三维打印技术在柱状晶体结构研究中的应用

APPLICATION OF 3D-PRINTING TECHNOLOGY TO THE STUDY OF COLUMNAR CRYSTALS

等积球体在无限长圆管中的周期性最密堆积结构,可称之为柱状晶体。这类系统的最密结构种类繁多,并随着圆管与球体的直径比D连续变化。在一些较大D值的情况下,晶胞的颗粒数较多,晶胞结构在空间限制的影响下也变得异常复杂。要理解晶胞中每一个球体的排布和它怎样受到其他球体与圆管壁的影响,是一大挑战。本文提出,我们可以通过打印三维实物模型,去窥探复杂晶体结构中球体的空间排布以及球与球之间的接触网络。本文展示,这类柱状晶体结构可以通过熔融沉积成型、光固化快速成型、粉末烧结这三种不同的技术进行三维打印,并仔细讨论每种技术的流程、注意事项、利弊。

Identical hard spheres within an infinitely long cylinder exhibit a great variety of periodic densest possible structures.Such structures,which can be referred to as columnar crystals,generally vary with the diameter ratio D between the confining cylinder and the confined spheres.In some cases with a large value of D,there exist a large number of spheres within the unit cell,and the structure of the unit cell is anomalously complicated as a result of the cylindrical confinement.It would be a great challenge to understand the arrangement of each individual sphere in the unit cell and how each sphere is geometrically influenced by its neighbours and the cylindrical boundary.In this paper,we propose that,by 3D-printing a columnar crystal,one can visualize,with pedagogical benefits,the spatial arrangements of spheres within the crystal structure and the corresponding contact network of spheres.We demon strate that such columnar crystals can respectively be 3D-printed by the methods of Fused Deposition Modelling(FDM),Stereo Lithography Appearance(SLA),and Powder Sintering,with a detailed discussion of the procedure,precautions,advantages and disadvantages of each method.