| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | January 23, 2014 |
| Latest Amendment Date: | August 14, 2019 |
| Award Number: | 1351705 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Siddiq Qidwai
sqidwai@nsf.gov (703)292-2211 CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | July 1, 2014 |
| End Date: | June 30, 2020 (Estimated) |
| Total Intended Award Amount: | $400,000.00 |
| Total Awarded Amount to Date: | $487,994.00 |
| Funds Obligated to Date: |
FY 2018 = $8,000.00 FY 2019 = $79,994.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
926 DALNEY ST NW ATLANTA GA US 30318-6395 (404)894-4819 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
GA US 30332-0420 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Mechanics of Materials and Str, Special Initiatives |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT 01001920DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
The objective of this Faculty Early Career Development (CAREER) Program grant is to uncover physical mechanisms governing the mechanical properties of nanoporous materials for hierarchical structures where struts and joints are complex. Nanoporous metals can be thought of as a three-dimensional interconnected network of struts and joints with typical size in the range 10-100 nm. These materials possess high surface-to-volume ratios, electrical conductivity, catalytic activity, and strength. They have shown great promise in many applications, for example as high-performance catalysts or electrodes for fuel cells and batteries. The ability to design nanoporous metals with enhanced mechanical properties is crucial for all applications, yet fundamental understanding of how their internal structure influences macroscopic properties is still lacking, especially for hierarchical structures where struts and joints are themselves complex (e.g. are nanocrystalline). This project aims to uncover physical mechanisms governing the mechanical properties of such structures. This will be achieved through a comprehensive experimental campaign utilizing in-situ deformation experiments across different scales. The effects of the nanoporous metal geometrical structure will be investigated with the aid of analytical and numerical models, as well as by conducting experiments on scaled-up structures.
The project will generate crucial insights into the deformation mechanisms governing mechanical properties of hierarchical nanoporous metals, thus providing a basic scientific knowledge necessary for controlling and optimizing their properties and bringing closer wider adaptation of this class of materials. Research activities are closely integrated with education and outreach efforts: both graduate and undergraduate students will work on the project, thus gaining cutting-edge skills and expertise in nanotechnology and science; the PI will work with high school teachers and students in the Atlanta area through Georgia Intern Fellowship for Teachers program and through Georgia Tech's Women in Engineering summer camps; some of the results will be introduced in engineering courses at Georgia Tech as case studies; the PI will participate in Tech to Teaching program that inspires students to choose a teaching career.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This project examined the cause behind exceptional mechanical properties (strength, stiffness, etc.) of nanoporous (NP) metals. NP metals are porous sponges with pores and solid elements (ligaments) at the nanoscale. If one imagines a sponge as a multistory building with highly disordered support columns, then the columns (ligaments) of this structure are made out of 50 or so atoms in thickness on average. More curiously, the ligaments themselves can have even smaller structure such as nanosized grains or twins. Preliminary experiments showed that NP metals with hierarchical ligaments can have very high strength and stiffness but the cause for these exceptional properties was mostly attributed to the nanoscale size of the components. This project focused on understanding how mechanical properties of hierarchical NP metals are affected by geometry and internal microstructure.
To achieve this NP metals with nanotwins and nanograins (Pt, Cu) were synthesized and their properties were obtained using nanoindentation and micropillar compression experiments. In addition, 3D printing was used to fabricate large scale replicas of NP metals and test them in the large scale. This provided a benchmark for the contribution of geometrical structure on the properties and allowed decoupling of the nanoscale contribution. Along with collaborators, a much more nuanced enhancement in properties was revealed that stems from both the geometry and the nanoscale hierarchical structure of NP metals.
Throughout the duration of the project, different possible applications of NP metals were explored. For example, nanoporous (NP) Copper was synthesized with tailorable properties so as to mimic dentin's morphology and mechanical strength and stiffness. This correspondence in properties may allow use of NP metals to advance tooth restoration techniques by using them as model systems to study infiltration of dentin with resins. Moreover, the multi-scale porosity of NP metals, was leveraged in the synthesis of columnar nanoporous platinum with superior activity for butadiene hydrogenation when compared on the basis of the catalyst mass. Finally, NP Copper structure, mechanical and electrical properties before and after heat treatment make this an ideal candidate for next generation interconnects.
In terms of broader impacts, this project contributed to supporting graduate students in completing highly specialized degrees. Educational aspects of this project were disseminated through undergraduate and graduate classwork at Georgia Institute of Technology. The project contributed a module in a middle school summer camp for girls organized by the Women in Engineering program. The project was a catalyst for the development of NCorr, an open source 2D Digital Image Correlation (DIC) software that allows for tracking of deformation at different scales. NCorr has contributed to scientific advancements in multiple areas and has helped train next generation practicioners across the world.
Last Modified: 05/29/2024
Modified by: Antonia Antoniou
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