Papers by Author: C.L. Chu

Abstract: Electro-Fenton process as a modified Fenton’s oxidation method in waster water treatment can provide a stable hydroxyl radical (·OH) source by continuous reaction of electrochemically generated H2O2 with Fe2+ ions for surface oxidation modification of NiTi shape memory alloy (SMA). In this work, effects of electro-Fenton process on blood compatibility and nickel suppression of NiTi SMA were investigated by SEM and XPS, inductively-coupled plasma mass spectrometry (ICPMS), hemolysis analysis and blood platelet adhesion test. It is found that electro-Fenton process is a notably effective way to impede out-diffusion of Ni from NiTi SMA in simulated body fluids during the entire ten week immersion period. It can also improve the hemolysis resistance and thromboresistance of biomedical NiTi SMA. The improvement of blood compatibility and nickel suppression of NiTi SMA can be attributed to the formation of surface titania film with a Ni-free zone near its top surface by electro-Fenton process.

Abstract: A graded titania film was formed on chemically polished NiTi shape memory alloy (SMA) by a novel deposition-assisted advanced oxidation method in a modified Fenton’s reagent containing titanium tetrachloride and then characterized by SEM and XPS. The effects of the titania film on leaching of harmful Ni ions from the NiTi substrate in simulated body fluids (SBF) is assessed by inductively-coupled plasma mass spectrometry (ICPMS). The results indicate that a thick and dense titania film was successfully fabricated in this in situ advanced oxidation reaction assisted with an additional deposition process by the hydrolysis of titanium tetrachloride on NiTi. The titania film can dramatically reduces Ni leaching from NiTi. XPS depth profiles show that the film possesses a smooth graded interfacial structure that boost mechanical stability.