SURFACE TREATMENT OF SHAPE MEMORY ALLOY APPLING TO SURGERY MATERIALS AND ITS EVALUATION

作者的目的是应用镍钛形状记忆合金作为植入材料。然而，它经历点蚀。因此，采用等离子喷涂的方法在Ni-Ti合金表面镀上Ti，但多孔的Ti层加速了基体的点蚀。尝试用生物相容性高分子树脂对喷镀钛层的孔隙进行密封。在本系列研究中，采用自固化型有机硅树脂、双液型环氧树脂和即固化型氰基丙烯酸树脂三种高分子树脂作为密封胶。评价和讨论了它们对孔隙密封和点蚀防护的作用。所采用的商用硅树脂胶粘剂和环氧树脂胶粘剂的黏度都很高，无法穿透多孔钛层。需要用溶剂稀释粘合剂。有机硅树脂的最佳溶剂是四氯化碳，环氧树脂的最佳溶剂是丙酮。此外，超声波对稀释树脂胶粘剂的渗透效果也很好。这似乎是因为毛孔中的空气很容易被清除。氰基丙烯酸树脂胶粘剂粘度小，可以认为不需要稀释。然而，即使氰基丙烯酸酯很容易渗透，它在到达钛层底部之前很快就凝固了。因此，需要稀释来控制凝固。电化学极化实验评价结果表明，各树脂到达钛层底部的最佳条件为环氧树脂>氰基丙烯酸树脂>有机硅树脂。保护能力的差异似乎源于水分子的可吸收性的差异。等离子体镀四氟乙烷树脂是合金镀层的另一种方法，但不适合实际应用。

The authors aim to apply Ni-Ti shape memory alloy as an implant material. However, it undergoes pitting corrosion. Thus, the surface of Ni-Ti alloy was coated with Ti by plasma spray, but as a result, the porous ti layr accelerates pitting corrosion of the substrate. The pores of the sprayd Ti layr was made attempt to be sealed with biocompatible polymer resins. In a series of this research, three polymer resins of self-solidified type silicone resin, two-liquid type epoxy resin and instantly-solidified type cyanoacryl resin were employed as a sealant. Their effect on sealing of pores and protection of pitting corrosion was evaluated and discussed. Both the commercial silicone resin adhesive and epoxy resin adhesive employed were so highly viscous that cannot penetrate into porous Ti layr as they are. Dilution of the adhesives by solvents were required. Carbon tetrachloride was the best solvent for silicone resin but acetone was the best for epoxy resin. Moreover, Supersonic wave gave a good effect on penetration of diluted resin adhesives. This seems to be because the air in the pores is easily removed. Cyanoacryl resin adheseiv is so less viscous that it can be considered that it does not need dilution. However, even if cyanoacrylate easily penetrates, it soon solidifies before reaching the bottom of the Ti layr. Therefore, dilution is required to control solidification. From the results of evaluation by electrochemicla polarization experiment, an optimum condition was obtained to reach the bottom of Ti layr for each resins but comparing each other protection abbility to pitting corrosion was ranked as epoxy resin>cyanoacryl resin>silicone resin. Difference in the protection ability seems to be stemed from that in absorbability of water molecules. As another technique for coating trhe alloy, plasma-plating of tetrafluoroethane resin was tried but it could not stand practical usage.