Cassar Josianne, Mallia Bertram, Karl Andreas, Buhagiar Joseph
Department of Metallurgy and Materials Engineering, University of Malta, Msida, MSD2080, Malta.
Bodycote Specialist Technologies GmbH, Landsberg, Germany.
Mater Sci Eng C Mater Biol Appl. 2017 Jun 1;75:1366-1375. doi: 10.1016/j.msec.2017.03.048. Epub 2017 Mar 6.
Several problems are associated with corrosion-wear occurring on metal-on-metal hip implants made out of cobalt-chromium based alloys. Low temperature carburizing, a process that creates a hard and corrosion resistant diffused layer in Cobalt-Chromium-Molybdenum (CoCrMo) alloys, known as S-phase, may be a possible solution towards mitigating these problems. In this work, static- and tribo-corrosion testing involving an alumina versus CoCrMo (untreated and carburized) were conducted in Ringer's solution. Electrochemical impedance spectroscopy was used to compare impedance plots attained before and after sliding so as to understand how the metal-electrolyte interface is affected by rubbing. Both untreated and carburized CoCrMo experienced extensive reduction in corrosion resistance following sliding wear damage such that one should expect a considerably deteriorated performance of both surfaces in a tribocorrosion application. The structure of the interface was relatively unaffected after sliding at the equilibrium and passive potentials. This implies that the layers making up the interface before sliding were still present after sliding. However, their properties changed - the interface's real resistance dropped while its capacitance increased. The former was linked to a weaker, damaged passive film while the latter was linked to accumulation of wear debris and corrosion products.
由钴铬基合金制成的金属对金属髋关节植入物会出现一些与腐蚀磨损相关的问题。低温渗碳是一种在钴铬钼（CoCrMo）合金中形成硬且耐腐蚀扩散层（称为S相）的工艺，可能是缓解这些问题的一种解决方案。在这项工作中，在林格氏溶液中进行了涉及氧化铝与CoCrMo（未处理和渗碳）的静态和摩擦腐蚀测试。使用电化学阻抗谱比较滑动前后获得的阻抗图，以了解金属 - 电解质界面如何受到摩擦的影响。未处理和渗碳的CoCrMo在滑动磨损损伤后耐腐蚀性均大幅降低，因此在摩擦腐蚀应用中，预计两个表面的性能都会显著恶化。在平衡电位和钝态电位下滑动后，界面结构相对未受影响。这意味着滑动前构成界面的层在滑动后仍然存在。然而，它们的性能发生了变化——界面的真实电阻下降而电容增加。前者与较弱的、受损的钝化膜有关，而后者与磨损碎片和腐蚀产物的积累有关。
