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

这项教师早期职业发展（Career）资助的重点是研究制造具有高强度和高韧性的仿生金属-石墨烯复合材料。由于其重量轻，强度高，金属基复合材料越来越多地用于汽车，航空航天，电子封装和热管理应用。获得高强度和高韧性是许多结构应用的基本要求。然而，对于金属基复合材料来说，两者兼而有之是一个重大挑战。自然进化的耐损伤材料，如珍珠、骨头和木材，由于其分层复合结构，既坚固又坚韧。与具有复杂微观结构的骨和木材不同，珠质具有简单的复合微观结构，具有优越的机械性能。珍珠石的韧性比其主要成分文石的韧性高3个数量级，这是由于其分层的“砖瓦”结构。本项目研究了一种新的制造技术来设计真珠质或仿生三维金属-石墨烯复合材料。本研究发展了计算和实验能力，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。这项研究由一个教育和推广计划补充，包括课程开发，研究培训和参与K-12学生和公众。这项研究的目标是为关键任务应用制造下一代耐损伤金属基复合材料。研究计划是了解三维金属-石墨烯复合材料中“砖瓦”微观结构的演变与制造工艺参数的关系。“砖瓦”结构的制造包括将蔗糖涂层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，并通过热压将组装巩固成复合材料。本项目的目的是研究应变硬化、变形孪晶、裂纹挠曲和裂纹桥接的强化和增韧机制随“砖瓦”微观结构（即铜板直径和厚度）以及连续石墨烯薄膜厚度的变化。通过分子动力学模拟和力学测试对强化和增韧机制的基本理解指导了纳米材料激发金属-石墨烯复合结构的制造。加工过程、显微组织和性能之间的相关性为合理设计金属基制造工艺奠定了基础。这种仿生复合材料制造技术可以扩展到其他金属-石墨烯复合材料，例如，使用铝、镁、镍、钛及其合金作为金属基体。该项目使PI能够提升计算建模和金属基复合材料的知识库，并为他在先进制造业的长期职业生涯奠定基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.