Influence of Milling–Electrochemical Polishing on Corrosion Resistance of NiTi Shape Memory Alloy

Abstract

As an important artificial implant material, the corrosion resistance of NiTi shape memory alloy is closely related to the machined surface quality. In this paper, the multiple analysis methods concerning potentiodynamic polarization, impedance spectrum and corrosion morphology are used to analyze the corrosion resistance of the alloy. The potentiodynamic polarization and impedance spectrum test results show that the conductivity and corrosion current density of electrochemical polishing surface decrease, and the polarization resistance and corrosion potential increase compared with milling. After electrochemical polishing, the surface roughness of the milling sample is decreased, and the NiTi alloy of austenite phase is transformed into TiO2, which improves the corrosion resistance of the alloy. In addition, there are pitting corrosion, hole corrosion and crevice corrosion morphology on the milling surface, while the pitting corrosion and hole corrosion exist on the electrochemical polishing surface. The corrosion morphology verified the analysis of potentiodynamic polarization and impedance spectrum. The multiple analysis method proposed in this paper can be used as a more accurate evaluation method for the corrosion resistance of alloy surface, avoiding the error of analysis results caused by the impedance spectrum equivalent circuit and potentiodynamic polarization following Tafel relationship.

Preparation of a novel antibacterial magnesium carbonate coating on a titanium surface and its in vitro biocompatibility

“…68 Additionally, its cleaning and etching capabilities contributed to a smoother surface texture. 69–71 Compared to the untreated magnesium coating, the Ra and Rq values were lower. A similar observation was made on the titanium substrate surfaces (Ti vs. Ti–H 2 O 2 ), where the surface wettability of the coating were enhanced relative to the original Ti surface.…”

Influence of technological synthesis conditions on corrosion behaviour and mechanical properties for NiTi alloys

“…In turn, the passivation layer composed of TiO 2 has high stability. The greatest influence on the change of this stability has the condition of the alloy surface, because lower surface roughness can reduce the adsorption effect of Cl ions and, consequently, reduce the progress of pitting corrosion (Guijie et al , 2022). In this work, the NiTi MM’ed sample was characterized by a lower surface roughness before the immersion tests.…”

Analysis of Cutting Forces and Geometric Surface Structures in the Milling of NiTi Alloy

“…Materials with shape memory and superelasticity are considered new materials. These are original materials with significant potential for applications in modern mechanical structures, materials engineering, or medicine [1][2][3][4][5]. Referred to as multifunctional and intelligent, they are commonly produced as alloys based on nickel and titanium (NiTi), possessing the unique ability to regain their original shape after deformation.…”

“…Referred to as multifunctional and intelligent, they are commonly produced as alloys based on nickel and titanium (NiTi), possessing the unique ability to regain their original shape after deformation. The distinct characteristics of the NiTi alloy, coupled with additional advantages such as biocompatibility, high plasticity, a favorable strength-to-weight ratio, corrosion resistance even in aggressive environments, and favorable parameters in terms of mechanical strength, fatigue strength, and specific weight, have fueled a growing interest in materials derived from this alloy in the field of modern mechanical systems utilized in technology and medicine [2][3][4][5][6].…”