CAREER: Bio-inspired Manufacturing of High Strength, High Toughness Metal-Graphene Composites

这项学院早期职业发展(Career)补助金专注于制造具有高强度和高韧性的仿生金属-石墨烯复合材料的研究。金属基复合材料由于重量轻、强度高，在汽车、航空航天、电子封装和热管理等领域得到了越来越广泛的应用。同时达到高强度和高韧性是许多结构应用的基本要求。然而，对金属基复合材料来说，两者兼而有之是一个巨大的挑战。自然进化的、耐损坏的材料，如珍珠岩、骨和木材，由于其分层复合结构，既坚固又坚韧。与具有复杂微结构的骨和木材不同，珍珠层具有简单的复合微结构，具有优异的机械性能。珍珠岩的韧性比其主要成分文石高三个数量级，这是因为它具有层次化的“砖瓦和砂浆”微结构。该项目研究了一种新的制造技术，以设计珍珠层或生物启发的三维金属-石墨烯复合材料。这项研究开发了计算和实验能力，以了解这些材料的强化和增韧机制。该项目对金属基复合材料行业产生了重大影响。这项研究得到了一个教育和推广计划的补充，该计划涉及课程开发、研究培训和吸引K-12学生和普通公众的参与。这项研究的目标是制造下一代、损伤容限的金属基复合材料，用于关键任务应用。研究计划是为了了解三维金属-石墨烯复合材料中“砖-砂浆”微结构的演变随制造工艺参数的变化。这种“砖瓦”结构的制造过程包括：将包覆蔗糖的铜片组装成三维结构，通过化学气相沉积(CVD)将蔗糖转化为石墨烯网络，然后通过热压将组装件固结为复合材料。本项目的目的是研究应变硬化、形变孪生、裂纹偏转和裂纹桥联的强韧化机制与“砖和砂浆”组织的函数，即铜片的直径和厚度，以及连续石墨烯薄膜的厚度。通过分子动力学模拟和力学测试对增强和增韧机理的基本理解指导了珍珠层激发的金属-石墨烯复合结构的制造。工艺、组织和性能之间的相互关系为金属基制造工艺的合理设计奠定了基础。这种仿生复合材料制造技术可以推广到其他金属-石墨烯复合材料，例如，使用铝、镁、镍、钛及其合金作为金属基质。该项目允许PI推进计算建模和金属基复合材料方面的知识库，并奠定了他在先进制造领域的长期职业生涯。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。

This Faculty Early Career Development (CAREER) grant focuses on research in the manufacturing of bio-inspired metal-graphene composites that have both high strength and high toughness. Due to their light weight and high strength, metal matrix composites are increasingly used in automotive, aerospace, electronics packaging and thermal management applications. Attaining both high strength and high toughness is an essential requirement for many structural applications. However, it is a significant challenge for metal matrix composites to have both. Nature-evolved, damage-tolerant materials such as nacre, bone and wood are both strong and tough because of their hierarchical composite structure. Unlike bone and wood, which have complex microstructures, nacre exhibits superior mechanical properties with a simple composite microstructure. The toughness of nacre is three orders of magnitude higher than that of its main constituent aragonite owing to its hierarchical “brick-and-mortar” microstructure. This project investigates a novel manufacturing technique to engineer nacre- or bio-inspired three-dimensional metal-graphene composites. This research develops computational and experimental capabilities to understand the strengthening and toughening mechanisms in these materials. This project greatly impacts the metal matrix composites industry. The research is complemented by an educational and outreach program involving curriculum development, research training and engaging K-12 students and the general public. The goal of this research is to manufacture next-generation, damage-tolerant metal matrix composites for mission-critical applications. The research plan is to understand the evolution of the “brick-and-mortar” microstructure in three-dimensional metal-graphene composites as a function of manufacturing process parameters. The fabrication of the “brick-and-mortar” structure involves assembling sucrose-coated copper platelets in a three-dimensional structure, converting sucrose into a graphene network by chemical vapor deposition (CVD) and consolidating the assembly by hot pressing into a composite. An objective of this project is to study the strengthening and toughening mechanisms of strain hardening, deformation twinning, crack deflection and crack bridging as functions of the “brick-and-mortar” microstructure, i.e., copper platelet diameter and thickness, and thickness of the continuous graphene film. The fundamental understanding of the strengthening and toughening mechanisms through molecular dynamics simulations and mechanical testing guides the manufacture of nacre-inspired metal-graphene composite structures. The correlation between processing, microstructure and properties establishes the rational design of the metal-matrix manufacturing process. The bio-inspired composite manufacturing technique can be extended to other metal-graphene composites, e.g., using aluminum, magnesium, nickel, titanium, and their alloys as metal matrices. This project allows the PI to advance the knowledge base in computational modeling and metal matrix composites and establishes his long-term career in advanced manufacturing.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.