Cellular Metals Manufacturing

Open cell, stochastic nickel foams are widely used for the electrodes and current collectors of metal – metal hydride batteries. Closed cell, periodic aluminum honeycomb is extensively used for the cores of light, stiff sandwich panel structures. Interest is now growing in other cell topologies and potential applications are expanding. For example cellular metals are being evaluated for impact energy absorption, for noise and vibration damping and for novel approaches to thermal management. Numerous methods for manufacturing cellular metals are being developed. As a basic understanding of the relationships between cell topology and the performance of cellular metals in each application area begins to emerge, interest is growing in processes that enable an optimized topology to be reproducibly created. For some applications, such as acoustic attenuation, stochastic metal foams are likely to be preferred over their periodically structured counterparts. Nonetheless, the average cell s ize, the cell size standard deviation, the relative density and the microstructure of the ligaments are all important to control. The invention of more stable processes and improved methods for on‐line control of the cellular structure via in‐situ sensing and more sophisticated control algorithms are likely to lead to significant improvements in foam topology. For load supporting applications, sandwich panels containing honeycomb cores are much superior to those utilizing stochastic foams, but they are more costly than stochastic foam core materials. Recently, processes have begun to emerge for making open cell periodic cell materials with triangular or pyramidal truss topologies. These have been shown to match the stiffness and strength of honeycomb in sandwich panels. New cellular metals manufacturing processes that use metal textiles and deformed sheet metal are being explored as potentially low cost manufacturing processes for these applications. These topologically optimized systems are opening up new multifunctional applications for cellular metals.     

多孔金属材料的应用

本文综合介绍了多孔金属材料的应用,目的在于促进该材料性能结构的进一步改善,并获得更好的应用前景。     

生物医用多孔金属材料的研究进展

本文综述了生物医用多孔金属材料在制备工艺、力学性能、耐蚀性及生物相容性方面的研究进展。作为一种新型的硬组织修复材料 ,生物医用多孔金属材料以其优良的生物相容性在矫形外科、牙科等医疗领域有广阔的应用前景     

Solid State Porous Metal Production: A Review of the Capabilities,Characteristics, and Challenges

Porous metals have been under development for nearly a century, but commercial adoption remains limited. This development has followed two primary routes: liquid state or solid state processing. Liquid state foaming introduces porosity to a liquid or semi‐solid metal, and solid state foaming introduces porosity to a metal, which is fully solid. Either method may create pores by internal gas pressure or introducing metal around a template directly control porosity. Process optimization and commercial output has been primarily related to liquid state methods, as solid state processing is often more complex, diverse, and with lower throughput. Solid state methods, however, are often more versatile and offer greater control of pore characteristics. Ongoing advancements in solid state foaming have allowed for a wide array of metals and alloys to be made porous and the three‐dimensional structure to be precisely tailored. In general, solid state processing remains limited to niche applications, often with modest dimensions (cm scale). “Traditional” solid state processes are being further refined and extended, and continuing developments to reduce cost, increase output, and control pore characteristics are likely to produce important advancements in coming years. The extensive variability of pore quantity and morphology makes solid state processes suitable, and often preferable, for an assortment of functional and structural applications, with electrodes and biomedical devices being among the most popular in current research. Various techniques for introducing porosity, the way these methods are applied, important considerations, typical outcomes, and current applications are reviewed.

     

Recent Advances of Porous Graphene: Synthesis,Functionalization, and Electrochemical Applications

Graphene is a 2D sheet of sp² bonded carbon atoms and tends to aggregate together, due to the strong π–π stacking and van der Waals attraction between different layers. Its unique properties such as a high specific surface area and a fast mass transport rate are severely blocked. To address these issues, various kinds of 2D holey graphene and 3D porous graphene are either self‐assembled from graphene layers or fabricated using graphene related materials such as graphene oxide and reduced graphene oxide. Porous graphene not only possesses unique pore structures, but also introduces abundant exposed edges and accelerates mass transfer. The properties and applications of these porous graphenes and their composites/hybrids have been extensively studied in recent years. Herein, recent progress and achievements in synthesis and functionalization of various 2D holey graphene and 3D porous graphene are reviewed. Of special interest, electrochemical applications of porous graphene and its hybrids in the fields of electrochemical sensing, electrocatalysis, and electrochemical energy storage, are highlighted. As the closing remarks, the challenges and opportunities for the future research of porous graphene and its composites are discussed and outlined.     

基于二维Voronoi模型的多孔泡沫金属导热性能模拟研究

多孔金属材料作为新型功能材料具有密度低、强度高、导热性能优良等特性,应用前景广阔,受到越来越多的关注。多孔材料的有效导热系数与随机孔隙结构相关,仅用孔隙率不足以描述真实材料的孔隙结构。采用二维Voronoi模型,定义孔隙随机度S和孔隙率ε作为孔隙结构参数,通过调节核点位置偏移因子α和边宽系数β改变模型的随机度S和孔隙率ε,分析随机度S和孔隙率ε对相对有效导热系数k*的影响。结果表明,随机度和孔隙率同时影响多孔泡沫材料的有效导热系数,当随机度S一定时,随着孔隙率ε增大,材料的有效导热系数k*减小;当孔隙率ε一定时,随着随机度S的增大,有效导热系数k*减小。根据大样本的有限元数值模拟结果,拟合了有效导热系数由孔隙率和随机度组成的函数表达式。     

多孔金属膜研究进展

通过多孔金属膜与有机膜和陶瓷膜的对比,阐述了多孔金属膜的优点,金属膜的发展及现状,重点阐述了多孔金属膜的制备方法,并对这几种制备方法进行了分析、比较.最后简要介绍了多孔金属膜的发展动态及趋势.     

泡沫金属中池沸腾传热的研究进展

介绍了泡沫金属的结构特性,总结了泡沫金属中池沸腾的气泡生长速度、气泡直径和气泡生长现象等传热特点,以及泡沫金属的孔隙率、孔密度等参数对池沸腾传热的影响,并指出了泡沫金属中沸腾传热的研究方向。