Ask a Librarian

Threre are lots of ways to contact a librarian. Choose what works best for you.

HOURS TODAY

11:00 am - 3:00 pm

Reference Desk

CONTACT US BY PHONE

(802) 656-2022

Voice

(802) 503-1703

Text

MAKE AN APPOINTMENT OR EMAIL A QUESTION

Schedule an Appointment

Meet with a librarian or subject specialist for in-depth help.

Email a Librarian

Submit a question for reply by e-mail.

WANT TO TALK TO SOMEONE RIGHT AWAY?

Library Hours for Friday, March 29th

All of the hours for today can be found below. We look forward to seeing you in the library.
HOURS TODAY
8:00 am - 6:00 pm
MAIN LIBRARY

SEE ALL LIBRARY HOURS
WITHIN HOWE LIBRARY

MapsM-Th by appointment, email govdocs@uvm.edu

Media Services8:00 am - 4:30 pm

Reference Desk11:00 am - 3:00 pm

OTHER DEPARTMENTS

Special Collections10:00 am - 5:00 pm

Dana Health Sciences Library7:30 am - 6:00 pm

 

CATQuest

Search the UVM Libraries' collections

UVM Theses and Dissertations

Browse by Department
Format:
Print
Author:
Stevenson, Kevin D.
Dept./Program:
Mechanical Engineering
Year:
2006
Degree:
MS
Abstract:
Micro-Electro-Mechanical Systems (MEMS) have enabled miniaturized, cutting-edge technologies in the aerospace, transportation, biomedical engineering, and communications industries. A critical issue lies in the reliability of MEMS materials in response to thermomechanical stresses and their ability to combine high tensile strength and ductility simultaneously. Those criteria are not met with typical semiconducting materials such as silicon, but can be overcome using novel nanostructured materials, such as nanocrystalline metal thin films. A key characteristic of nanocrystalline materials is the ability to tailor mechanical strength by varying the average grain size. Metals with nanoscale grain structure have been produced showing superior, unique properties such as high strength and flow stress and superplasticity at very low temperatures. However, the dense grain boundary network associated with nanocrystalline materials results in a breakdown of the classical deformation mechanisms. This size-dependent effect is not fully understood. Further advanced mechanical testing is required to gain a comprehensive understanding of the grain size evolution during deformation. This thesis will present (1) the development of an electrochemical technique for the synthesis of Ni nanostructures and (2) the surface characterization and mechanical properties of these materials at the nanoscale.
The surface structure of electrplated Ni films was investigated to determine the ideal electrochemical environment to produce grain sizes between 10-80 nm. Pulsed-current deposition and organic additives were critical for obtaining grain sizes less than 30 nm. Standard AFM cantilevers (tip radius ~10 nm) were found to be insufficient for imaging grains smaller than 30 nm. However, high-resolution AFM cantilevers (tip radius ~1 nm) enabled accurate surface and grain analysis over the range of produced sizes. This non-destructive appraoch provided additional insight into the structure-property relationship of thin films at the nanoscale. An X-ray diffraction study verified the accuracy of average grain sizes calculated via AFM. Initial microhardness testing also provided insight into the mechanical properties of the deposited nickel.