Total hip replacement is the most effective treatment for late stage osteoarthritis. However, adverse local tissue reactions (ALTRs) have been observed in patients with modular total hip implants. Although the detailed mechanisms of ALTRs are still unknown, fretting corrosion and the associated metal ion release from the CoCrMo femoral head at the modular junction has been reported to be a major factor. The purpose of this study is to increase the fretting corrosion resistance of the CoCrMo alloy and the associated metal ion release by applying hard coatings to the surface. Cathodic arc evaporation technique (arc-PVD) was used to deposit TiSiN and ZrN hard coatings on to CoCrMo substrates. The morphology, chemical composition, crystal structures and residual stress of the coatings were characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, and X-ray diffractometry. Hardness, elastic modulus, and adhesion of the coatings were measured by nano-indentation, nano-scratch test, and the Rockwell C test. Fretting corrosion resistance tests of coated and uncoated CoCrMo discs against Ti6Al4V spheres were conducted on a four-station fretting testing machine in simulated body fluid at 1Hz for 1 million cycles. Post-fretting samples were analyzed for morphological changes, volume loss and metal ion release. Our analyses showed better surface finish and lower residual stress for ZrN coating, but higher hardness and better scratch resistance for TiSiN coating. Fretting results demonstrated substantial improvement in fretting corrosion resistance of CoCrMo with both coatings. ZrN and TiSiN decreased fretting volume loss by more than 10 times and 1000 times, respectively. Both coatings showed close to 90% decrease of Co ion release during fretting corrosion tests. Our results suggest that hard coating deposition on CoCrMo alloy can significantly improve its fretting corrosion resistance and could thus potentially alleviate ALTRs in metal hip implants.

全髋关节置换是晚期骨关节炎最有效的治疗方法。然而，在模块化全髋关节植入物患者中已经观察到不利的局部组织反应（ALTR）。尽管还不清楚ALTR的详细机理，但据报道，微动腐蚀以及在模块化连接处从CoCrMo股骨头中释放出的相关金属离子是主要因素。这项研究的目的是通过在表面涂覆硬涂层来提高CoCrMo合金的耐微动腐蚀性能以及相关的金属离子释放。阴极电弧蒸发技术（arc-PVD）用于将TiSiN和ZrN硬涂层沉积到CoCrMo基板上。用扫描电镜对涂层的形貌，化学组成，晶体结构和残余应力进行了表征，能量色散X射线光谱法和X射线衍射法。涂层的硬度，弹性模量和附着力通过纳米压痕，纳米划痕测试和洛氏C测试进行测量。在四工位微动试验机上，在1Hz的模拟体液中，对经涂覆和未涂覆的CoCrMo圆盘对Ti6Al4V球的抗微动腐蚀性能进行了100万次循环。分析微滴后样品的形态变化，体积损失和金属离子释放。我们的分析表明ZrN涂层具有更好的表面光洁度和较低的残余应力，而TiSiN涂层具有更高的硬度和更好的耐划伤性。微动结果表明，两种涂层的CoCrMo的微动耐腐蚀性均得到了显着改善。ZrN和TiSiN减少了微动量损失超过10倍和1000倍，分别。在微动腐蚀试验中，两种涂层均显示出Co离子释放量减少了近90％。我们的结果表明，在CoCrMo合金上进行硬涂层沉积可以显着提高其抗微动腐蚀性能，因此可以缓解金属髋关节植入物中的ALTR。