Comparison of NiTi alloy surfaces formed by anodization in nitric, phosphoric, and sulfuric acid electrolytes

Ohtsu, Naofumi; Hirano, Yuma; Takiguchi, Koudai

doi:10.1016/j.surfcoat.2017.12.050

Cited by 12 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This reaction is further beneficial for the layer growth; for example, the oxidization reaction is induced by nitric acid, which acts as the electrolyte and eliminates Ni from the layer surface. [11][12][13][14] Ni, which exists in the metallic state in the oxide layer, impedes the growth of the anodic oxide layer, thus affecting the insulation performance of the layer. 15 Consequently, Ni elimination facilitates layer growth.…”

Section: Introductionmentioning

confidence: 99%

Characteristic variations in a pulsed‐anodized NiTi alloy surface by the lower voltage setting

Kawakami,

Matsui,

Tsuruta

et al. 2024

Surface & Interface Analysis

Self Cite

View full text Add to dashboard Cite

Pulsed anodization of a nearly equiatomic NiTi alloy in HNO3 leads to the formation of a nearly Ni‐free oxide layer, resulting in the suppression of Ni‐ion release from the alloy surface. The core technology involves introduction of a lower‐voltage period, which promostes chemical reactions between the alloy and electrolyte, to obtain a surface layer with better corrosion protection. In this study, a higher voltage of 3.5 V was applied, and the lower voltage was varied within 0–3.5 V. As the lower voltage was increased, nanometer‐sized pores present on the anodized surface gradually expanded, while the layer thickness decreased. Although the corrosion protectivity of the layer did not change significantly during the electrochemical experiments, the amount of Ni‐ion released into the physiological solution significantly decreased when the voltage was below 1.8 V. X‐ray photoelectron spectroscopy analyses revealed the presence of Ni (OH)2 on the topmost surface, and its concentration decreased at a voltage <1.8 V. Lower voltages affected the concentration of Ni (OH)2 on the topmost surface and thus considerably influenced the Ni‐ion release behavior. These findings will contribute to the production of NiTi alloys with improved biocompatibility.

show abstract

Section: Introductionmentioning

confidence: 99%

Characteristic variations in a pulsed‐anodized NiTi alloy surface by the lower voltage setting

Kawakami,

Matsui,

Tsuruta

et al. 2024

Surface & Interface Analysis

Self Cite

View full text Add to dashboard Cite

show abstract

“…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

Self Cite

View full text Add to dashboard Cite

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

show abstract

“…Therefore, surface modification techniques such as anodization, electrodeposition, and heat treatments have generally been applied in order to increase the crystallinity of oxide films and improve their surface properties 5 . Anodization is an important electrochemical surface modification technique, which consists in growing an oxide film with high adhesion to the substrate which is able to promote an increase in thickness and crystallinity of the passive film 2,6,7 .…”

Section: Introductionmentioning

confidence: 99%

Morphological and Structural Variations in Anodic Films grown on Polished and Electropolished Titanium Substrates

et al. 2019

View full text Add to dashboard Cite

Comparison of NiTi alloy surfaces formed by anodization in nitric, phosphoric, and sulfuric acid electrolytes

Cited by 12 publications

References 29 publications

Characteristic variations in a pulsed‐anodized NiTi alloy surface by the lower voltage setting

Characteristic variations in a pulsed‐anodized NiTi alloy surface by the lower voltage setting

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

Morphological and Structural Variations in Anodic Films grown on Polished and Electropolished Titanium Substrates

Contact Info

Product

Resources

About