| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
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| Symposium
|
Progress towards Understanding the Synthesis and Behavior of Metals Far from Equilibrium: A SMD Symposium Honoring Enrique Lavernia on the Occasion of His 60th Birthday
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| Presentation Title |
Compositional and Structural Evolution of Passivation Layers in Heat- and Humidity-treated Aluminum Powder for Cold Spray Applications |
| Author(s) |
Cameron Crook, Maryam Z. Azar, Diran Apelian, Daniel R. Mumm, Lorenzo Valdevit, Jasper Zebulon Lienhard, Christopher A Schuh |
| On-Site Speaker (Planned) |
Lorenzo Valdevit |
| Abstract Scope |
Cold spray is an advantageous thermal spray technology due to the low intrinsic temperatures, minimal oxidation, preservation of feedstock microstructural characteristics, and the availability of a broad assortment of sprayable materials. Empirical knowledge suggests that the passivation layer of powder feedstocks strongly affects the critical impact velocity of the particle, and in turn the optimal processing conditions and the resulting mechanical properties of the coating. However, no comprehensive studies been performed to directly correlate the characteristics (composition, thickness and structure/crystallinity) of the native grown oxide layer to the critical impact velocity. High-purity Aluminum powders were manufactured by gas atomization and subjected to various temperatures and humidity levels using a fluidized bed system. Here we demonstrate these powders exposed to high relative humidities result in significant evolution of the passivation layer. We show that these microstructural/morphological evolutions directly correlate with a substantial increase in critical impact velocity and we identify three possible mechanisms responsible for the change through a combination of materials techniques, including XPS, FTIR, HR-TEM/STEM, and single particle impacts. |
| Proceedings Inclusion? |
Undecided |