Abstract

Magnesium and its alloys have great capability for degradation in the body in a natural way, so they are one of the main new candidates as biodegradable implant materials. Of course, one of the disadvantages of pure Mg is its rapid degradation in the physiological environment that prior to bone healing has a negative impact on its mechanical integrity. In the present paper, a semipowder metallurgy coupled with hot extrusion process was utilized to fabricate Mg-6Zn/xGO (0.2 and 0.4 wt %) biocomposite. According to the microstructural characterization, graphene oxide (GO) nanosheets had uniform distribution in the composite, and also partial and gradually wrapped α-Mg grains were observed inside the Mg matrix. Results showed that the hardness and compressive yield of the Mg-6Zn/xGO composite were notably higher in comparison to pure Mg. It was revealed that the mechanical properties were enhanced because of the mechanisms of crack bridging, crack deflection, and crack tip shielding. The H₂ evolution throughout their immersion in simulated body fluid (SBF) was decreased remarkably because GO nanosheets were distributed uniformly in the Mg matrix. In addition, less corrosion current density and higher corrosion resistance of the extruded Mg-6Zn and Mg-6Zn/GO in comparison to pure Mg were shown by electrochemical tests. Since the rate of the degradation process was decreased, the extruded Mg-6Zn/GO biocomposite presented great cytocompatibility. The research results show that GO nanosheets are efficient reinforcement to fabricate the extruded Mg-6Zn/GO biocomposite, which leads to the improvement of mechanical, corrosion and biological properties.

中文翻译：

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用于植入物的低氧化石墨烯热挤压镁锌纳米复合材料的合成与表征

摘要

镁及其合金在体内具有很强的自然降解能力，因此它们是可生物降解的植入材料的主要新候选材料之一。当然，纯镁的缺点之一是它在生理环境中的快速降解，在骨愈合之前对其机械完整性产生负面影响。在本文中，利用半粉末冶金与热挤压工艺相结合来制造 Mg-6Zn/ x GO（0.2 和 0.4 重量％）生物复合材料。根据微观结构表征，氧化石墨烯（GO）纳米片在复合材料中分布均匀，并且在镁基体内部观察到部分和逐渐包裹的α-镁颗粒。结果表明,Mg-6Zn/ x的硬度和压缩屈服与纯镁相比，GO 复合材料明显更高。结果表明，由于裂纹桥接、裂纹偏转和裂纹尖端屏蔽机制，机械性能得到了增强。H ₂由于 GO 纳米片均匀分布在 Mg 基质中，因此它们在模拟体液 (SBF) 中的整个浸泡过程中的演化显着减少。此外，电化学测试表明，与纯镁相比，挤压成型的 Mg-6Zn 和 Mg-6Zn/GO 具有更低的腐蚀电流密度和更高的耐腐蚀性。由于降解过程的速率降低，挤出的 Mg-6Zn/GO 生物复合材料表现出很好的细胞相容性。研究结果表明，GO纳米片可有效增强挤压成型的Mg-6Zn/GO生物复合材料，从而提高机械、腐蚀和生物学性能。