Three‐Dimensional Printing of Multifunctional Nanocomposites: Manufacturing Techniques and Applications

The integration of nanotechnology into three‐dimensional printing (3DP) offers huge potential and opportunities for the manufacturing of 3D engineered materials exhibiting optimized properties and multifunctionality. The literature relating to different 3DP techniques used to fabricate 3D structures at the macro‐ and microscale made of nanocomposite materials is reviewed here. The current state‐of‐the‐art fabrication methods, their main characteristics (e.g., resolutions, advantages, limitations), the process parameters, and materials requirements are discussed. A comprehensive review is carried out on the use of metal‐ and carbon‐based nanomaterials incorporated into polymers or hydrogels for the manufacturing of 3D structures, mostly at the microscale, using different 3D‐printing techniques. Several methods, including but not limited to micro‐stereolithography, extrusion‐based direct‐write technologies, inkjet‐printing techniques, and popular powder‐bed technology, are discussed. Various examples of 3D nanocomposite macro‐ and microstructures manufactured using different 3D‐printing technologies for a wide range of domains such as microelectromechanical systems (MEMS), lab‐on‐a‐chip, microfluidics, engineered materials and composites, microelectronics, tissue engineering, and biosystems are reviewed. Parallel advances on materials and techniques are still required in order to employ the full potential of 3D printing of multifunctional nanocomposites.     

3D成型SiO_2/PVA水凝胶支架的摩擦行为

利用3D成型技术,通过先成型后冷冻交联2步法制备不同孔隙率的SiO_2/聚乙烯醇(PVA)水凝胶支架,研究了SiO_2/PVA水凝胶支架的重复摩擦行为,分析了SiO_2/PVA水凝胶支架的摩擦原理。结果表明:SiO_2/PVA水凝胶支架能够保持三维贯通的立体结构,最大孔隙率可达42.3%。低摩擦速率(10-6~10-3 m/s)下,SiO_2/PVA水凝胶支架摩擦力稍高于块体SiO_2/PVA水凝胶,且随孔隙率的提高而稍有降低;而高摩擦速率(10-2~1m/s)下,SiO_2/PVA水凝胶支架和块体SiO_2/PVA水凝胶的摩擦力相近,孔隙率对支架摩擦力影响不明显。低正压力载荷(0.3kPa)下,SiO_2/PVA水凝胶支架重复摩擦性优于块体SiO_2/PVA水凝胶,这与支架结构能保持稳定的水润滑层相关。     

美国WiTricity公司无线充电领域专利分析

为了了解一直致力于研发无线充电技术的美国重要创新型公司——WiTricity公司的核心技术的研发情况,通过专利计量的方法对该公司的专利申请情况进行详细分析。利用美国USPTO的数据,根据专利申请数量、专利申请类型、技术领域分布、技术合作、专利发明人等指标研究了WiTricity公司的专利布局和申请策略。总体来看,目前WiTricity公司仍然处在技术研发的快速增长阶段,公司的整体研发实力较强。     

生物医用材料的3D打印技术与发展

近年来,由于3D打印技术的迅猛发展,有关3D打印技术的应用受到科学界广泛关注,特别是生物医学领域。3D打印材料的瓶颈制约着3D打印技术的发展,特别是用于生物医学领域的打印材料,只有非常局限的几种,但是研究可打印生物医用材料意义重大,经济效益显著。简述了3D打印技术在生物医学工程上的应用。重点综述了用于3D打印的生物医用材料,主要涉及金属、陶瓷、高聚物、复合材料以及生物墨水等,并且阐述了3D打印材料的发展前景。     

粉末钛合金3D打印技术研究进展

粉末钛合金3D打印技术以低成本、易成形、柔性化制备、零件性能优异等优势,近年来成为钛合金近净成形制造领域的研究热点。总结了国内外粉末钛合金3D打印技术的研究进展,包括激光熔化沉积成形技术(LMD)、激光选区熔化成形技术(SLM)、电子束选区熔化成形技术(SEBM)。比较研究了3种成形技术制备的钛合金的组织特点及力学性能,并讨论了粉末钛合金3D打印技术的市场化现状与未来发展趋势。     

Performance evaluation of ProJet multi-material jetting 3D printer

The purpose of this paper is to quantitatively evaluate the performance of a multi-material jetting 3D printer, ProJet 5500X, especially the capability for micro manufacturing. Unlike other single material 3D printer, ProJet 5500X uses photopolymers as the build material and wax as the support material. The building performance was evaluated by building a modified version of the standard benchmark model with a high-resolution printing mode. The dimensional error, forming quality and surface roughness of the printed parts have been measured and analysed using a microscope, a 3D coordinate measuring machine and a surface profilometer. Using wax as the support material, fine features as small as 0.25?mm, lateral features and sharper edges could all be properly built, despite the rough side surfaces observed in the printed part. Identical features (3?mm pins) were precisely built with an accuracy of 15?µm. The research provides first-hand detailed performance knowledge in the ProJet system for understanding the working principle and comparison with other 3D printing systems.     

Modelling and characterisation for the responsive performance of CF/PLA and CF/PEEK smart materials fabricated by 4D printing

4D printing, which is the combination of 3D printing technology and printable smart materials, provides the potential of automating actuation devices. In this paper, we have used a modified-fused deposition modelling 3D printing technology to fabricate a double-layer laminate smart material, which can be activated by temperature directly or by an electric circuit indirectly. A double-layer laminate mathematical model has been developed to describe the bending behaviour caused by the mismatch strain between the surface layer and the basal layer. The electrocaloric deformation testings were performed to find the different bending rules of this low-cost printed active composite in different physical states. The considerable maximal deformation values and deformation force (7?mm and 100?mN for these carbon fibre (CF)/polylactic acid specimens, and 10?mm and 200?mN for these CF/polyether-ether-ketone specimens in the paper) provide this double-layer smart material and 4D printing method the prospective to be applied in biomimetic sensors, actuators, transducers, and artificial muscles.     

EIGA法制备激光3D打印用TA15钛合金粉末

采用电极感应熔炼气雾化(EIGA)法制备了激光3D打印用TA15钛合金粉末,研究了熔炼功率对粉末收得率、粒径分布、粉末形貌、松装密度和流动性等特征的影响。结果表明,随着感应熔炼功率增大,粉末收得率和平均粒径减小,当熔炼功率为65kW时,粉末收得率超过62%,中值粒径D_(50)小于100μm,松装密度为2.731g/cm3,流动性为22.46s/50g。对粒径50~180μm的粉末采用激光3D打印,激光直接沉积成形的TA15钛合金样品表面无宏观裂纹和气孔等缺陷,金相组织为细晶网篮组织,制备的TA15钛合金粉末具有良好的可打印性。     

甘油增韧淀粉/PLA易降解打印耗材的制备

采用甘油与PLA粉末在无水乙醇中预混合,80℃烘干后再加入淀粉进行双螺杆熔融共混,制备出淀粉含量为20%的甘油增韧淀粉/PLA复合材料。扫描电镜和拉曼光谱分析结果表明,采用该方法可使淀粉在PLA基体中均匀分布。力学性能测试显示,PLA拉伸强度、断裂延展率和弯曲强度均随淀粉含量增加而降低,但甘油含量为8%时淀粉/PLA复合材料的韧性明显提升。以甘油增韧的淀粉/PLA复合材料制成易降解FDM打印耗材,实际3D打印效果良好。     

Experimental Study on Tunable Electromagnetic Shielding by Microlattice Materials with Organized Microstructures

Porous metal materials are widely used for preventing electromagnetic interference, control of heat conduction and impact absorbing. However, a limitation associated with porous metals is that their irregular and non‐uniformal microstructures make their functions non‐desirably tunable. In this report, the authors propose a microlattice material with precisely controlled microstructures for electromagnetic (EM) shielding. An effective medium model taking into account of the EM stimulated surface current of the metal wires is developed to characterize the EM shielding effect of the microlattice metal. In addition, a compact and integrated measuring device is constructed by using a 3D printing method for experimental verification. The theoretical predictions agree well with the experimental measurement. The influence of the geometrical parameters of the microlattice metals on EM shielding effect is also studied. The theoretical model and the compact measuring system provide robust and efficient tools for the design of EM shielding materials.