Growth of oxide layers on NiTi alloy surfaces through anodization in nitric acid electrolyte

Ohtsu, Naofumi; Hirano, Yuma

doi:10.1016/j.surfcoat.2017.06.021

Cited by 22 publications

(8 citation statements)

References 29 publications

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“…This indicates the applicability limit of this thin‐film optical interference approach. Even though the minimum value of titanium oxide thickness that can be determined is around 75 nm in this study, the interference colors of yellowish‐gold and blue can still be observed from the oxidized NiTi alloy with oxide thickness between 20 nm and 50 nm [12, 36, 37].…”

Section: Discussionmentioning

confidence: 64%

Estimation of titanium oxide layer thickness on thermally oxidized NiTi alloy based on color variations

Mahmud

Ahmad

et al. 2022

Materialwissenschaft Werkst

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This paper studies the estimation of titanium oxide (TiO2) thickness on a thermally oxidized nickel titanium (NiTi) alloy based on its surface color. The NiTi plate specimens were subjected to oxidation at temperatures from 450 °C to 900 °C for different duration to induce the formation of oxide layers of different thicknesses. The oxide thickness of the specimens oxidized from 650 °C to 900 °C was measured by means of scanning electron microscopy. A fitting curve was generated from the measured thicknesses, and further extrapolated to predict the oxide thickness for specimens heated at lower temperature of 450 °C to 600 °C. The oxide thickness estimation was done using thin‐film optical interference, with reference to the observed color of the oxidized surface. The thin‐film optical interference approach showed accurate measurement of oxide thickness as compared to the extrapolated data, highlighting the applicability of this measurement technique.

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Section: Discussionmentioning

confidence: 64%

Estimation of titanium oxide layer thickness on thermally oxidized NiTi alloy based on color variations

Mahmud

Ahmad

et al. 2022

Materialwissenschaft Werkst

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“…Using the pulsed voltage accords with the insertion of “voltage‐unapplied state.” In the voltage‐unapplied state, the anodic reaction is suspended, but the chemical reaction from the electrolyte proceeds continuously. Thus, selecting an adequate electrolyte that hinders the negative effect of Ni in the alloy can lead to the growth of the anodized layer 18–21 . For instance, selecting a strong oxidative agent, such as a nitrate electrolyte, selectively eliminates the obstructive Ni, thereby facilitating the growth of an anodized layer.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, selecting an adequate electrolyte that hinders the negative effect of Ni in the alloy can lead to the growth of the anodized layer. [18][19][20][21] For instance, selecting a strong oxidative agent, such as a nitrate electrolyte, selectively eliminates the obstructive Ni, thereby facilitating the growth of an anodized layer. The resultant anodized layer is an almost Ni-free TiO 2 layer of $50 nm thickness and is homogeneous, owing to which the surface is hydrophilic and improves its corrosion resistance.…”

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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“…However, most of the techniques only enhanced the native formation or passivation of the oxide film via oxidation treatment. These techniques include autoclaving and boiling baths [13], selective oxidation [14], sol-gel technology [15], and anodization in acid electrolytes [16], among other methods. In these studies, the nickel ion migration was minimized; however, the formed oxide layers were excessively thin and unable to withstand sufficiently long implantation periods.…”

Section: Introductionmentioning

confidence: 99%

Parametric evaluation of electrical discharge coatings on nickel-titanium shape memory alloy in deionized water

Mansor

Azmi

Zain

et al. 2020

Heliyon

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Nickel-titanium shape memory alloy (NiTi) has a unique capacity to restore its initial shape after deformation, which is highly applicable to orthopaedic implantations, especially for the minimization of invasive surgeries. The high nickel content of this alloy can lead to unfavourable effects on the human body upon dissolution; thus, a reliable barrier of coatings on the NiTi surface is required to alleviate the nickel migration and increase its biocompatibility. In this paper, analyses of a titanium oxide layer development on NiTi surface using electrical discharge coating (EDC) process is presented. The recast layer thickness, crater sizes, and surface roughness were characterized based on five parameters; polarity, discharge duration, pulse interval, peak current, and gap voltage. The results show that the discharge duration is the most significant parameter to influence all responses, followed by peak current. The surface characteristics of the EDC substrate is depending on the crater formations and is highly correlated with the discharge energy intensity. As a result, appropriate parametric conditions of the electrical discharge coating process can enhance the NiTi surface for future medical applications, without compromising the shape memory effect.

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Growth of oxide layers on NiTi alloy surfaces through anodization in nitric acid electrolyte

Cited by 22 publications

References 29 publications

Estimation of titanium oxide layer thickness on thermally oxidized NiTi alloy based on color variations

Estimation of titanium oxide layer thickness on thermally oxidized NiTi alloy based on color variations

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

Parametric evaluation of electrical discharge coatings on nickel-titanium shape memory alloy in deionized water

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