Structure, corrosion resistance and apatite-forming ability of NiTi alloy treated by micro-arc oxidation in concentrated H2SO4

Microarc oxidation coatings on biomedical NiTi alloy were prepared in aluminate electrolytes with and without hypophosphate addition. The effect of hypophosphate concentrations on the characteristics of micro-arc oxidation coatings has been studied. The compositions and surface morphologies of the coatings prepared in different hypophosphate concentrations were determined by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Surface roughness (Ra) and bonding strength of the coatings were measured by surface roughmeter and a direct pull-off test, respectively. The corrosion resistance of the coatings was evaluated in Hank’s solution using potentiodynamic polarization tests. The results show that all of the coatings exhibit a typical porous surface structure and mainly consist of γ-Al2O3 crystal phase. With increasing the hypophosphate concentrations, the elemental contents of Ni, Ti and P increase while Al decreases; the pore sizes and surface roughness of the coatings decrease firstly, reaching a minimum value at 0.01mol/L, and then increase; at the same time, the bonding strength increases up to 60MPa, and then decreases. The corrosion resistance of the coatings decreases with the increase of the hypophosphate concentrations, but all of the coated samples is better than that of the uncoated NiTi alloy.

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The corrosion resistance behavior of Al2O3 coating prepared on NiTi alloy by micro-arc oxidation

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2008.04.064 ◽

2009 ◽

Vol 472 (1-2) ◽

pp. 276-280 ◽

Cited By ~ 51

Author(s):

J.L. Xu ◽

F. Liu ◽

F.P. Wang ◽

D.Z. Yu ◽

L.C. Zhao

Keyword(s):

Corrosion Resistance ◽

Niti Alloy ◽

Al2o3 Coating ◽

Micro Arc Oxidation

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A Preliminary Study of Anodization and Electroless Ni–P Plating on AZ80 Magnesium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.299-300.663 ◽

2011 ◽

Vol 299-300 ◽

pp. 663-666 ◽

Cited By ~ 1

Author(s):

Ping Shi ◽

Xue Dong Han

Keyword(s):

Corrosion Resistance ◽

Magnesium Alloy ◽

Weight Ratio ◽

High Strength ◽

Surface Modifications ◽

Atomic Ratio ◽

Az80 Magnesium Alloy ◽

Micro Arc Oxidation ◽

Preliminary Study ◽

Electroless Ni

Magnesium alloys are being used as structural components in industry because of their high strength to weight ratio. But their high electrochemical activity and poor corrosion resistance limited their applications. Therefore, surface modifications are needed for protection purpose. This paper studied the anodic micro-arc oxidation and electroless Ni-P plating surface modifications on AZ80 magnesium alloy. The SEM, XRD and EDS were used to characterize the surface coating. It shows that a micro-porous MgO layer with the pores size 5 – 20 μm was fabricated on the bare magnesium alloy. The nodule Ni-P deposition could be prepared on the out layer of MgO with Ni/P atomic ratio being 1.4. The pores in MgO layer could be sealed by the following Ni-P deposition. Therefore the corrosion resistance of the magnesium alloy could be further improved.

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Enhanced uniformity, corrosion resistance and biological performance of Cu-incorporated TiO2 coating produced by ultrasound-auxiliary micro-arc oxidation

Applied Surface Science ◽

10.1016/j.apsusc.2021.150932 ◽

2021 ◽

pp. 150932

Author(s):

Xinxin Zhang ◽

Tong Zhang ◽

You Lv ◽

Yupeng Zhang ◽

Xueqin Lu ◽

...

Keyword(s):

Corrosion Resistance ◽

Tio2 Coating ◽

Micro Arc Oxidation ◽

Biological Performance

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Structure and Resistance to Electrochemical Corrosion of NiTi Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.203-204.335 ◽

2013 ◽

Vol 203-204 ◽

pp. 335-338 ◽

Cited By ~ 2

Author(s):

Bożena Łosiewicz ◽

Magdalena Popczyk ◽

Tomasz Goryczka ◽

Józef Lelątko ◽

Agnieszka Smołka ◽

...

Keyword(s):

Corrosion Resistance ◽

Niti Alloy ◽

Electrochemical Corrosion ◽

High Resolution Electron Microscopy ◽

Potential Method ◽

Passive Layer ◽

Open Circuit ◽

Experimental Conditions ◽

Electrochemical Tests ◽

Reflectivity Method

The NiTi alloy (50.6 at.% Ni) passivated for 30 min at 130°C by autoclaving has been studied towards corrosion resistance in aqueous solutions of 3% NaCl, 0.1 M H2SO4, 1 M H2SO4 and HBSS. Structure and thickness of the passive layer (TiO2, rutile) were examined by X-ray reflectivity method and high resolution electron microscopy. Corrosion behavior of this oxide layer was investigated by open circuit potential method and polarization curves. It was found that the corrosion resistance of the passivated NiTi alloy is strongly dependent on the type of corrosive environment. The higher corrosion resistance of the tested samples was revealed in sulfate solutions as compared to chloride ones. The highest resistance to electrochemical corrosion of the NiTi alloy was observed in 0.1 M H2SO4 solution. Susceptibility to pitting corrosion of the tested samples was observed which increased with the concentration rise of chlorine anions in solution. Electrochemical tests for 316L stainless steel carried out under the same experimental conditions revealed a weaker corrosion resistance in all solutions as compared to the highly corrosion resistant NiTi alloy.

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Preparation and Characterization of a Sol–Gel AHEC Pore-Sealing Film Prepared on Micro Arc Oxidized AZ31 Magnesium Alloy

Metals ◽

10.3390/met11050784 ◽

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.

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