Sonntag Robert, Feige Katja, Dos Santos Claudia Beatriz, Kretzer Jan Philippe
Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, 69118 Heidelberg, Germany.
Fraunhofer Institute for Manufacturing Engineering and Automation IPA, Department Electroplating, 70569 Stuttgart, Germany.
Materials (Basel). 2017 Dec 20;10(12):1449. doi: 10.3390/ma10121449.
Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr) electrolyte with a reduced chromium trioxide (CrO₃) content, both without solid additives and (c) with the addition of fullerene (C) nanoparticles; and (d) a trivalent chromium (Cr) electrolyte with C addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23-40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70-84% compared with the CoCr-CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect.
金属对金属全髋关节置换轴承已被引入，作为年轻且活动较多患者中聚乙烯的替代方案。然而，这些轴承已被证明易于植入位置不当，并受到一些特定设计特征的限制。在这种情况下，涂层提供了一种通过保持金属基材的高断裂强度来提高耐磨性的选择。设计了一种定制的电镀装置，用于在钴铬基材上涂覆涂层，使用：(a) 工业标准铬电解液；(b) 一种定制的六价铬（Cr）电解液，其中三氧化铬（CrO₃）含量降低，两者均无固体添加剂，以及 (c) 添加富勒烯（C）纳米颗粒；和 (d) 添加 C 的三价铬（Cr）电解液。与金属基材相比，所有涂层的显微硬度均有所增加。三价涂层比六价涂层（23 - 40 µm）更薄（10 µm），并导致粗糙度和裂纹密度增加。与钴铬 - 钴铬参考轴承相比，发现六价铬涂层的磨损减少了 70 - 84%，而三价铬涂层甚至使磨损增加了 300% 以上。向电解液中添加富勒烯未显示出任何进一步的摩擦学效应。
