Surface analyses and biocompatibility study of 500 °C oxidized Ni50Ti50 and Ni40Ti50Cu10 shape memory alloys

✍ Scribed by Ming-Chuan Chen; Shyi-Kaan Wu

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 891 KB
• Volume: 203
• Category: Article
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2009.01.012

✦ Synopsis

D] Oxygen [D] Titanium alloy [X] Biocompatibility

Ni 50 Ti 50 and Ni 40 Ti 50 Cu 10 shape memory alloys (SMAs) are oxidized at 500 °C. Considering the surface roughness, the thicknesses of oxide layer and Ni-free layer, the surface Ni concentration, the proper oxidation times for oxidized specimens are found to be 60 min for Ni 50 Ti 50 and 30 min for Ni 40 Ti 50 Cu 10 . Experimental results reveal that the oxidation is diffusion-controlled with its oxide layer containing titanium oxide and that the surface Ni concentration is much lower than the nominal composition. When Ni 50 Ti 50 and Ni 40 Ti 50 Cu 10 SMAs are oxidized at these times, the latter has better corrosion resistance than the former in Hanks' solution at 27 °C. However, the results of cytotoxicity and cell proliferation assays indicate that the biocompatibility of unoxidized Ni 40 Ti 50 Cu 10 is worse than that of unoxidized Ni 50 Ti 50 , but that of oxidized Ni 40 Ti 50 Cu 10 ranks as good as that of oxidized Ni 50 Ti 50 .