Baker, Andrew
(2024)
Insights into Nanoscale Adhesion via in situ Transmission Electron Microscopy.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Surface adhesion governs the performance of material interfaces, from large-scale applications such as the energy loss in an automobile engine to small-scale applications such as the stability of nanoparticles. At the nanometer length scale, there are many aspects of adhesion that are not well understood due to the inherent challenges in experimental investigations at the nanoscale. An emerging technique for investigating nanoscale adhesion is performing nanoscale contact-and-separation tests inside of a transmission electron microscope, coupling force and displacement information with high-resolution measurements of material composition, structure, and morphology. In the present work, this technique was leveraged to advance the fundamental understanding of nanoscale adhesion.
Surface adhesion governs the performance of material interfaces, from large-scale applications such as the energy loss in an automobile engine to small-scale applications such as the stability of nanoparticles. At the nanometer length scale, there are many aspects of adhesion that are not well understood due to the inherent challenges in experimental investigations at the nanoscale. An emerging technique for investigating nanoscale adhesion is performing nanoscale contact-and-separation tests inside of a transmission electron microscope, coupling force and displacement information with high-resolution measurements of material composition, structure, and morphology. In the present work, this technique was leveraged to advance the fundamental understanding of nanoscale adhesion.
There are three primary contributions from this work. First, we addressed the open question of how nanoscale adhesion changes with applied load in hard, technologically relevant materials. We showed that nanoscale adhesion was governed primarily by strength-limited separation (also called “pop-off”), rather than by crack-like separation (aka “peel off”) as previously believed. Here adhesion experiments of nanoscale contacts demonstrated the need for a paradigm shift from traditional contact mechanics models in interpreting nanoscale adhesion data. Second, we utilized insight from previous nanoscale adhesion experiments to measure the adhesion of noble-metal nanoparticles to oxide support. In these technologically relevant material systems, interfacial adhesion (through the established relationship between adhesion and nanoparticle sintering) governs the efficiency and lifetime of nanoparticles in applications such as chemical synthesis, energy generation, and biosensors. We tested six different metal/oxide systems, and validated the accuracy of our technique by matching materials trends in adhesion from prior literature. Third, once the accuracy of our technique was established, we expanded the scope of the investigation to the adhesion between bimetallic nanoparticles and oxide supports, looking specifically at how adhesion depends on nanoparticle surface composition. The results showed adhesion varies non-monotonically with surface composition which is attributed to the modification of adhesive bonding via intra-particle charge transfer between dissimilar metals. Finally, current and future work is presented, where adhesion experiments were performed for additional systems beyond the scope of current techniques to further develop the understanding of how nanoparticles adhere to their supports.
Share
| Citation/Export: |
|
| Social Networking: |
|
Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
3 June 2024 |
| Date Type: |
Publication |
| Defense Date: |
18 March 2024 |
| Approval Date: |
3 June 2024 |
| Submission Date: |
1 March 2024 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
136 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering and Materials Science |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Adhesion, Nanoparticles, TEM |
| Date Deposited: |
03 Jun 2024 14:41 |
| Last Modified: |
03 Jun 2024 14:41 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45832 |
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[img]](https://d-scholarship.pitt.edu/style/images/fileicons/application_pdf.png)
![[feed]](/images/feed-icon-32x32.png){kind=icon}