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Fragmentation and film growth in supersonic nanoaggregate aerosol deposition
Author(s) -
Ghosh Souvik,
Chen Xiaoshuang,
Li Chenxi,
Olson Bernard A.,
Hogan Christopher J.
Publication year - 2020
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16874
Subject(s) - coating , aerosol , supersonic speed , fragmentation (computing) , deposition (geology) , materials science , nozzle , chemical engineering , chemistry , chemical physics , analytical chemistry (journal) , nanotechnology , organic chemistry , paleontology , physics , sediment , biology , computer science , engineering , thermodynamics , operating system
Aerosol deposition with gas phase‐synthesized chain‐like nanoaggregates can yield dense coatings from the impaction of particles on a substrate; however, dense coating formation is not well understood. Here, we study coating consolidation at the single nanoaggregate level. Flame spray pyrolysis‐made tin oxide nanoaggregates are mobility (size) filtered, accelerated through a de Laval nozzle, and impacted on alumina substrates. TEM images obtained from low velocity collection and supersonic deposition are compared via quantitative image analysis, which reveals that upon supersonic impact nanoaggregates fragment into smaller aggregates. This suggests that fragmentation is a key step in producing coatings denser than the depositing nanoaggregates themselves. We supplement experiments with detailed particle trajectory calculations, which show that the impact energies per atom during nanoaggregate deposition are below 0.2 eV/molecule. These results suggest that fragmentation can only occur at locations where nanoaggregates bonded by van der Waals and capillary interactions.