Deformation behavior of sub-micron and micron sized alumina particles in compression

Technical Report · Mon Sep 01 00:00:00 EDT 2014

DOI:https://doi.org/10.2172/1159119· OSTI ID:1159119

Sarobol, Pylin ^[1]; Hall, Aaron Christopher. ^[1]; Urrea, David A. ^[1]; Chandross, Michael E. ^[1]; Carroll, Jay D. ^[1]; Boyce, Brad L. ^[1]; Mook, William M. ^[1]; Kotula, Paul Gabriel ^[1]; McKenzie, Bonnie Beth ^[1]; Bufford, Daniel Charles ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

The ability to integrate ceramics with other materials has been limited due to high temperature (>800°C) ceramic processing. Recently, researchers demonstrated a novel process, aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub-micron sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, knowledge in fundamental mechanisms for ceramic particles to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this work, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub-micron sized ceramic particles; this is the first fundamental step needed to explain coating formation in the AD process. High purity, single crystal, alpha alumina particles with nominal sizes of 0.3 µm and 3.0 µm were examined. Particle characterization, using transmission electron microscopy (TEM), showed that the 0.3 µm particles were relatively defect-free single crystals whereas 3.0 µm particles were highly defective single crystals or particles contained low angle grain boundaries. Sub-micron sized Al₂O₃ particles exhibited ductile failure in compression. In situ compression experiments showed 0.3µm particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activity was observed within these particles during compression. These sub-micron sized Al₂O₃ particles exhibited large accumulated strain (2-3 times those of micron-sized particles) before first fracture. In agreement with the findings from experimentation, atomistic simulations of nano-Al₂O₃ particles showed dislocation slip and significant plastic deformation during compression. On the other hand, the micron sized Al₂O₃ particles exhibited brittle fracture in compression. In situ compression experiments showed 3µm Al₂O₃ particles fractured into pieces without observable plastic deformation in compression. Particle deformation behaviors will be used to inform Al₂O₃ coating deposition parameters and particle-particle bonding in the consolidated Al₂O₃ coatings.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1159119
• Report Number(s): SAND--2014-18127; 537749
• Country of Publication: United States
• Language: English