金属纤维多孔材料孔结构形成机制及冲击动力学行为研究

Porous materials of metal fiber, which is a new type of light weight porous metal materials, is widely used in the fields of aerospace, high-speed train, automobile, packaging, transportation and so on for excellent absorption impact energy. The pore structure is the key factor influencing absorption effect of impact energy for porous materials, but also greatly affects its dynamic deformation behavior and damage process, while research in the respect has not been reported. In the project, the fiber of 316L with the diameter from ?8μm to ?28μm was used to fabricate porous materials of metal fiber using vacuum sintering technique. The effects of sintering process (i.e. sintering temperature, pressure and holding time), the diameter and the surface state of fiber, the thickness and the porosity of porous materials on the formation process and mechanism of pore structure were studied. Furthermore, the effects of the pore structure and the strain rate on the dynamic compressive property of porous materials were investigated under the condition of impact load, and then the deformation behavior and the damage mechanism of porous materials were elucidated by discussing the deformation and damage processes. In addition, the effect of pore structure on the propagation and attenuation processes of stress wave was analyzed and the mechanism was also investigated, and then the preparation technology of porous materials was optimized. The studying of the program has not only important academic value and theoretical significance for enriching materials science, physical metallurgy and impact dynamics, but also has significant practical value for improving the performance of porous materials of metal fiber.

金属纤维多孔材料是一类新型轻质金属多孔材料，具有优异的冲击能量吸收能力而广泛应用于航空航天、高速列车、汽车、包装、运输等领域。孔结构是影响多孔材料冲击能量吸收效果的关键因素，而且也会对其动态变形行为与损伤过程产生重要影响，而关于这方面的研究未见报道。本项目以?8-?28μm的316L纤维为原料，采用真空烧结技术制备金属纤维多孔材料，研究烧结工艺（烧结温度、压力、保温时间）、纤维直径、纤维表面状态、材料厚度及孔隙率等对孔结构形成过程的影响规律，揭示孔结构形成机制；研究应变率与孔结构对多孔材料动态压缩性能的影响规律，探讨多孔材料的变形与损伤过程，阐明其变形行为及损伤机理；研究孔结构对应力波传播及衰减过程的影响规律，揭示其传播与衰减机制，优化多孔材料的制备工艺。开展本项目不仅对丰富材料学、物理冶金学和冲击动力学具有重要的学术价值和理论意义，而且对提高金属纤维多孔材料性能具有显著的实际应用价值。

本项目在国家自然科学基金（51301141）的资助下，开展了金属纤维多孔材料制备、孔结构形成过程及形成机制分析、动态冲击性能及应力波传播规律等研究，全面完成了各项研究内容。. 本项目以冲击防护领域对高效能量吸收、高效减振降噪的轻质纤维多孔材料需求为牵引，以丝经为Ø8µm、Ø12µm、Ø20µm和Ø28µm的金属纤维毛毡为原料，采用真空烧结技术制备了孔隙率为65% ~ 90%的烧结金属纤维多孔材料，系统分析了烧结工艺、纤维直径、纤维表面状态、材料厚度及孔隙率等因素对孔结构形成过程的影响规律，揭示了孔结构的形成机制。研究了金属纤维多孔材料在不同应变率下的动态冲击性能，探讨了金属纤维多孔材料的动态变形行为，分析了纤维直径、材料孔隙率对屈服强度和能量吸收值的影响规律，即孔隙率低于75%时，纤维直径为Ø8µm ~ Ø12µm的烧结金属纤维多孔材料的屈服强度和能量吸收值较高；孔隙率超过80%时，纤维直径为Ø28µm的烧结金属纤维多孔材料的屈服强度和能量吸收值最高。揭示了应力波在多孔材料内部的传播规律和衰减机制，即应力波波形包括入射波、反射波和透射波；金属纤维直径对应力波波形的影响不显著；孔隙率对应力波的影响存在波动。进一步优化了金属纤维多孔材料的制备工艺，实现了多孔材料对冲击能力的高效吸收。. 本项目共发表论文6篇（SCI收录4篇），申请专利1项，培养硕士研究生1名。. 本项目的研究成果可用于制备具有高效能量吸收特性的金属纤维多孔材料，并将其推广应用到冲击防护领域。