阳离子光固化高性能墨水直写浆料的研制

阳离子光固化材料通常具有低收缩、化学稳定性好、高力学性能等优点。为发展阳离子光固化型墨水直写打印技术（DIW）,以双酚A二缩水甘油醚（DGEBA）为主体树脂,通过对触变剂、光引发剂和活性稀释剂的研究制备了一系列阳离子DIW打印浆料,并研究了该体系浆料的可打印性以及力学性能。结果表明,气相二氧化硅的添加可以有效调节浆料流变性能,使其满足DIW打印要求。当异丙基硫杂蒽酮（ITX）与二甲苯基碘鎓六氟磷酸盐（IOD（）摩尔比1:1）组成的光引发体系添加量为3%时,浆料固化速度最快。拉伸性能表征发现,打印样条的断裂伸长率随着OXT-BZ稀释剂的增加而增加,且拉伸强度保持在40 MPa以上,表现出优异的力学性能。通过对打印沟环器件的负载测试发现,该浆料对玻璃、铝合金等基材具有优异的附着性,可实现8 kg砝码的负载,展现了优异的力学性能。     

阳离子光固化高性能墨水直写浆料的研制EI

阳离子光固化材料通常具有低收缩、化学稳定性好、高力学性能等优点。为发展阳离子光固化型墨水直写打印技术(DIW),以双酚A二缩水甘油醚(DGEBA)为主体树脂,通过对触变剂、光引发剂和活性稀释剂的研究制备了一系列阳离子DIW打印浆料,并研究了该体系浆料的可打印性以及力学性能。结果表明,气相二氧化硅的添加可以有效调节浆料流变性能,使其满足DIW打印要求。当异丙基硫杂蒽酮(ITX)与二甲苯基碘鎓六氟磷酸盐(IOD)(摩尔比1:1)组成的光引发体系添加量为3%时,浆料固化速度最快。拉伸性能表征发现,打印样条的断裂伸长率随着OXT-BZ稀释剂的增加而增加,且拉伸强度保持在40 MPa以上,表现出优异的力学性能。通过对打印沟环器件的负载测试发现,该浆料对玻璃、铝合金等基材具有优异的附着性,可实现8 kg砝码的负载,展现了优异的力学性能。     

直写3D打印陶瓷基多孔结构的研究进展

陶瓷基多孔结构既继承致密陶瓷材料耐高温、电绝缘、化学稳定的优异性能,又兼具多孔结构低密度、高比表面积、低热导率的独特优势,已被广泛应用于隔热、骨组织工程、过滤及污染物清除、电子元器件等领域。但是,陶瓷基多孔结构的传统成孔方法在宏观尺度创造复杂几何外形与微纳尺度调控孔结构形态方面仍面临巨大挑战。近几十年来,研究人员一直致力于创新陶瓷基多孔结构的加工成型方法,以直写3D打印为代表的增材制造技术成为当前研究的热点,并迅速发展出一系列成熟理论与创新方法。本文首先概述了陶瓷基多孔结构的传统成孔方法与增材制造成孔方法,进一步详细介绍了直写组装成孔工艺过程,主要包括假塑性墨水配方、固化策略、干燥及后处理,分析了传统成孔方法与直写3D打印二者的组合技术在构筑陶瓷基多级孔结构方面的可行性,总结了直写3D打印技术在制造复杂陶瓷基多孔结构领域的新观点、新进展和新发现,最后结合陶瓷基多孔结构实际应用现状对直写3D技术的未来发展与挑战进行了展望。     

适用于直写式3D打印陶瓷浆料的流变学性能研究

目的 提出用于直写式3D打印陶瓷浆料的制备方法 和应满足的性能.方法 通过对4种不同陶瓷原料粉末的粒径分布进行表征,将4种粉末制备成浆料并测量其流变学性能,分析不同阶段高分子的引入对浆料流变学性能的影响.结果 对于较小孔径(250μm和150μm)的打印过程,原料粉末粒径绝对值需小于3μm且d90和d10的差值需小于2...     

木质素基复合材料的直写式3D打印及其功能应用

作为自然界最丰富的可再生芳香族生物质资源,木质素近年来在能源、环境、医学等领域受到广泛关注。其中,采用3D打印技术构建具有特定结构和功能的木质素基复合材料是提升木质素附加值的重要途径之一,同时可有效避免木质素化学结构复杂多变、多分散性高、刚性大等在传统材料制备过程中带来的负面影响。本文围绕木质素基复合材料的直写式3D打印,重点综述了近年来木质素基复合材料在直写式3D打印方面的研究成果与进展。首先介绍了木质素的结构特性及直写式3D打印技术;然后系统总结了木质素流变学特性与其打印性能之间的构-效关系;最后讨论了3D打印的木质素基复合材料在能源、环境等领域的应用现状及其面临的挑战,并展望了木质素基复合材料在直写式3D打印方面的发展方向。     

3D打印磁控柔性抓手

柔性抓手能够在外部刺激下发生形变,在货物运输等领域有较好的应用。然而,目前使用的柔性抓手响应速度慢,对货物的形态和质量都有着较高要求,无法像人手一样适配绝大多数场景,因此有必要开发一种响应速度快、适配各种货物的柔性抓手。本文将硬磁材料--钕铁硼粉末(NdFeB)与硅橡胶(Room temperature vulcanized rubber,RTV橡胶)进行共混复合,形成了一种可打印的磁响应NdFeB-RTV橡胶复合材料。通过对墨水直写3D打印技术的制造工艺参数的探索和优化,将NdFeB-RTV橡胶复合材料的前驱体墨水打印成型。该材料固化后呈现出优异的力学性能-断裂伸长率接近300%,抗拉强度为1.03 MPa,拉伸杨氏模量为1.27 MPa,弯曲强度为78.06 MPa,弯曲模量为160.96 MPa。最后,本文采用墨水直写3D打印技术,设计制造了磁响应的四臂抓手机器人。利用机器人的磁致动与柔韧特性,实现了灵活变形、快速抓取、平稳运输等功能。     

吸热墨水喷射3D打印高分子材料的研究现状与发展趋势

吸热墨水喷射3D打印技术可高效率成形复杂高性能塑料零件,对推动3D打印技术批量化应用具有积极意义。文中以惠普公司的多射流熔融技术和维捷公司的高速烧结技术为主综述了吸热墨水喷射3D打印的技术原理、发展历程和应用领域,总结了材料与工艺因素对其成形质量的影响,概述了吸热墨水喷射3D打印材料体系及相应3D打印研究的进展。通过分析该技术目前面临的主要问题,对其未来重点研究方向进行了展望。     

基于打印参数影响的3D打印混凝土力学性能试验研究

本工作制备了具有良好工作性能的3D打印混凝土,研究了喷头尺寸、打印路径两类打印参数对试件抗压强度、抗弯强度、微观和细观结构的影响,重点分析了其受力开裂的破坏机理,并且基于孔隙结构参数提出了抗压强度预测模型。结果表明：随着喷头尺寸由20 mm增大至40 mm, 3D打印混凝土的可建造性增强,打印试件的力学强度提升7.5%～31.6%,孔隙率和缺陷数量下降;正交路径B的打印试件孔隙率与平行路径A的相近,但其力学强度提升10.8%～46.7%。3D打印混凝土最薄弱界面是打印层间界面;打印试件开裂破坏时有三类破坏形态出现;建立的3D打印混凝土抗压强度预测模型可为评估不同打印参数下3D打印混凝土的抗压强度提供理论参考。     

二氧化钛陶瓷浆料的制备及其直写成型3D打印

直写成型技术是一种基于浆料挤出的3D打印技术,具有设备简单、投入低,可在温和条件下制备出精细复杂的三维结构的优点,在先进陶瓷制备领域潜力巨大。但直写成型技术目前面临材料缺乏、浆料制备困难等难题。为此,首先自主研发了一种基于气压式的新型直写成型3D打印机。在此基础上,以二氧化钛为原料,选用聚乙烯醇(PVA)作为流动助剂和粘结剂,制备了适用于直写成型的二氧化钛陶瓷浆料,研究了PVA含量对浆料流变行为及其直写成型可打印性的影响。在此基础上,打印加工了具有复杂形状和结构的二氧化钛制件,考察了其断面形貌、打印精度,并进一步分析了其烧结后的性能等。结果表明PVA的加入有效的降低浆料的黏度,提高其流动性,有助于其3D打印,改善了打印制件层与层之间的粘结情况,但PVA含量大于10wt%后,会导致浆料在沉积阶段出现坍塌现象。此外,PVA含量增加后,会导致烧结件硬度降低,收缩率增加。     

3D打印腰部健康护具设计研究

目的 通过对3D打印材料与技术的概述、腰部健康护具市场需求的分析,探索3D打印技术与传统医疗护具设计结合的可能性,思考个性与适应性、艺术与功能性、单价与制造速度的平衡与协调。方法 以腰部健康护具为研究切入点,借助SLS、SLA打印技术,重点关注可成型工艺(同一材料的3D打印设计改良),对增加造型可塑性以及更为概念性的设计方略层面进行研究。结果 基于使用、技术、个性三方面的需求,设计了具备磁疗功效和定制特点的3D打印腰部健康护具。经实验测试,佩戴性良好,各项指标达到了设计预期。结论 未来的3D打印发展方向,材料研究仍将是重点,除了材料的多元化、智慧化,技术的互动、增效也会进一步刷新人类社会的制造观念;有效利用3D打印技术的便捷性特点和可定制特点,势必成为未来“可定制化”无障碍产品设计重要的研发和探索方向。     

3D Printing of Ceramics with Controllable Green-Body Configuration Assisted by the Polyvinyl Alcohol-Based Physical Gels

Additive manufacturing of ceramics has received intense attention. In particular, 3D-printed ceramics with customized shapes are highly desirable in the chemical industry, aerospace, and biomedical engineering. Nevertheless, developing a simple and cost-effective process that shapes dense ceramics to complex geometries remains challenging because of the high hardness and low ductility of ceramic materials. Extrusion-based printing, such as direct ink writing (DIW), often requires supporting materials that pose additional difficulties during printing. Herein, a simple approach is developed to produce stretchable ceramic green bodies of zirconia and alumina for DIW. The ink is composed of polyvinyl alcohol (PVA) and an aqueous suspension of ceramic powders. Besides the colloidal network formed by the ceramic particles, PVA plays an important role in tuning the printability of the aqueous ink. Through a freeze-thaw process, PVA crystallizes to form physical networks. This strategy provides highly stretchable hydrogel green bodies that can be reprogrammed to complex geometries difficult for common DIW printing. The subsequent drying, debinding, and sintering processes produce ceramics with dense structures and fine mechanical properties. In short, this work demonstrates an efficient method for the DIW of ceramic parts that can be reprogrammed to complex geometries.     

3D printing of smart materials: A review on recent progresses in 4D printing

ABSTRACT

Additive manufacturing (AM), commonly known as three-dimensional (3D) printing or rapid prototyping, has been introduced since the late 1980s. Although a considerable amount of progress has been made in this field, there is still a lot of research work to be done in order to overcome the various challenges remained. Recently, one of the actively researched areas lies in the additive manufacturing of smart materials and structures. Smart materials are those materials that have the ability to change their shape or properties under the influence of external stimuli. With the introduction of smart materials, the AM-fabricated components are able to alter their shape or properties over time (the 4th dimension) as a response to the applied external stimuli. Hence, this gives rise to a new term called ‘4D printing’ to include the structural reconfiguration over time. In this paper, recent major progresses in 4D printing are reviewed, including 3D printing of enhanced smart nanocomposites, shape memory alloys, shape memory polymers, actuators for soft robotics, self-evolving structures, anti-counterfeiting system, active origami and controlled sequential folding, and some results from our ongoing research. In addition, some research activities on 4D bio-printing are included, followed by discussions on the challenges, applications, research directions and future trends of 4D printing.     

磁控触变流体的3D打印工艺研究

针对现有磁控智能流体无法应用于3D打印的问题,本文制备了一种在磁场调控下能够实现溶胶-凝胶可逆转变的新型磁控触变流体,并对其打印工艺进行了研究。采用全系统损耗润滑油、有机膨润土和Fe₃O₄颗粒制备了不同配比的打印样品,搭建了直写式3D打印实验平台,研究其可打印性。流变学实验表明:磁控触变流体有机膨润土含量越高,触变性越强,剪切变稀越明显;磁场强度越强,屈服应力越高,储存模量越高。3种挤出方式下的打印实验结果表明,采用匀料恢复挤出方式打印的结构具备最高分辨率和最大高度。磁控触变流体在根据其流变特性设计的挤出装置下具有良好可打印性,为该材料应用于柔性传感、软体机器人个性化复杂结构设计与驱动、微流控检测等领域奠定了基础。     

3D printing technology and its impact on Chinese manufacturing

For both developed and developing countries, manufacturing plays a crucial role in international competition. There is a growing consensus that 3D printing (3DP) technologies will revolutionise the development of global manufacturing. Although considerable research has previously been conducted to define the technological and economic benefits of 3DP on global manufacturing, minimal research has linked 3DP with Chinese manufacturing (CM). Therefore, to address this research gap and to investigate 3DP’s potential impact on alleviating CM’s development issues, this paper explores the definition, characteristics and mainstream technologies of 3DP, presents the current situation and the main problems of CM, and analyses the potential impact of 3DP on the development of CM. Then, this study introduces the current 3DP promotion and industrialisation situation in China as well as the issues with promoting 3DP in CM.     

3D Printing of Salt as a Template for Magnesium with Structured Porosity

Porosity is an essential feature in a wide range of applications that combine light weight with high surface area and tunable density. Porous materials can be easily prepared with a vast variety of chemistries using the salt‐leaching technique. However, this templating approach has so far been limited to the fabrication of structures with random porosity and relatively simple macroscopic shapes. Here, a technique is reported that combines the ease of salt leaching with the complex shaping possibilities given by additive manufacturing (AM). By tuning the composition of surfactant and solvent, the salt‐based paste is rheologically engineered and printed via direct ink writing into grid‐like structures displaying structured pores that span from the sub‐millimeter to the macroscopic scale. As a proof of concept, dried and sintered NaCl templates are infiltrated with magnesium (Mg), which is typically highly challenging to process by conventional AM techniques due to its highly oxidative nature and high vapor pressure. Mg scaffolds with well‐controlled, ordered porosity are obtained after salt removal. The tunable mechanical properties and the potential to be predictably bioresorbed by the human body make these Mg scaffolds attractive for biomedical implants and demonstrate the great potential of this additive technique.     

On the bottleneck of adopting 3D printing in manufacturing

A timely book, titled ‘Standards, Quality Control, and Measurement Sciences in 3D Printing and Additive Manufacturing’ has been published to discuss the bottleneck issues when adopting 3D printing in manufacturing. This book review provides some personal thoughts and discussions on the new book.