Development of titanium wire ropes for implantable stimulation electrode and their evaluation.

利用医用生物材料研究了磨屑形成、离子洗脱、气体表面硬化、细胞与钛粉的反应等磨损特性及相关问题。(1)植入材料在模拟体液中的磨损特性。在钛材料销盘磨损试验中，离子在1质量%乳酸溶液中的淋洗作用比在Hanks‘s溶液中的离子淋洗作用更明显。由质量损失计算的磨损量随滑动距离或接触压力变化不大，而金属离子的洗脱率随滑动距离的增大而增大。用CP钛销钉和圆盘进行磨损试验，磨损量均大于α+β钛合金。结果表明，Cp钛销钉与磁盘的界面处发生了粘着磨损。当使用PSZ或Si_3N_4销钉和CP钛圆盘时，磨损量比使用其他陶瓷销钉低，洗脱率高。(2)表面硬化对钛的磨损性能的影响。对CP钛或β-14Mo-3Nb-1.5Zr合金进行销盘磨损试验时，采用CO气体进行表面硬化处理，可以减少质量损失。由于氧或碳在β结构钛合金中的溶解度远高于α结构钛合金中的氧和碳的溶解度，因此CO气体对CP钛合金的表面强化效果优于β钛合金。结果：1.钛粉在模拟体液中引起离子洗脱，但在磨损试验中离子洗脱占总离子洗脱的比例相对较低。钛离子对Raw264细胞活力有一定的抑制作用，且钛离子影响细胞内超氧化物歧化酶活性和肿瘤坏死因子-α的形成。观察到RAW264细胞吞噬了直径为10μm的钛粉，表明细胞与钛粉之间存在积极的相互作用。

Wear property and related issues such as wear debris formation, ion elution, surface hardening using gas, reaction between cell and titanium powder were investigated using biomaterials for medical applications.(1) Wear properties of implant materials in simulated body fluids1. Ion elution into 1 mass% lactic acid solution during pin-on-disk wear test of titanium materials was more significant than that into Hanks' solution.2. Wear loss calculated from mass loss was almost constant with sliding distance or contact pressure for biomaterials examined, while elution rate of metal ions increased with increasing sliding distance.3. When CP titanium pin and disk were used for wear test, the wear loss was higher than that of α+β titanium alloys. It was suggested that adhesive wear occurred at the interface between CP Ti pin and disk.4. When PSZ or Si_3N_4 pin and CP Ti disk were used, wear loss was lower than that using other ceramic pin, and elution rate was higher.(2) Effect of the surface hardening on wear property of titanium1. Mass loss during pin-on-disk wear test for CP titanium or β-type Ti-14Mo-3Nb-1.5Zr alloy was decreased by surface hardening using CO gas.2. The surface hardening using CO gas for CP titanium was more effective than that for β-type Ti-14Mo-3Nb-1.5Zr alloy, because solubility of oxygen or carbon in CP titanium with α type structure was much higher than in β-type titanium alloys.(3) In vivo and in vitro evaluation of wear debris1. Titanium powder caused the ion elution in simulated body fluids, but the ion elution is relatively low in total ion elution during wear test.2. RAW 264 cell viability was decreased by titanium ion, and the titanium ion affected the SOD activity and TNF-α formation.3. It was observed that RAw264 cells phagocytosed titanium powder with 10 μm in diameter, which suggested the active interaction between the cell and titanium powder.