Cobalt-based alloys, such as cobalt-chromium-molybdenum (CoCrMo), are known for their high mechanical strength and find extensive applications in the biomedical field such as manufacturing of tools, dental components, and orthopedic implants. The longevity of the CoCrMo alloy in service is intricately linked to its resistance to corrosion and wear. Specifically, tribocorrosion can contribute to material loosening; therefore, it is essential to explore surface treatments for cobalt-based alloys as a means to enhance their wear resistance, ensuring the prolonged durability of the material. This study provides novel insights into the bio-tribocorrosion resistance of the borided CoCrMo alloy when immersed in calf serum, emulating the synovial fluid. Two distinct microstructures of boride layers were examined in this research: (1) a CoB–Co2B layer formed through powder-pack boriding and (2) the borided surface underwent diffusion annealing to completely dissolve the CoB, resulting in a monophasic layer (Co2B). Following the ASTM G119-09 procedure, the total material loss (T), encompassing both material loss due to wear (WC) and corrosion (CW), was determined using a linear reciprocating ball-on-flat tribometer equipped with an electrochemical cell. Test results indicated that the presence of CoB–Co2B and Co2B layers on the CoCrMo alloy increased bio-tribocorrosion resistance approximately 2.4 times and 1.3 times, respectively, compared to the non-treated CoCrMo alloy. A dominant wear regime was observed for the borided surface exposed to diffusion annealing and the non-treated CoCrMo alloy, whereas the borided CoCrMo alloy exhibited a corrosion-wear regime. Clearly, these findings highlight the capability of the cobalt boride layer to improve the performance and extend the service life of the CoCrMo alloy in biomedical applications.

中文翻译：

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CoCrMo合金上CoB-Co2B和Co2B层的生物摩擦腐蚀性能

钴基合金，例如钴铬钼 (CoCrMo)，以其高机械强度而闻名，在生物医学领域有着广泛的应用，例如工具、牙科组件和骨科植入物的制造。CoCrMo 合金的使用寿命与其耐腐蚀和耐磨性密切相关。具体来说，摩擦腐蚀会导致材料松动；因此，有必要探索钴基合金的表面处理方法，以提高其耐磨性，确保材料的长期耐用性。这项研究为硼化 CoCrMo 合金浸入小牛血清（模拟滑液）时的生物摩擦腐蚀性能提供了新的见解。本研究检查了硼化物层的两种不同的微观结构：(1) 通过粉末包硼化形成的 CoB-Co2B 层，以及 (2) 硼化表面经过扩散退火以完全溶解 CoB，从而形成单相层 (Co2B) 。按照 ASTM G119-09 程序，使用配备电化学电池的线性往复球平摩擦磨损计测定总材料损失 (T)，包括由于磨损 (WC) 和腐蚀 (CW) 导致的材料损失。测试结果表明，CoCrMo 合金上存在 CoB-Co2B 和 Co2B 层，与未经处理的 CoCrMo 合金相比，其生物摩擦腐蚀性能分别提高了约 2.4 倍和 1.3 倍。对于暴露于扩散退火的硼化表面和未经处理的 CoCrMo 合金观察到主要磨损状态，而硼化 CoCrMo 合金表现出腐蚀磨损状态。显然，这些发现凸显了硼化钴层在生物医学应用中提高 CoCrMo 合金性能并延长其使用寿命的能力。