Low-cost Manufacturing of Bioinspired Damage-Tolerant Ceramic Composites

尽管陶瓷-金属复合材料具有良好的性能，但由于加工成本和挑战，它们迄今尚未投入商业应用。传统的制备层状陶瓷-金属复合材料的方法是将金属相熔融渗透到陶瓷支架的缝隙中。缝隙越小，渗透越困难。由于大多数金属和陶瓷之间的润湿性很差，该过程需要高压和温度来将熔化的金属挤压到陶瓷相的缝隙中。该项目旨在开发受自然启发的制造策略，以实现陶瓷-金属复合材料的低成本制造。天然材料，如骨头和贝壳的珍珠层部分，已经开发出结构复合材料，使用一组相当普通的成分，这些成分表现出非凡的机械性能。例如，贝壳将易碎的陶瓷材料转化为超韧性材料(珍珠层)，方法是在分层的砖和砂浆中加入约5%的聚合物。微观结构。科学界在确定生物结构复合材料的设计原则方面非常成功。然而，制造业知识差距依然存在。这些挑战包括陶瓷砖之间的小间隙渗透的挑战，获得延展性(同时坚固)砂浆的挑战，适当的(金属-陶瓷)界面设计的挑战，以及高昂的成本。金属和陶瓷复合材料的低成本制造工艺可以显著增加其在汽车、航空航天、石油和国防等各个行业的应用，并在高性能耐磨部件、刀具、轻质结构复合材料和航空发动机部件等产品中得到应用。出于这些原因，该项目直接影响到美国的经济福利和国家安全。该项目的教育目标是通过NanoExplorer增加纳米技术-STEM的多样性。针对高中生的暑期计划，特别强调女学生，包括拉丁裔学生。这项研究的目标是研究陶瓷复合材料用于损伤容限结构应用的加工和制造的基本机理。该项目的重点是通过脉冲电沉积了解纳米孪晶金属在三维多孔陶瓷支架的纳米间隙(100 Nm)中的渗透情况。保守估计表明，该工艺的能耗比传统的熔融金属渗透工艺低200多倍。与熔融金属相比，电沉积中的液态电解液的粘度要小得多，因此可以有效地渗透到陶瓷砖之间的微小缝隙中。一类无法在强度和韧性之间权衡的金属是？纳米孪晶？金属。纳米孪晶金属具有高密度的共格孪晶界，这已被证明提高了强度和延展性。脉冲电沉积是制备纳米孪晶金属的主要方法之一。为了解决金属-陶瓷界面的挑战，计划在陶瓷砖上化学沉积一层薄的金属层，这将导致均匀的涂层，以及陶瓷和金属之间的强大附着力。这项研究如果成功，将在以下主题中产生新的基础知识：(I)通过脉冲电沉积直接合成层状陶瓷支架的纳米孪晶金属的生长机制和微观结构；(Ii)纳米通道(100 Nm)中脉冲电沉积过程的动力学；以及(Iii)通过电沉积渗透纳米多孔陶瓷支架。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Despite favorable properties of ceramic-metal composites, they have not been applied commercially to date, due in large part to processing cost and challenges. The conventional method for manufacturing lamellar ceramic-metal composites is melt-infiltration of the metal phase into the gaps of the ceramic scaffold. The smaller the gap, the more difficult the infiltration. Because of the poor wetting between most metals and ceramics, the process requires high pressure and temperature to squeeze the molten metal into the gaps in the ceramic phase. This project aims at developing manufacturing strategies inspired by nature to enable low-cost fabrication of ceramic-metal composites. Natural materials such as bone and the nacreous part of sea-shells have developed structural composites, using a set of rather ordinary constituents, which exhibit extraordinary mechanical properties. For example, seashells convert a brittle ceramic material to a super-tough material (nacre) by incorporation of around 5% polymer, in a layered ?brick-and-mortar? microstructure. The scientific community has been very successful in identifying the design principles of biological structural composites. However, manufacturing knowledge gaps persist. These include the challenge of infiltration of small gaps between ceramic bricks, the challenge of obtaining ductile (while strong) mortars; the challenge in design of proper (metal-ceramic) interfaces; and the high cost. Low-cost processes for fabrication of metal−ceramic composites can substantially increase their applications in various industries including automotive, aerospace, oil and defense, in products such as high performance wear-resistance parts, cutting tools, lightweight structural composites, and aero-engine components. For these reasons, the project directly impacts American economic welfare and national security. The educational objective of the project is focused on increasing the diversity in nanotechnology- STEM through ?NanoExplorer? summer program for high school students, with particular emphasis on female students, including Latinos. The goal of this research is to investigate the mechanisms underlying processing and manufacturing of ceramic composites for damage-tolerant structural applications. The project is focused on understanding infiltration of nanotwinned metals into nano-gaps (100 nm) of a 3-dimensional porous ceramic scaffold by pulsed electrodeposition. A conservative estimate shows that the energy consumption in this process is more than 200-fold smaller than the conventional molten metal infiltration process. The liquid electrolyte in electrodeposition has much less viscosity compared to molten metals, and hence can effectively penetrate into the small gaps between the ceramic bricks. A class of metals that defeat the trade-off between strength and toughness are ?nanotwinned? metals. Nanotwinned metals have high density of coherent twin boundaries, which has been shown to enhance both strength and ductility. Pulsed electrodeposition is one of the primary methods of synthesis of nanotwinned metals. To address the metal-ceramic interface challenge, electroless deposition of a thin metal layer on ceramic bricks is planned, which will result in uniform coating, as well as strong adhesion between ceramics and metals. This research, if successful, will result in new fundamental knowledge in following subjects: (i) Growth mechanism and microstructure of nanotwinned metals directly synthesized by pulsed electrodeposition into a laminated ceramic scaffold; (ii) Kinetics of pulsed electrodeposition process in nano-channels (100 nm); and (iii) Infiltration of a nano-porous ceramic scaffold by electrodeposition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.