Electrolyte effect in pulsed anodization of NiTi alloy to form a Ni-free oxide layer

Yamasaki, Kako; Taniho, Hiroki; Tate, Kasumi; Ohtsu, Naofumi

doi:10.1016/j.surfcoat.2021.127221

Cited by 9 publications

(8 citation statements)

References 34 publications

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“…It is worthy commenting on the extent to which the present results compare with those of our previous test. 8) It should be noted that the Ni ion release test in the previous study was conducted using a shorter period of 24 h. The tendency for the Ni ions to be released seemed to be similar notwithstanding the length of the testing periods, but the difference among the samples in terms of the amount of Ni ions that are released is enhanced notably. These results indicate that the corrosion resistance as a result of pulsed anodization is enhanced in the case of a longer immersion period.…”

Section: Characteristics Of the Pulsed-anodized Niti Surfacesmentioning

confidence: 77%

“…Note that these XPS results were in agreement with the results of our previous study in which we compared the surface characteristics of the pulsedanodized NiTi alloy using various electrolytes. 8) The morphology of the anodized NiTi surface, observed by FE-SEM, is shown in Fig. 1.…”

Section: Characteristics Of the Pulsed-anodized Niti Surfacesmentioning

confidence: 99%

“…Additionally, the corrosion protective property of the H 2 SO 4 layer was superior to the anodized layer that was formed using the HNO 3 electrolyte: in fact, the release of Ni ions from the surface in the presence of H 2 SO 4 was approximately 1/3 of that of the HNO 3 surface. 8) These differences in the properties of the surface layer are likely to influence the activity of the ECs thereon; thus, selecting an adequate electrolyte for the pulsed anodization process is an important task. Meanwhile, detailed influence to EC's activity by these electrolytes have not been assessed experimentally to date.…”

Section: Introductionmentioning

confidence: 99%

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Endothelium Cell Responses on Pulsed-Anodized NiTi Alloy with HNO3, NH4NO3, H2SO4, and (NH4)2SO4 as Electrolytes

et al. 2023

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Pulsed anodization allows to form a Ni-free TiO 2 layer on an almost equiatomic NiTi alloy. The surface is then hydrophilized and impedes the release of Ni ions from the alloy. This study aimed to assess the suitability of electrolytes used in the pulsed anodization process with the view of application as a biomaterial. Toward this end, the NiTi alloy was pulsed-anodized in four different aqueous electrolytes, HNO 3 , NH 4 NO 3 , H 2 SO 4 , and (NH 4 ) 2 SO 4 , after which the endothelium cell behavior was compared. The use of H 2 SO 4 as the electrolyte resulted in the formation of a TiO 2 layer with a groove-like structure of several tens of nanometers wide, and this surface inhibited the activity of endothelium cells. The ability to prevent the release of Ni ions was diminished when using the HNO 3 electrolyte, resulted in inferior cell proliferation. The other two electrolytes, NH 4 NO 3 and (NH 4 ) 2 SO 4 , formed a Ni-free TiO 2 layer with a comparatively smooth surface, which more effectively suppressed the release of Ni ions; thus, the cell attachment as well as proliferation were superior to that of the other two electrolytes. The surface smoothness and Ni suppression were thus concluded to be the factors governing the selection of an electrolyte.

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Section: Characteristics Of the Pulsed-anodized Niti Surfacesmentioning

confidence: 77%

Section: Characteristics Of the Pulsed-anodized Niti Surfacesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Endothelium Cell Responses on Pulsed-Anodized NiTi Alloy with HNO3, NH4NO3, H2SO4, and (NH4)2SO4 as Electrolytes

et al. 2023

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“…Pulsed anodization of an almost equiatomic NiTi alloy with superelasticity is a novel surface modification process that enables the formation of an almost Ni-free oxide layer without raising the temperature of the alloy. 1,2 The process involves simple steps that connect a NiTi substrate to the anode in an electrolyte, then applying a rectangular pulse voltage with its lower value at zero volt. The thickness of the resultant layer is in the range of several tens of nanometers; thus, peeling off of the layer during superelastic deformation can be avoided.…”

Section: Introductionmentioning

confidence: 99%

Characteristic variation of pulsed‐anodized NiTi surface by the adjustment of voltage‐unapplied state

Taniho

Tate

Kawakami

et al. 2022

Surface & Interface Analysis

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Pulsed anodization of superelastic NiTi alloy in nitric acid electrolyte is a novel surface modification process that enables the formation of an almost Ni-free TiO 2 layer on their surface. The core technology is the modulation of voltage-unapplied state that is necessary for the chemical reaction with an electrolyte. Here, the effect of the adjustment of the voltage-unapplied state on the layer characteristics was investigated. Prolongation of the voltage-unapplied state led to the formation of a thicker

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“…NiTi alloys have been widely used in medical fields, [1][2][3] including the production of orthopedic and dental medical equipment, [4,5] owing to their unique properties of super elasticity, wear resistance, and biocompatibility. [6][7][8] However, the release of Ni ions from NiTi alloys can lead to adverse reactions in the human body. [9][10][11] Studying the corrosion resistance mechanism of NiTi alloys to prevent the precipitation of Ni ions has great practical significance.…”

Section: Introductionmentioning

confidence: 99%

Corrosion characterization of NiTi alloy by femtosecond laser surface processing

Yang

Wang

Bian

et al. 2022

Materials & Corrosion

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The study of the corrosion resistance of NiTi alloy surfaces with different wettabilities is important to achieve improvements in biocompatibility. In this study, a femtosecond laser was used to process different wettability surfaces on the NiTi alloy. The corrosion resistance of the surfaces was examined via potentiodynamic polarization and electrochemical impedance spectroscopy. Scanning electron microscopy and X‐ray photoelectron spectroscopy were used to analyze the morphology and chemical composition of the surfaces. The findings demonstrate that when an original oxide film is destroyed by femtosecond laser processing with a low laser fluence, hydrophilic or hydrophobic surfaces are more vulnerable to erosion. The corrosion resistance of superhydrophilic surfaces is improved to a certain extent, whereas superhydrophobic surfaces exhibit excellent corrosion resistance. Superhydrophilic surfaces are protected from further corrosion by the formation of a dense oxide film after corrosion, whereas superhydrophobic surfaces can inhibit corrosion because of their thicker oxide film and additional air film produced by air trapped in the micro/nanostructure.

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Electrolyte effect in pulsed anodization of NiTi alloy to form a Ni-free oxide layer

Cited by 9 publications

References 34 publications

Endothelium Cell Responses on Pulsed-Anodized NiTi Alloy with HNO<sub>3</sub>, NH<sub>4</sub>NO<sub>3</sub>, H<sub>2</sub>SO<sub>4</sub>, and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> as Electrolytes

Endothelium Cell Responses on Pulsed-Anodized NiTi Alloy with HNO<sub>3</sub>, NH<sub>4</sub>NO<sub>3</sub>, H<sub>2</sub>SO<sub>4</sub>, and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> as Electrolytes

Characteristic variation of pulsed‐anodized NiTi surface by the adjustment of voltage‐unapplied state

Corrosion characterization of NiTi alloy by femtosecond laser surface processing

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