Structure and Low-temperature Tribology of Lubricious Nanocrystalline ZnO/Al2O3 Nanolaminates and ZrO2 Monofilms Grown by Atomic Layer Deposition

Description:

Currently available solid lubricants only perform well under a limited range of environmental conditions. Unlike them, oxides are thermodynamically stable and relatively inert over a broad range of temperatures and environments. However, conventional oxides are brittle at normal temperatures; exhibiting significant plasticity only at high temperatures (>0.5Tmelting). This prevents oxides' use in tribological applications at low temperatures. If oxides can be made lubricious at low temperatures, they would be excellent solid lubricants for a wide range of conditions. Atomic layer deposition (ALD) is a growth technique capable of depositing highly uniform and conformal films in challenging applications that have buried surfaces and high-aspect-ratio features such as microelectromechanical (MEMS) devices where the need for robust solid lubricants is sometimes necessary. This dissertation investigates the surface and subsurface characteristics of ALD-grown ZnO/Al2O3 nanolaminates and ZrO2 monofilms before and after sliding at room temperature. Significant enhancement in friction and wear performance was observed for some films. HRSEM/FIB, HRTEM and ancillary techniques (i.e. SAED, EELS) were used to determine the mechanisms responsible for this enhancement. Contributory characteristics and energy dissipation modes were identified that promote low-temperature lubricity in both material systems.

Creator(s): Romanes, Maia Castillo
Creation Date: December 2008
Partner(s):
UNT Libraries
Collection(s):
UNT Theses and Dissertations
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Total Uses: 734
Past 30 days: 37
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Creator (Author):
Publisher Info:
Publisher Name: University of North Texas
Place of Publication: Denton, Texas
Date(s):
  • Creation: December 2008
  • Digitized: August 31, 2009
Description:

Currently available solid lubricants only perform well under a limited range of environmental conditions. Unlike them, oxides are thermodynamically stable and relatively inert over a broad range of temperatures and environments. However, conventional oxides are brittle at normal temperatures; exhibiting significant plasticity only at high temperatures (>0.5Tmelting). This prevents oxides' use in tribological applications at low temperatures. If oxides can be made lubricious at low temperatures, they would be excellent solid lubricants for a wide range of conditions. Atomic layer deposition (ALD) is a growth technique capable of depositing highly uniform and conformal films in challenging applications that have buried surfaces and high-aspect-ratio features such as microelectromechanical (MEMS) devices where the need for robust solid lubricants is sometimes necessary. This dissertation investigates the surface and subsurface characteristics of ALD-grown ZnO/Al2O3 nanolaminates and ZrO2 monofilms before and after sliding at room temperature. Significant enhancement in friction and wear performance was observed for some films. HRSEM/FIB, HRTEM and ancillary techniques (i.e. SAED, EELS) were used to determine the mechanisms responsible for this enhancement. Contributory characteristics and energy dissipation modes were identified that promote low-temperature lubricity in both material systems.

Degree:
Level: Doctoral
Language(s):
Subject(s):
Keyword(s): ZnO | nanocrystalline | oxide ceramics | atomic layer deposition | solid lubricant | nanolaminate | ZrO2
Contributor(s):
Partner:
UNT Libraries
Collection:
UNT Theses and Dissertations
Identifier:
  • OCLC: 441319547 |
  • ARK: ark:/67531/metadc9741
Resource Type: Thesis or Dissertation
Format: Text
Rights:
Access: Public
License: Copyright
Holder: Romanes, Maia Castillo
Statement: Copyright is held by the author, unless otherwise noted. All rights reserved.