Effects of H 2O 2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

Abstract

The effects of H 2O 2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA) were investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF) soaking test. It is found that the H 2O 2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni 2O 3, Na 2TiO 3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment. As a result, the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na + ions from Na 2TiO 3 phase with H 3O + ions in SBF, which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H 2O 2 pretreatment.