RMDR Lab, Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, USA.
Orthoillinois, Rockford, IL, USA.
J Mech Behav Biomed Mater. 2022 Oct;134:105402. doi: 10.1016/j.jmbbm.2022.105402. Epub 2022 Aug 11.
Cobalt-chromium-molybdenum (CoCrMo) alloy is one of the most used metals in total hip replacement (THR) due to the alloy's superior corrosion qualities and biocompatibility. Over time these prostheses may undergo wear and corrosion processes in a synergistic process known as tribocorrosion. Implant retrieval studies have shown that damage patterns on THR modular junction surfaces indicating specifically in vivo fretting-corrosion to take place. To date, there have been no studies on the fretting-corrosion behaviors of CoCrMo alloy under the consideration of specific microstructural features. A custom-built flat-on-flat fretting-corrosion setup was utilized to test the synergistic tribocorrosion behavior of fretting-corrosion. The difference in microstructure was generated through the cutting orientations of the transverse and the longitudinal direction of the bar stock material, where the longitudinal cut exhibits a characteristic banded microstructure (banded group) and the transverse cut a homogenous microstructure (unbanded group). A three-electrode system was employed to monitor the induced currents. Two different types of electrolytes were used in the current study: 1. Bovine calf serum (BCS-30 g/L protein) (normal conditions) 2. BCS with Lipopolysaccharide (LPS, 0.15 μg/ml) (simulated infectious conditions). In the free potential mode, banded samples showed an increased potential compared to the unbanded samples. In potentiostatic conditions, the banded group also exhibited a higher induced current in both electrolyte environments, indicating more corrosion loss. Both Nyquist and Bode plots showed both orientations of metal becoming more corrosion resistant post-fretting when compared to pre-fretting data. The longitudinal group at OCP demonstrated a unique shape of the fretting-loop, which might be related to tribochemical reactions. Based on the mechanical, electrochemical, and surface characterization data, the transverse group (unbanded) microstructures demonstrates a higher resistance to fretting-corrosion damage.
钴铬钼（CoCrMo）合金由于其优异的耐腐蚀性和生物相容性，是全髋关节置换术（THR）中使用最广泛的金属之一。随着时间的推移，这些假体可能会在一个协同的过程中经历磨损和腐蚀，这个过程被称为摩擦腐蚀。植入物回收研究表明，THR 模块连接面的损伤模式表明体内微动腐蚀确实在发生。迄今为止，还没有研究考虑特定微观结构特征时 CoCrMo 合金的微动腐蚀行为。本研究采用定制的平面对平面微动腐蚀装置来测试微动腐蚀的协同摩擦腐蚀行为。通过棒材材料的横向和纵向切割方向来产生微观结构的差异，其中纵向切割显示出特征带状微观结构（带状组），而横向切割则呈现均匀的微观结构（无带状组）。采用三电极系统来监测感应电流。本研究使用了两种不同类型的电解质：1. 牛犊血清（BCS-30g/L 蛋白）（正常条件）2. 含脂多糖（LPS，0.15μg/ml）的 BCS（模拟感染条件）。在自由电位模式下，带状样品的电位比无带状样品高。在恒电位条件下，在两种电解质环境中，带状组也表现出更高的感应电流，表明腐蚀损失更大。奈奎斯特和波特图都显示，与预微动数据相比，两种取向的金属在微动后都具有更高的耐腐蚀性。在 OCP 时，纵向组表现出独特的微动环形状，这可能与摩擦化学有关。基于力学、电化学和表面特性数据，横向组（无带状）的微观结构显示出对微动腐蚀损伤更高的抵抗力。
