Mathew M T, Runa M J, Laurent M, Jacobs J J, Rocha L A, Wimmer M A
Section of Tribology, Department of Orthopedic Surgery, Rush University Medical Center, 60612 Chicago, IL, USA.
Wear. 2011 Jul 29;271(9-10):1210-1219. doi: 10.1016/j.wear.2011.01.086.
Metal-on-metal (MOM) hip prosthesis bearings have enjoyed renewed popularity, but concerns remain with wear debris and metal ion release causing a negative response in the surrounding tissues. Further understanding into the wear and corrosion mechanisms occurring in MOM hips is therefore essential.The purpose of this study was to evaluate the tribocorrosion behaviour, or interplay between corrosion and wear, of a low-carbon CoCrMo alloy as a function of loading. The tribocorrosion tests were performed using two tribometer configurations. In the first configuration, "System A", a linearly reciprocating alumina ball slid against the flat metal immersed in a phosphate buffer solution (PBS). In the second configuration, "System B", the flat end of a cylindrical metal pin was pressed against an alumina ball that oscillated rotationally, using bovine calf serum (BCS) as the lubricant and electrolyte. System B was custom-built to emulate in vivo conditions. The tribocorrosion tests were performed under potentiostatic conditions at -0.345V, with a sliding duration of 1800 seconds and a frequency of 1Hz. In System A the applied loads were 0.05, 0.5, and 1N (138, 296 and 373MPa, respectively) and in System B were 16, 32, and 64N (474, 597, and 752MPa, respectively). Electrochemical impedance spectroscopy (EIS) and polarization resistance were estimated. The total mass loss (K(wc)) in the CoCrMo was determined. The mass loss due to wear (K(w)) and that due to corrosion (K(c)) were determined. The dominant wear regime for the CoCrMo alloy subjected to sliding changes from wear-corrosion to mechanical wear as the contact stress increases. An attempt was made to compare both system, in their tribochemical responses and formulate some insights in the total degradation processes. Our results also suggest that the proteins in the serum lubricant assist in the generation of a protective layer against corrosion during sliding. The study highlights the need of adequate methodology/guidelines to compare the results from different test systems and translating in solving the practical problems.
金属对金属（MOM）髋关节假体轴承再度受到欢迎，但人们仍担心磨损碎屑和金属离子释放会对周围组织产生负面反应。因此，进一步了解MOM髋关节中发生的磨损和腐蚀机制至关重要。本研究的目的是评估一种低碳CoCrMo合金的摩擦腐蚀行为，即腐蚀与磨损之间的相互作用，作为载荷的函数。摩擦腐蚀试验使用两种摩擦计配置进行。在第一种配置“系统A”中，一个线性往复运动的氧化铝球在浸入磷酸盐缓冲溶液（PBS）的平面金属上滑动。在第二种配置“系统B”中，圆柱形金属销的平端压在一个旋转振荡的氧化铝球上，使用小牛血清（BCS）作为润滑剂和电解质。系统B是为模拟体内条件而定制的。摩擦腐蚀试验在-0.345V的恒电位条件下进行，滑动持续时间为1800秒，频率为1Hz。在系统A中，施加的载荷为0.05、0.5和1N（分别为138、296和373MPa），在系统B中为16、32和64N（分别为474、597和752MPa）。估计了电化学阻抗谱（EIS）和极化电阻。测定了CoCrMo中的总质量损失（K（wc））。确定了磨损引起的质量损失（K（w））和腐蚀引起的质量损失（K（c））。随着接触应力的增加，CoCrMo合金在滑动时的主要磨损机制从磨损腐蚀转变为机械磨损。试图比较两个系统的摩擦化学响应，并对总降解过程形成一些见解。我们的结果还表明，血清润滑剂中的蛋白质有助于在滑动过程中生成抗腐蚀保护层。该研究强调了需要适当的方法/指南来比较不同测试系统的结果，并将其转化为解决实际问题的方法。
