单喷头多材料电流体动力喷射3D打印机理和规律的研究

Multi-material and multi-scale 3D printing is new frontier in additive manufacturing. The emerging technique has shown great potential to implement the simultaneous and full control for fabricated objects including external geometry, internal architecture, functional surface, material composition and ratio as well as gradient distribution, feature size ranging from nano, micro, to marco-scale, embedded components and electro-circuit, etc. That paves the way and may result in great breakthrough in various applications, e.g., functional tissue and organ, functionally graded material/structure, wearable devices, soft robots, functionally embedded electronics, metamaterial, multi-functionality product, etc. However, there are two challenging issues for current 3D printing processes. One is how to fabricate the heterogeneous and hierarchical structured objects at low cost. The other is that multi-material 3D printing based on the multiple printheads and passive mixing methods has several problems including the complex structure and control, inhomogeneity of mixing multiple materials, low efficiency, limited printing materials. The proposal presents a multi-scale and multi-material 3D printing process with a single printhead. The overall objective of the project is to establish a novel multi-scale and multi-material 3D printing process. Based on the existing research results of applicants, the project focuses on the theoretical basis and key technologies regarding the proposed 3D printing process. It mainly includes following several aspects: (1) the mechanisms and law of the active mixing multi-material printhead; (2) the generation and evolution of nanoliter/ picolicer micro-droplet with multi-material under multi-field condition, the influencing factors and laws for the accurate and DOD deposition of micro-droplet; (3) the surface and interface behaviors and regulatory mechanism for multi-material electrohydrodynamic jet 3D printing; (4) experimental set-up construction, process optimization, and experimental verification for typical applications including variable stiffness models and functionally graded material/structures, etc.

多材料多尺度3D打印是当前增材制造的前沿、研究难点和亟待突破技术。针对目前3D打印面临两个挑战性难题：（1）多材料跨尺度复杂三维结构低成本制造；（2）基于多喷头或材料被动混合的多材料3D打印存在结构控制复杂、材料混合不均匀、效率低、成形材料受限问题。本项目提出一种单喷头多材料主动混合电流体动力喷射3D打印新工艺，旨在发展一种多材料多尺度3D打印新方法。基于课题组前期已有研究成果，项目重点开展单喷头多材料电流体动力喷射3D打印基础理论研究，揭示单喷头多材料电流体动力喷射3D打印成形机理、影响因素和规律。主要研究内容包括：（1）多材料主动混合作用机理及规律；（2）多场作用下多材料纳升/皮升微滴形成和演化机制，微滴精准按需沉积的影响因素和规律；（3）多材料电流体动力喷射3D打印表面/界面行为及调控机制；（4）实验平台搭建、工艺优化以及功能梯度材料/结构模型和变刚度模型等打印实验验证。

多材料多尺度3D打印是当前增材制造的前沿、研究难点和亟待突破技术。针对当前3D打印面临的两个挑战性难题：（1）多材料跨尺度复杂三维结构低成本制造；（2）基于多喷头或材料被动混合的多材料3D打印存在材料混合不均匀、效率低、成形材料受限问题。本项目提出基于多材料主动混合和电场驱动喷射单喷头多材料高分辨3D打印新方法，针对不同材料体系，研发了实现单喷头多材料高分辨3D打印三种新工艺；建立了电流体动力喷射3D打印预估打印点和线宽理论模型；提出基于多材料 3D打印和约束牺牲层的功能梯度材料-结构一体化制造新工艺；揭示多场作用下多材料纳升/皮升微滴形成和演化机制，微滴精准按需沉积的影响因素和规律，实现了最小直径0.9μm微液滴的打印，并将研究成果应用于制造圆形微透镜阵列；创造性提出一种基于单平板电极电场驱动喷射沉积微纳3D打印新工艺，研制出国内首台具有完全自主知识产权的电场驱动喷射沉积微纳3D打印机，打破微纳3D打印被美国、德国、日本等少数国家所垄断，解决了制约我国微纳3D打印“卡脖子”关键技术难题；搭建了实验平台，在高性能透明电加热玻璃、PDMS/SiC功能梯度衬底、高电压功能梯度绝缘子等领域开展了工程应用。本项目实现了预期的目标和成果，为发展我国微纳3D打印这一前沿技术和装备奠定了重要的理论基础。此外，本项目还取得以下重要的成果：在国际顶尖期刊Advanced Materials( IF：30.849）、国内顶尖期刊科学通报、国内权威期刊机械工程学报和中国科学等发表高水平学术论文37篇。其中，2篇国际顶刊，9篇Q1，10篇国内T1。授权美国和中国发明专利26项。制定增材制造国家标准2项。获得山东省高等学校优秀科研成果奖一等奖等3项。美国、瑞典等国际会议邀请报告8次。培养博士后、博士和硕士研究生25人，3人获得山东省优秀硕士学位论文。项目负责人入选2020年国家百千万人才工程，获得国家有突出贡献的中青年专家等人才和荣誉称号。本项目部分研究成果已在军口和民口进行转化与应用。