激光表面改性对NiTi形状记忆合金腐蚀行为的影响

Corrosion behavior of the nitrided of NiTi shape memory alloy in simulated body fluid solution

采用连续波Nd:YAG固体激光,在NiTi形状记忆合金表面制备出表面致密、无孔洞和裂纹的氮化层,测试了这种激光改性层在37℃模拟人体体液Hank's溶液中的电化学阳极极化曲线和交流阻抗谱,研究了改性层的腐蚀行为．结果表明,NiTi合金氮化层的腐蚀电位和击穿电位正移,反应转移电阻明显提高,而腐蚀电流及界面电容下降．这说明激光气体氮化有效地改善了NiTi形状记忆合金在模拟人体体液中的电化学抗腐蚀性能．

Laser gas nitrided （LGN） layer on the surface of NiTi shape memory alloy （SMA） was fabricated by irradiation of Nd-YAG laser in N2 environment. A compact laser modified coating reinforced with fine TiN metal matrix composite was obtained. The corrosion behavior of the laser gas nitrided layer in Hank＇s simulated body fluid at 37 ℃ was investigated. The corrosion potential, breakdown potential and polarization resistance of laser gas nitrided NiTi SMA are higher than those of NiTi SMA. The values of corrosion current and interfacial capacitance are lower. Laser surface modification effectively improved the corrosion resistance of NiTi SMA used as an implant biomedical material in simulated body fluid.