resistance ◽  
Degradation Rate ◽  
Cast Alloy ◽  
Vacuum Induction Melting ◽  
Corrosion Properties ◽  
X Ray ◽  
Orthogonal Method ◽  
Heat Treated

Fast degradation rate and inhomogeneous corrosion are obstacles for magnesium alloy bio-corrosion properties. In this paper, a quaternary Mg-Zn-Ca-Mn alloy was designed by an orthogonal method and prepared by vacuum induction melting to investigate its bio-corrosion. Microstructure, corrosion morphology, and bio-corrosion properties of as-cast alloys 1 to 5 with good corrosion resistance were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction with immersion and electrochemical tests in simulated body fluid (SBF), respectively. Both the orthogonal method and in vitro degradation experiments demonstrated that alloy 3 exhibited the lowest degradation rate among the tested quaternary Mg-Zn-Ca-Mn alloys. Then, as-cast alloy 3 was treated by solid-solution and solid-solution aging. In vitro experimental results indicated that as-cast alloy 3 showed better corrosion resistance than heat-treated specimens and the average corrosion rate was approximately 0.15 mm/y. Heat-treated alloy 3 exhibited more uniform corrosion than as-cast alloy specimens. These results suggest that alloy 3 has the potential to become a biodegradable candidate material.

scholarly journals Influence of Cu2+ Ions on the Corrosion Resistance of AZ31 Magnesium Alloy with Microarc Oxidation

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2647
Author(s):  
Madiha Ahmed ◽  
Yuming Qi ◽  
Longlong Zhang ◽  
Yanxia Yang ◽  
Asim Abas ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Photoelectron Spectroscopy ◽  
Microarc Oxidation ◽  
Mg Alloy ◽  
Cell Counting ◽  
Cytotoxicity Test ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
X Ray ◽  
Az31 Mg Alloy

The objectives of this study were to reduce the corrosion rate and increase the cytocompatibility of AZ31 Mg alloy. Two coatings were considered. One coating contained MgO (MAO/AZ31). The other coating contained Cu2+ (Cu/MAO/AZ31), and it was produced on the AZ31 Mg alloy via microarc oxidation (MAO). Coating characterization was conducted using a set of methods, including scanning electron microscopy, energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and X-ray diffraction. Corrosion properties were investigated through an electrochemical test, and a H2 evolution measurement. The AZ31 Mg alloy with the Cu2+-containing coating showed an improved and more stable corrosion resistance compared with the MgO-containing coating and AZ31 Mg alloy specimen. Cell morphology observation and cytotoxicity test via Cell Counting Kit-8 assay showed that the Cu2+-containing coating enhanced the proliferation of L-929 cells and did not induce a toxic effect, thus resulting in excellent cytocompatibility and biological activity. In summary, adding Cu ions to MAO coating improved the corrosion resistance and cytocompatibility of the coating.

Corrosion Characterization of Titanium Alloys by Electrochemical Techniques in Artificial Saliva and SBF Solution

2008 ◽  
Vol 396-398 ◽  
pp. 315-318 ◽  
Author(s):  
Neide A. Mariano ◽  
Rafael G. Oliveira ◽  
E.I. Braga ◽  
E.C.S. Rigo
Keyword(s):  
Corrosion Resistance ◽  
Artificial Saliva ◽  
Electrochemical Techniques ◽  
Pure Titanium ◽  
Protective Film ◽  
Commercially Pure Titanium ◽  
Passive Region ◽  
Sbf Solution ◽  
Cp Ti

The commercially pure titanium (cp Ti) biocompatibility is due to its chemical stability in organism because of the presence of a fine film and impermeable of titanium oxide over the metal surface that confirms its corrosion resistance, changing this material's surface has been the direction of many research groups, these modifications may have influence in corrosion resistance. In this work was investigated the electrochemical behavior of cp Ti, without and with coating of the hydroxyapatite, commonly used implant materials, in artificial saliva and simulated body fluid (SBF) solution at 25oC and pH=7.4. The potentiodynamic polarization curves, shows that there is a passive region with low current’ density, indicating that in the investigated conditions the formation of a surface protective film occurs. In the studied conditions it was observed that hydroxyapatite layer has influence on corrosion resistance properties.

Micro Arc Oxidation of AZ91 Mg Alloy for Improved Corrosion Resistance

2011 ◽  
Vol 312-315 ◽  
pp. 877-881 ◽  
Author(s):  
H.G. Yavuz ◽  
M. Gunyuz ◽  
Isa Metin Ozkara ◽  
Murat Baydogan ◽  
Huseyin Cimenoglu
Keyword(s):  
Corrosion Resistance ◽  
Surface Topography ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Corrosive Solution ◽  
Weight Losses ◽  
Before And After ◽  
Micro Arc Oxidation

AZ91 Mg alloy was subjected to the micro arc oxidation process by using different processing parameters. Following oxidation, surface topography and qualitative phase analysis were made by tabletop digital microscopy and X-ray diffraction (XRD) analysis. In order to evaluate the relative corrosion resistance of the samples that were oxidized in different parameters, the samples were immersed in a corrosive solution for 6 days and the weight losses before and after the corrosion tests were compared. Relative corrosion resistance of the samples was evaluated on the basis of surface topography.

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