The effect of heating rate on the surface chemistry of NiTi

Undisz, Andreas; Hanke, Robert; Freiberg, Katharina; Hoffmann, Volker; Rettenmayr, Markus

doi:10.1016/j.actbio.2014.07.018

Cited by 16 publications

(6 citation statements)

References 26 publications

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“…[15][16][17] This hypothesis has been further investigated by studying heating rates and correlating the thermal profile to the type of oxide formed on the material. 18 These studies often seek answers to the following common questions: are certain surface finishes better than others and are oxides formed a certain way better than others? Previously issued FDA guidance for Intravascular Stents and Associated Delivery Systems 19 suggests oxide surfaces less than 50 nm thick and having acceptable corrosion resistance (as measured by ASTM F2129) do not need to perform Ni ion release testing.…”

Section: Introductionmentioning

confidence: 99%

“…Some authors have attributed the variable corrosion resistance of nitinol samples to the nature of the surface oxide layer(s) formed as a function of temperature and energetics of diffusion 15‐17 . This hypothesis has been further investigated by studying heating rates and correlating the thermal profile to the type of oxide formed on the material 18 . These studies often seek answers to the following common questions: are certain surface finishes better than others and are oxides formed a certain way better than others?…”

Section: Introductionmentioning

confidence: 99%

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The role of surface oxide thickness and structure on the corrosion and nickel elution behavior of nitinol biomedical implants

2021

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Biocompatibility is an important factor for metallic medical device implants, and corrosion resistance of implantable alloys is one aspect of biocompatibility. Corrosion behavior of nitinol is strongly dependent upon the nature of the surface oxide, which forms during processing. The surface oxide is comprised of a mixture of titanium and nickel oxides, and subsequent thermal exposure (e.g., during shape setting) and surface removal (e.g., electropolishing, mechanical polishing, etching, etc.) influence its structure. Corrosion behavior is often assessed through testing methods such as cyclic potentiodynamic polarization (e.g., ASTM F2129) and nickel ion release. Studies have suggested that a correlation exists between oxide thickness and nickel ion release, with thicker oxides eluting more nickel. It is hypothesized that the composition of the surface oxide, and not only its thickness, influences the corrosion performance of nitinol. To investigate this, nitinol wire samples were processed to produce surface oxides with different structures both in terms of thickness and composition. These samples were tested per ASTM F2129 and nickel ion release testing.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of surface oxide thickness and structure on the corrosion and nickel elution behavior of nitinol biomedical implants

2021

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“…In this geometry, the probed area was about 6 × 7 mm 2 (illumination width limited by a lead foil) adapted to the lateral dimension of the laser-processed region. Quantitative depth profiles of Ti, Al, V, O, and C were determined by GD-OES (SPECTRUMA Analytik GmbH, GDA 750) using the GD-OES method as presented in [34]. Re-calibration and modification of the method were carried out using well-defined reference specimens to account for the additional elements Al and V. The measurements were performed in radio frequency mode in order to allow for plasma ignition when working with samples covered by a non-conducting surface layer.…”

Section: Surface Characterizationmentioning

confidence: 99%

“…The conversion of the measured intensities to quantitative concentrations for each element depends on numerous factors including sputtering rate factors or specific emission characteristics. Thus, the conversion of measured intensities to quantitative concentrations requires a calibration method as described in [34], and the progression of quantitative concentration profiles may differ significantly from the progression of the intensity profiles. As an example, in Fig.…”

Section: Gd-oes Characterization Of Lsfl Grooves and Spikesmentioning

confidence: 99%

“…Similar to XPS or AES, measurement and conversion of the acquired data to quantitative concentration versus depth profiles may be affected, e.g., by pronounced surface topography of the samples, different sputtering yield of the elements involved, or a non-planar ground of the sputtering crater as a result of plasma conditions. The depth resolution attained by GD-OES was estimated to be ~ 15% of the actual sputtering depth, applying the specific method to equiatomic NiTi alloys [34]. Additionally, ignition and stabilization of the plasma at the beginning of each measurement require several milliseconds, corresponding to a few nanometers of the sample surface being removed before meaningful results can be attained.…”

Section: Introductionmentioning

confidence: 99%

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Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy

et al. 2020

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In this contribution, chemical, structural, and mechanical alterations in various types of femtosecond laser-generated surface structures, i.e., laser-induced periodic surface structures (LIPSS, ripples), Grooves, and Spikes on titanium alloy, are characterized by various surface analytical techniques, including X-ray diffraction and glow-discharge optical emission spectroscopy. The formation of oxide layers of the different laser-based structures inherently influences the friction and wear performance as demonstrated in oil-lubricated reciprocating sliding tribological tests (RSTTs) along with subsequent elemental mapping by energy-dispersive X-ray analysis. It is revealed that the fs-laser scan processing (790 nm, 30 fs, 1 kHz) of near-wavelength-sized LIPSS leads to the formation of a graded oxide layer extending a few hundreds of nanometers into depth, consisting mainly of amorphous oxides. Other superficial fs-laser-generated structures such as periodic Grooves and irregular Spikes produced at higher fluences and effective number of pulses per unit area present even thicker graded oxide layers that are also suitable for friction reduction and wear resistance. Ultimately, these femtosecond laser-induced nanostructured surface layers efficiently prevent a direct metal-to-metal contact in the RSTT and may act as an anchor layer for specific wear-reducing additives contained in the used engine oil.

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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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The effect of heating rate on the surface chemistry of NiTi

Cited by 16 publications

References 26 publications

The role of surface oxide thickness and structure on the corrosion and nickel elution behavior of nitinol biomedical implants

The role of surface oxide thickness and structure on the corrosion and nickel elution behavior of nitinol biomedical implants

Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy

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

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