等离子表面改质技术提高人工关节抗磨损效能的实验研究

An experimental study on the plasma surface modification technique for the improvement of wear resistance of an artificial joint

目的利用等离子浸没注入技术（PIII）改质钛-铝-钒（Ti-6Al—4V）表面，探讨高温注入及后续退火处理的改性效果。方法将Ti-6Al—4V合金以氮气等离子注入，藉检测表面氮离子的分布、表面结构／粗糙度、材料晶体及摩擦系数等性质，以评估PIII表面改性的效果。结果提高注入温度，表面氮注入层浓度的峰值呈轻度下降；渗透深度则略为上升。硬度与注入层厚度呈良好相关性，但在高温下注入，表面溅射将造成材料的粗化，摩擦系数上升。600—800℃间高温下退火处理，同样可达到提高注入深度及促使TiN及Ti2N晶体生成、提升硬度的效果，同时升温退火处理也会造成粗糙度的微幅上升。结论本研究藉表面物化性及力学性质的量测，初步发现Ti-6Al—4V于室温下以等离子浸没注入技术注入，并于700℃下经30min退火处理，可得到高硬度、低摩擦系数、耐磨损的适用于人工关节应用表面的技术。

Objective The effects of implantation and annealing temperatures on the surface properties of a Ti-6Al- 4V alloy modified by the plasma ion immersion implantation （PIII） technique. The results are to be applied to the development of a surface plasma treatment technique for the metallic element used in an artificial joint. Methods The substrates of Ti-6Al-4V alloy were implanted by N2 plasma and surface properties of： nitrogen distribution profile, surface morphology/roughness, crystallographic structure, and friction coefficient were analyzed to evaluate the performance of the modified surfaces. Results Increasing the implantation temperature in a PIII process slightly decreases the peak concentration of the implanted nitrogen layer while increases the penetration depth. As the temperature rises, the plasma ions strike a surface with higher energy and thus induce surface sputting, which increases surface roughness and friction coefficient. Surfaces annealed at 600 -800℃ is accompanied with the increases in nitrogen penetration depth, TiN and Ti2N formation, and surface hardness. Also, the surface roughness is slightly increased with the annealing treatment. Conclusions By analyzing the chemical, physical and mechanical properties of a surface modified by plasma ion immersion implantation technique, it is found that a Ti-6Al-4V surface implanted at room temperature followed by annealing at 700℃ for 30 min gives high surface hardness and the lowest friction coefficient and appeared to be the most promising technique for improving the wear resistance of a Ti-6Al-4V alloy material.