低温去合金化脱镍处理镍钛记忆合金的表面特性

采用低温去合金化(Dealloying)处理法对医用NiTi合金进行表面脱镍改性。经SEM、XRD、AES、FTIR、XPS和模拟体液(SBF)仿生沉积等分析研究表明,NiTi合金经低温去合金化处理后,在合金表面选择性地除去了有害元素镍,在距表层约400nm深度内原位制备出完全无镍的具有纳米网架结构的水合氧化钛膜,并在500℃,进行1h热处理,晶化为锐钛矿型二氧化钛。由于经低温去合金化脱镍的NiTi合金表面富含羟基(OH-),在SBF溶液中具有良好的生物活性,从而提高了NiTi合金的生物相容性。

Surface Characteristics of NiTi Alloys Modified by Dealloying at Low Temperature

A dealloying treatment method was applied to the surface modification of nearly equiatomic NiTi alloy so as to remove the harmful element of nickel selectively from NiTi alloys and form a Ni-free titanium oxide layer on the surface. Sample surfaces were analyzed by SEM, XRD, AES, FTIR and XPS, and then samples were immersed in SBF solution for 14 d in order to observe the bioactivity. The results show that the dealloying treatment of NiTi alloy at low temperature leads to 400 nm thick Ni-free surface layer that possesses a nanometer grid structure, and titania surface is in situ formed that possesses a degree of bioactivity because of the combination of hydroxyl (OH-) group in the process of dealloying treatment simultaneously. As-prepared titania layer was changed into anatase after heated at 500 oC for 1 h. As a consequence, the dealloying treatment method could improve biocompatibility of NiTi alloys.