Effects of Fine Particle Peening on Oxidation Behavior of Nickel–Titanium Shape Memory Alloy

Abstract

The effects of fine particle peening (FPP) on oxidation behavior of nickeltitanium shape memory alloy (NiTi alloy) were evaluated. After FPP treatment, oxidation process was performed at 300, 400 and 500°C for 30 min in N 2 20 vol%O 2 atmosphere. Surface microstructures of oxidized specimens pre-treated with FPP were characterized using scanning electron microscope (SEM), glow discharge optical emission spectroscopy (GD-OES), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction analysis (XRD). Oxide layers formed on the specimens pre-treated with FPP were thinner than those on the un-peened ones. Amorphous titanium oxides (TiO and TiO 2 ) were formed on the un-peened specimens by oxidation process, whereas a nickel oxide (NiO) was created on the FPP-treated surface oxidized at temperature greater than 400°C as well as titanium oxides. This was because an amorphous structure created by FPP accelerated the outward growth of nickel oxide during the subsequent oxidation process. Moreover, the effects of surface oxide layers on the biocompatibility of NiTi alloy were investigated. Due to the formation of a thin oxide layer which contains nickel element, the oxidized specimen pre-treated with FPP showed higher amount of nickel ion elution than that of the oxidized one during the cell culture tests. These results suggest that microstructural feature of surface oxide layer strongly affects the biocompatibility of NiTi alloy.

Enzyme‐free cell detachment mediated by resonance vibration with temperature modulation

“…The details of the design can be found in Kurashina et al (2017a). Note that the culture base was made of stainless steel with the surface modified using Fine Particle Peening (Kikuchi et al, 2014;Kurashina et al, 2014a). The diameter and the depth of the culture chamber were 40 mm and 10 mm, respectively.…”

Effective cell collection method using collagenase and ultrasonic vibration

“…2. Although metal cultivation surfaces are rarely used in tissue engineering researches, we previously proved that the metal surface modified with Fine Particle Peening (FPP) treatment is comparable to conventional plastic cell cultivation surface 19,20 and is therefore suitable for non-disposable cultivation equipment.…”