Shin Chow Shing, Chang Yu Chia
Department of Mechanical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.
Polymers (Basel). 2021 Mar 4;13(5):785. doi: 10.3390/polym13050785.
Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.
晶格结构在力学性能方面优于随机泡沫，并且其应用越来越广泛。通过调整晶胞的设计和尺寸、改变组成材料以及形成分级结构，可以在很大范围内对其性能进行定制。为了实现更高层次的分级，基本晶格的尺寸必须足够小。尽管使用双光子聚合技术可以制造出几微米的晶格尺寸，但需要复杂且昂贵的设备。为了平衡成本和性能，在这项工作中基于商用数字光处理（DLP）投影仪开发了一种低成本高分辨率微立体光刻系统。已经成功制造出小至100μm的晶胞长度。将晶胞尺寸从150μm减小到100μm，压缩刚度提高了26%。已经尝试了不同的预处理方法以促进在晶格结构上进行化学镀镍。在石墨烯悬浮液中浸涂的预处理最为成功，强度和刚度分别提高了5.3倍和3.6倍。即使内部的镀镍非常轻且不完全，结构刚度和强度也提高了两倍多。
