Combinatorial Additive Manufacturing Approach for Fabricating Nano/Micro 3D Structures

在自由空间中制造三维结构对于制造某些小型化器件是非常重要的。通常被称为3D打印的增材制造对于推进这一领域至关重要。在过去的三十年里，人们探索了使用金属、陶瓷和聚合物制造复杂零件的增材制造方法。然而，这些方法中的许多方法可以在固定尺寸上制造结构，而对局部成分和微观结构的控制最小。这限制了它们在制造需要局部地形变化的新型设备时的适用性。本研究旨在开发一种结合微挤压和液滴制备方法的复合增材工艺。该混合制造方法将能够根据应用意图制造具有可控密度、材料含量、晶格结构、孔隙率和几何构型的结构。典型的应用包括组织工程支架、高性能能源设备和航空航天部件的嵌入式电子设备。这项研究将通过刺激工业部门的就业机会，对美国经济产生积极影响，并导致学术和研究界的基本过程调查。这项研究将影响在一所历史悠久的黑人大学中以发现为基础的先进制造方法学习中代表性不足的学生。本研究探讨了基于长丝微挤压和基于液滴制造相结合的分层纳米/微结构的增材制造。本研究的目标包括：(1)利用混合方法理解微纳结构的形成；(2)研究材料的长丝挤压、纳米/微滴沉积、激光照射和凝固；(3)通过混合工艺试验设计，建立相互作用工艺参数之间的关系。微挤压工艺将用于根据喷嘴尺寸沉积微尺度细丝的材料。基于可扩展的直接写入制造方法，这些长丝晶格结构将沉积在纳米到微米尺寸的液滴上。液滴的含量范围可以从熔融金属、聚合物到纳米颗粒溶液，其作为一种有效的方法来渗透长丝的选择区域，以产生所需的微观结构和材料性能。采用高功率CO2激光系统对沉积结构进行多层选择性烧结，生成三维零件。利用有限元分析和分子动力学模型，将开发计算模型来研究微丝结构与微纳米液滴相互作用过程中有趣的多物理场现象。

The fabrication of three dimensional structures in free space is important for building certain miniaturized devices. Additive manufacturing popularly called as 3D printing is critical in advancing this field. Over the past three decades additive manufacturing methods have been explored to build complex parts using metals, ceramics and polymers. However, many of these methods can fabricate structures at a fixed dimension with minimal control on the local composition and microstructure. This limits their applicability to the manufacturing of novel devices which require variation in local topography. This research aims to develop a combinatorial additive process by combining microextrusion and droplet based fabrication methods. The hybrid manufacturing method will enable the fabrication of structures that have controlled density, material content, lattice structure, porosity and geometrical configuration based on the application intent. Typical applications include tissue engineering scaffolds, high performance energy devices, and embedded electronics for aerospace components. This research will positively impact the US economy by spurring jobs within the industrial sector and lead to fundamental process investigations within the academic and research communities. This research will impact underrepresented students in discovery based learning of advanced manufacturing methods at a historically black university. This research investigates the additive manufacturing of hierarchical nano/microstructures using a combination of filament based micro extrusion and droplet based manufacturing. The objectives of this research include: (1) understanding micro/nano structure formations using the hybrid approach; (2) studying the filament extrusion, nano/micro droplet deposition, laser irradiation and solidification of materials; and (3) establishing relationships among interacting process parameters by experimental design of hybrid process. The micro extrusion process will be employed to deposit microscale filaments of material based on the nozzle size. These filament lattice structures will be deposited with droplets ranging from nano to micro size based on a scalable direct-write manufacturing method. The droplet content can range from molten metal, polymers to nanoparticle solutions which serve as an effective method to infiltrate selective regions of the filament to produce the desired microstructure and material property. High power CO2 laser system will be used to selectively sinter the deposited structures in multiple layers to generate a 3D part. Using finite element analysis and molecular dynamics models, computational models will be developed to study intriguing multiphysics phenomena during the interaction of micro filament structures with micro and nano droplets.