直写成型制备多孔陶瓷技术研究进展

多孔陶瓷具有耐高温、可控孔结构、高孔隙率、化学稳定性和生物惰性等特点，是应用于支柱、生物、催化和电气等领域的理想材料。传统多孔陶瓷的制造方法主要有颗粒堆积、添加造孔剂、发泡、溶胶-凝胶等。近年来，随着增材制造技术的发展，直写成型技术因其简单的设备构造和良好的浆料兼容性，被广泛应用于制造复杂结构和图案的多孔陶瓷。本文综述了直写成型多孔陶瓷的技术方法及其在各领域的应用，详细分析了直写成型技术制备多孔陶瓷材料的优劣势，提出了直写成型制备多孔陶瓷所面临的挑战，并对直写成型制备多孔陶瓷技术发展趋势进行了展望。     

多孔陶瓷的直写成型工艺研究进展

多孔陶瓷内部含有大量三维孔隙,具有轻质、高强、高比表面积、低导热系数等特性,但是多孔陶瓷的传统制备工艺对结构和性能的可控性较低,很难满足先进能源、航空航天、电子信息等领域的发展对多功能高性能材料的需求。直写成型工艺是一种制造成本低、材料使用性广、技术可拓展性高的3D打印工艺,不仅可以直接制备具有轻量化特点的多孔陶瓷,而且结合其他工艺可以实现多孔陶瓷的层级结构和多功能化,有望实现设计与制造、材料与器件、结构与功能的一体化。介绍了直写成型法3D打印多孔陶瓷的工艺原理,综述了直写成型法直接制备多孔陶瓷、直写成型结合乳液/泡沫法和冷冻干燥法制备层级多孔陶瓷的研究进展。由于工艺柔性高,直写成型法能够与其他方法良好融合,以制备具有特殊结构和性能的多孔材料,尤其是兼顾高强度、高孔隙率和形状可控性的层级多孔陶瓷。最后,总结了目前直写成型工艺制备多孔陶瓷的优势和不足,并对打印材料性能、打印设备和主要应用领域的发展进行了展望。     

典型双马来酰亚胺树脂固化动力学模型的研究

对由二苯甲烷双马来酰亚胺与二烯丙基双酚A体系制得的典型双马来酰亚胺树脂体系的固化动力学模型进行研究,目前国内绝大多数双马来酰亚胺树脂体系都是在此基础上改性得到的。并采用DSC方法研究典型双马来酰亚胺树脂的固化过程,用恒温和动态两种方法分析其固化反应。根据自催化与n级反应方程,采用least-squares方法和Kissinger方法进行数据处理,建立该树脂体系的固化动力学模型并确定其固化动力学参数,此模型与实验结果具有良好的吻合性。同时该模型揭示了典型双马来酰亚胺树脂体系的固化反应是按不同机理分段进行的,在反应过程中由自催化模型转变为n级反应模型。此模型为合理的研究双马来酰亚胺树脂体系的工艺参数,保证产品质量以及工艺优化提供了必要的前提条件。      

树脂基复合材料原位固化制造技术概述

随着树脂基复合材料应用领域的扩大和使用量的增加,发展树脂基复合材料自动化、低成本制造技术成为先进制造技术领域的研究热点.本文详细介绍了树脂基复合材料原位固化制造技术的概念、产生与意义,对目前国内外各种树脂基复合材料原位固化制造技术的研究作了综述；对比分析了用γ射线、X射线、热、微波、紫外光和电子束等固化方式进行原位固化...     

用于环氧树脂固化监测的自参考型光纤固化传感器

研究了一种新型的自参考型光纤固化传感器,用于环氧树脂固化过程的实时监测。用光纤芯折射率为1.558的多模光纤制成端面反射型折射率传感器,利用环氧树脂的折射率与固化度之间的对应关系,通过实时测量环氧树脂的折射率进行固化监测。在固化过程中,当环氧树脂的折射率变化到与光纤芯的折射率相等时,传感界面的反射信号为零,传感器可对零点偏置和灵敏系数进行校准,在此后的固化过程中,传感器能够定量地测量环氧树脂的固化度。在用多个传感器对树脂内不同部位的固化过程同时进行监测的场合,各传感器经实时自参考校准后,可根据各自的灵敏系数对输出信号统一定标,从而可以相互比较,实时地反映不同部位的固化反应过程之间的差异。      

自动铺放工艺制备罐外固化复合材料的力学行为

针对碳纤维增强树脂基复合材料IM7/CYCOM5230-1罐外固化预浸料,研究了自动铺放（AFP）罐外固化（OOA）预浸料的制备过程并优化了铺放工艺参数,采用热分析手段研究了CYCOM5230-1树脂固化动力学及黏度特性,在此基础上开发了一种短时固化工艺,并评价了基于此工艺制备的OOA复合材料力学性能。结果表明,AFP铺放过程中预浸料间缝隙会影响OOA复合材料的成型质量,采用铺放压力为180 N、加热温度为50℃、铺放速率为0.20 m/s的铺放参数,可获得表面平整、成型质量优异的复合材料样件。热分析结果表明,罐外固化CYCOM5230-1树脂室温黏度大,满足OOA工艺中真空压实排气需求。短时固化工艺可达到与典型固化工艺相同水平固化度,提升了固化效率,且制备的复合材料可以达到59%的纤维体积分数及低于0.5%的孔隙率,其力学性能与典型固化工艺制备的复合材料相当,并且能够达到热压罐复合材料的水平。     

自组装法制备聚苯乙烯光子晶体的研究进展

系统介绍了自组装法制备聚苯乙烯光子晶体的研究进展,综述了重力沉降、垂直沉降、电泳沉积、离心沉积、涂覆沉积和界面沉积等自组装方法的优缺点以及国内外研究的新进展;分析了微球粒径、悬浮液浓度、温度、湿度和压强等因素对组装效果的影响;阐述了自组装法制备聚苯乙烯光子晶体的发展趋势.     

典型建筑外窗窗型隔声性能验证

为验证现存典型建筑外窗窗型的隔声性能,对天津市7条典型交通线路沿线的交通噪声进行现场监测和分析,得到交通噪声声压级及噪声频谱特性,在此基础上选取天津市现有的7种典型的建筑外窗窗型,对其隔声性能进行现场测试。对比分析所测试不同外窗窗型的实际隔声效果。研究结果显示,在天津7条典型道路或铁路噪声影响下,只有推拉塑钢单层玻璃双层窗、平开断桥铝中空玻璃窗2两种窗型能够完全满足居住建筑室内声环境的要求。研究结果可应用于道路和铁路交通沿线新建或既有建筑的交通噪声环境评价,改变以往评价中仅依据外窗厂家提供的隔声量数值的评价方式,提高评价的准确性。     

等温DSC法研究RFI用环氧树脂固化动力学

为了预测固化反应的进程,采用STA 449C型差示扫描量热仪,用等温DSC法研究了室温下成膜、中温固化的RFI工艺用(E-44/E-21(6/4,质量比))/GA-327＝100/40(质量比)环氧树脂体系在80、90、100、110、120℃下的固化过程,通过Matlab数据拟合良好性统计法得到了n级固化模型、自催化模型及复合模型方程中的各个参数值。根据R2和离差平方和SSE确定了适合的动力学模型。研究表明:该树脂体系的固化反应具有自催化和扩散控制的特征,低温下受扩散控制的影响更大;该体系的固化反应动力学符合自催化反应动力学模型,其表观活化能E_a为56.7kJ/mol,指前因子A为1.18×107 s-1,固化反应的反应级数m、n分别为0.529和1.561。      

相变微胶囊悬浮液的对流换热特性研究进展

相变微胶囊悬浮液是既具有流动性又兼具蓄热能力的功能性流体。相变微胶囊悬浮液在工作过程中涉及复杂的流体流动与传热以及储热过程,近年来成为国内外学者研究的热点。对相变微胶囊悬浮液在圆管、小(微)通道内的对流换热特性进行了综述,重点阐述了国内外学者对于相变微胶囊悬浮液是否能强化对流换热存在的分歧,并提出了自己的分析与看法。分析了圆管与小(微)通道对流换热机理的区别,最后概述了强化相变微胶囊悬浮液对流换热的方法。     

墨水直写、喷墨打印和激光直写技术及其在微电子器件中的应用

直写技术是一种新型微加工技术,其加工过程不需模板并可在亚微米至厘米范围实现材料加工成型。墨水直写、喷墨打印和激光直写作为最常用的直写技术,具有强大的二维、三维成型能力和优异的成型精度,可实现金属、陶瓷、聚合物、水凝胶等复杂构型的程序化构筑,被广泛应用于微电子、组织工程、微流控等领域。阐述了这3种直写技术的构型原理和材料选择,重点介绍了其在微电子器件制造中的应用,讨论了当前研究的难点和热点问题,并对其未来发展趋势进行了展望。     

墨水直写、喷墨打印和激光直写技术及其在微电子器件中的应用

直写技术是一种新型微加工技术,其加工过程不需模板并可在亚微米至厘米范围实现材料加工成型.墨水直写、喷墨打印和激光直写作为最常用的直写技术,具有强大的二维、三维成型能力和优异的成型精度,可实现金属、陶瓷、聚合物、水凝胶等复杂构型的程序化构筑,被广泛应用于微电子、组织工程、微流控等领域.阐述了这3种直写技术的构型原理和材料选择,重点介绍了其在微电子器件制造中的应用,讨论了当前研究的难点和热点问题,并对其未来发展趋势进行了展望.     

3D Printing by Multiphase Silicone/Water Capillary Inks

3D printing of polymers is accomplished easily with thermoplastics as the extruded hot melt solidifies rapidly during the printing process. Printing with liquid polymer precursors is more challenging due to their longer curing times. One curable liquid polymer of specific interest is polydimethylsiloxane (PDMS). This study demonstrates a new efficient technique for 3D printing with PDMS by using a capillary suspension ink containing PDMS in the form of both precured microbeads and uncured liquid precursor, dispersed in water as continuous medium. The PDMS microbeads are held together in thixotropic granular paste by capillary attraction induced by the liquid precursor. These capillary suspensions possess high storage moduli and yield stresses that are needed for direct ink writing. They could be 3D printed and cured both in air and under water. The resulting PDMS structures are remarkably elastic, flexible, and extensible. As the ink is made of porous, biocompatible silicone that can be printed directly inside aqueous medium, it can be used in 3D printed biomedical products, or in applications such as direct printing of bioscaffolds on live tissue. This study demonstrates a number of examples using the high softness, elasticity, and resilience of these 3D printed structures.     

Large‐Scale Direct‐Writing of Aligned Nanofibers for Flexible Electronics

Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well‐patterned microstructures in flexible electronics. Electro‐hydrodynamic (EHD) direct‐writing technology enables large‐scale deposition of highly aligned nanofibers in an additive, noncontact, real‐time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground‐breaking research progress in the field of EHD direct‐writing technology is summarized, including a brief chronology of EHD direct‐writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct‐written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics.     

羧甲基纤维素对多壁碳纳米管导电墨水性能的影响

传统中性墨水多用丙烯酸树脂做增稠剂,且不具备导电能力,因此将羧甲基纤维素(CMC)与多壁碳纳米管(MWCNT)混合,使制备墨水书写后具备导电能力。采用超声制得CMC-MWCNT导电墨水,通过中性笔书写于纸上,对制备导电墨水的稳定性能、流变性能、书写性能和书写字迹的耐腐蚀性能、导电性能、折叠稳定性能进行分析,并与市场上晨光中性笔墨水(CG)进行对比。当添加CMC为0.3wt%、0.6wt%时,导电墨水的Zeta电位、屈服应力、屈服黏度均较低,书写时出现漏墨,书写后电阻较小,但折叠一百次后电阻增大较多,分别增大32.3%、17.9%。当添加CMC为0.9wt%、1.2wt%、1.5wt%时,导电墨水的Zeta电位绝对值均大于30 mV,体系处于稳定态;屈服应力与屈服黏度随CMC添加量增大而增大;CMC为0.9wt%和1.2wt%的导电墨水书写正常,书写后电阻分别为14.9 kΩ/cm、15.6 kΩ/cm,折叠100次后电阻分别增大8.7%、7.8%;1.5wt%CMC的导电墨水书写时有断墨,书写后电阻为28.3 kΩ/cm,折叠100次后电阻增大9.5%。与CG相比,1.2wt%CMC的导电墨水具有相似的稳定性能、流变性能、书写性能,并具备导电能力,可点亮LED灯。      

Hybrid 3D Printing of Soft Electronics

Hybrid 3D printing is a new method for producing soft electronics that combines direct ink writing of conductive and dielectric elastomeric materials with automated pick‐and‐place of surface mount electronic components within an integrated additive manufacturing platform. Using this approach, insulating matrix and conductive electrode inks are directly printed in specific layouts. Passive and active electrical components are then integrated to produce the desired electronic circuitry by using an empty nozzle (in vacuum‐on mode) to pick up individual components, place them onto the substrate, and then deposit them (in vacuum‐off mode) in the desired location. The components are then interconnected via printed conductive traces to yield soft electronic devices that may find potential application in wearable electronics, soft robotics, and biomedical devices.     

石膏的直写成型：可打印石膏浆料的研制

石膏是雕像、建筑和铸造模具(合金和陶瓷)的常用材料。采用直写成型(Direct Ink Writing, DIW)打印石膏可避免其他3D打印技术(如Binder Jetting, PBBJ等)中存在水化反应不充分等问题, 获得高强度3D打印石膏。为了延缓水化反应获得充足的打印操作时间, 本研究通过添加缓凝剂和增稠剂, 研制了一种适用于直写成型的石膏浆料, 并打印了多种石膏三维结构(如蜘蛛网和木材堆积结构等)。结果表明, 质量分数为0.6%柠檬酸(Citric Acid, CA)的缓凝效果最好, 极大地减少了石膏流动性的经时损失。质量分数为0.3%羟丙基甲基纤维素(Hydroxypropyl Methylcellulose, HPMC)的增稠效果最好, 使石膏浆料具有良好的打印性能。CA的选择性吸附使得石膏晶体定向生长, 延长水化反应时间, 但一定程度降低石膏强度。HPMC加速石膏浆料中絮凝结构形成, 导致其粘度和剪切弹性模量升高。直写成型3D石膏件的抗压强度约为20 MPa, 远高于PBBJ等方法制备的石膏件的抗压强度。     

Direct-ink writing 3D printed energy storage devices: From material selectivity,design and optimization strategies to diverse applications

Additive manufacturing, also known as three-dimensional (3D) printing technology, has recently emerged as a promising fabrication technology for a variety of applications with diverse complex architectures, as it allows for simple printing of desired pattern, fast prototyping, reduced fabrication process and low cost. As an important type of 3D printing technology, direct ink writing (DIW) endows the electrochemical energy storage devices (EESDs) with excellent electrochemical performance with high areal energy density and excellent rate capability owing to enhanced ion/electron transportation and surface kinetics induced by the designed patterns and device architecture. In view of the current infancy and urgency, as well as the lack of in-depth discussion, we critically overview the DIW 3D printing technology for EESDs devices in terms of materials selectivity principle for ink formulation and rheology, technical challenges (design principles and optimization strategies) and various EESDs applications in a comprehensive yet concise fashion. In this review, firstly, we introduce the typical features of DIW 3D printing technology. Subsequently, we discuss the design and optimization strategies towards several key parameters of DIW, including printable ink formulation, printing process and post treatment, device configuration and electrode pattern, porosity and tortuosity, as well as the package. Thereafter, we summarize the advances and recent progress of various EESDs devices fabricated by DIW technology, including conventional lithium/sodium ion batteries, newly emerged lithium sulfur/selenide/oxygen batteries, lithium/sodium-metal batteries, Ni-Fe batteries, zinc-air batteries, zinc ion batteries and supercapacitors, with a detailed analysis of rational design mechanism of each EESD. At last, the remaining challenges and research orientations in this booming field are proposed to motivate the future research and development of 3D printed EESDs.     

Molecular imaging of banknote and questioned document using solvent-free gold nanoparticle-assisted laser desorption/ionization imaging mass spectrometry

Direct chemical analysis and molecular imaging of questioned documents in a non/minimal-destructive manner is important in forensic science. Here, we demonstrate that solvent-free gold-nanoparticle-assisted laser desorption/ionization mass spectrometry is a sensitive and minimal destructive method for direct detection and imaging of ink and visible and/or fluorescent dyes printed on banknotes or written on questioned documents. Argon ion sputtering of a gold foil allows homogeneous coating of a thin layer of gold nanoparticles on banknotes and checks in a dry state without delocalizing spatial distributions of the analytes. Upon N(2) laser irradiation of the gold nanoparticle-coated banknotes or checks, abundant ions are desorbed and detected. Recording the spatial distributions of the ions can reveal the molecular images of visible and fluorescent ink printed on banknotes and determine the printing order of different ink which may be useful in differentiating real banknotes from fakes. The method can also be applied to identify forged parts in questioned documents, such as number/writing alteration on a check, by tracing different writing patterns that come from different pens.     

基于笔法模型的国画干笔飞白模拟

为实现国画技法干笔飞白效果的计算机模拟,提出了在笔法模型的基础上,将飞白效果类型分为丝状和斑块状进行模拟,其中包括墨量的递减,飞白区域的判定和笔迹的生成几个部分。通过对笔锋模型的含墨量检测,在墨量不足的区域作笔触分岔的效应,并在父笔道的基础上,叠加若干个具有相同模型的子笔道,实现“干笔飞白”效果的模拟。