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采用电化学测试技术研究了在PBS人工模拟体液中纤维蛋白原对CoCrNiMo和CoCrNiW合金腐蚀行为的影响.结果表明,CoCrNi合金具有良好的耐孔蚀性能,其钝化电位区较宽,且电位扫描曲线滞后环面积小.用EDX能谱对试样进行分析发现,在CoCrNi合金表面形成了Co,Cr,Ni,Mo,W等的钝性金属氧化物膜.纤维蛋白原在CoCrNi合金表面发生了吸附,且吸附的蛋白质分布不连续.用紫外吸收法测量CoCrNiMo和CoCrNiW对纤维蛋白原的吸附量分别为10.628 μg/cm2和9.561μg/cm2.含有纤维蛋白原的PBS人工模拟体液中CoCrNi合金的腐蚀行为可用吸附理论解释.其反应步骤为:(1)氧原子吸附在合金能量较高的活性点上,形成较为稳定的吸附氧化膜;(2)纤维蛋白原扩散到合金表面以形成络合物的形式与氧原子构成竞争吸附;(3)形成的金属络合物向溶液产生电化学迁移,破坏了合金表面的钝性氧化膜,使icorr值显著增大,加剧了合金的腐蚀.

The effect of fibrinogen on the corrosion behavior of CoCrNiMo and CoCrNiW alloys in PBS simulated body fluid were studied with electrochemical method. The results show that CoCrNi alloys, with extensive passive potential region and small hysteresis loop, exhibited excellent resistance to pitting corrosion. According to the analysis of energy-dispersive X-ray(EDX), it was found that the passive oxide film composed of Co, Cr, Ni, Mo and W etc. was formed on the surface of the alloys. The distribution of the fibrinogen which was absorbed on the surface was not successive. At the same time, the amount of fibrinogen adsorption measured by UV ray absorption method was 10.628 μg/cm2 for CoCrNiMo alloy and 9.561 μg/cm2for CoCrNiW alloy. On the basis of the analysis and discussion, the corrosion behavior of CoCrNi alloys could be explained by adsorption theory. Its processes were as followed: (1) Oxygen atoms are adsorbed on the active region with high energy,and formed stable adsorbed oxide film. (2) The fibrinogen diffusing to the surface of alloys suffered competitive adsorption with oxygen atom. (3) The electrochemical transference occurred and the formed complex of metal and protein was brought into the solution, which destroyed the passive oxide film, enlarged icorr greatly and aggravated the corrosion of the alloy.