Department of Automotive Engineering, School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; Advanced Vehicle Research Center (AVRC), Beihang University, Beijing 100191, China; State Key Laboratory for Strength & Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Department of Automotive Engineering, School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; Advanced Vehicle Research Center (AVRC), Beihang University, Beijing 100191, China.
J Mech Behav Biomed Mater. 2019 Jun;94:10-18. doi: 10.1016/j.jmbbm.2019.02.029. Epub 2019 Mar 1.
Natural structural materials featuring fine hierarchical architectures often display remarkable mechanical properties. To inherit the microstructures of biological materials, nickel-plated luffa sponges were fabricated through electrochemical deposition using natural luffa sponges as templates. Four groups of samples were processed based on nickel electroless and electroplating, and then characterized by X-ray diffraction and optical/scanning electron microscopy. Axial compression tests were performed to characterize the mechanical properties of the nickel-plated samples to compare with those of the original natural sponges. Results showed that a uniform layer of nickel was formed on the luffa fibers by electroless plating; conversely, by electroplating the nickel only minimal deposits were found on the inner luffa wall due to the uneven current distribution over the surface of sponge. Accordingly, electroless plating was deemed to be far more effective for metal deposition of materials with complex structures, such as luffa sponge. Alkali treatments prior to plating were found to be critical for subsequent mechanical performance and energy absorption capacity. The mechanical properties of nickel-plated samples surpass those of original luffa sponges, with the enhancement efficiency, i.e., the ratio of specific stiffness and strength, being highest for electroless-plated samples with a prior alkali treatment. Specifically, their energy absorption capacity was far superior to that in other comparable materials. Using a power scaling law, an empirical relationship was derived which indicated that the bending-dominated behavior of the nickel-plated luffa sponges was similar to that of open-cell foams. We believe that other artificially "bio-inherited materials" could be successfully processed and developed in this manner. The superior properties of bio-inherited materials that we obtained in this work may provide inspiration for future research efforts on bio-inspired structural materials.
具有精细分级结构的天然结构材料通常表现出显著的机械性能。为了继承生物材料的微观结构，采用电化学沉积法，以天然丝瓜络为模板，制备了镀镍丝瓜络。根据化学镀和电镀，加工了四组样品，并通过 X 射线衍射和光学/扫描电子显微镜进行了表征。对镍镀层样品的力学性能进行了轴向压缩试验，以与原始天然海绵进行比较。结果表明，通过化学镀在丝瓜络纤维上形成了均匀的镍层；相反，通过电镀，由于表面电流分布不均匀，仅在内丝瓜络壁上发现了最小的镍沉积物。因此，化学镀被认为对于具有复杂结构的材料（如丝瓜络）的金属沉积更为有效。镀前碱处理被发现对后续的机械性能和能量吸收能力至关重要。镍镀层样品的力学性能优于原始丝瓜络海绵，其中经过碱处理的化学镀样品的增强效率（即比刚度和强度比）最高。具体而言，它们的能量吸收能力远远优于其他可比材料。通过功率缩放定律，推导出了一个经验关系，表明镀镍丝瓜络海绵的弯曲主导行为与开孔泡沫相似。我们相信，其他人工“生物遗传材料”可以以这种方式成功加工和开发。我们在这项工作中获得的生物遗传材料的优异性能可能为未来对仿生结构材料的研究提供启示。
