Effect of the Alumina Shell on the Melting Temperature Depression for Aluminum Nanoparticles

dc.contributor.author Rivero, Iris
dc.contributor.author Pantoya, Michelle
dc.contributor.author Chauhan, Garima
dc.contributor.author Levitas, Valery
dc.contributor.department Aerospace Engineering
dc.date 2018-02-13T18:16:14.000
dc.date.accessioned 2020-06-29T22:45:55Z
dc.date.available 2020-06-29T22:45:55Z
dc.date.copyright Thu Jan 01 00:00:00 UTC 2009
dc.date.embargo 2013-11-26
dc.date.issued 2009-08-13
dc.description.abstract <p>The dependence of aluminum (Al) melting temperature on particle size was studied using a differential scanning calorimeter and thermogravitmetric analyzer for particles encapsulated in an oxide shell. Pressure generation within the Al core leads to an increase in melting temperature in comparison with traditional melting temperature depression calculated using the Gibbs−Thomson equation. On the basis of elasticity theory, the pressure in the Al core at the onset of melting is caused mainly by surface tension at the alumina−air and Al−alumina interfaces. This implies that pressure due to the difference in thermal expansion of aluminum and alumina relaxes. A possible relaxation mechanism is discussed. The static strength of the alumina shell and the maximum static generated pressure in aluminum were evaluated. Mechanically damaging the oxide shell was shown to reduce the melting temperature due to a decrease in generated pressure within the Al core. Thus, reduction in melting temperature can be used as a quantitative measure of damage to the oxide shell. Results from X-ray diffraction studies show that 17-nm diameter Al particles had a 2-nm thick alumina shell in the γ-phase, while for a flat surface Al had an amorphous alumina shell stable to a thickness of 4 nm. Thus, pressure due to surface tension promotes denser γ-phases. Since particles with shells initially in the amorphous or γ-phase show the same flame speed and ignition delay time, fast oxidation observed under high heating rates cannot be explained by a phase transformation in the alumina shell. These findings have important implications for the melt-dispersion mechanism for fast Al oxidation.</p>
dc.description.comments <p>Posted with permission from <em>Journal of Physical Chemistry C</em> 113 (2009): 14088–14096, doi:<a href="http://dx.doi.org/10.1021/jp902317m" target="_blank">10.1021/jp902317m</a>. Copyright 2009 American Chemical Society.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/aere_pubs/38/
dc.identifier.articleid 1037
dc.identifier.contextkey 4856623
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath aere_pubs/38
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/2037
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/aere_pubs/38/2009_LevitasVI_EffectAluminaShell.pdf|||Fri Jan 14 23:51:44 UTC 2022
dc.source.uri 10.1021/jp902317m
dc.subject.disciplines Aerospace Engineering
dc.subject.disciplines Industrial Engineering
dc.subject.disciplines Materials Science and Engineering
dc.subject.disciplines Mechanical Engineering
dc.subject.disciplines Metallurgy
dc.subject.keywords Mechanical Engineering
dc.subject.keywords Materials Science and Engineering
dc.title Effect of the Alumina Shell on the Melting Temperature Depression for Aluminum Nanoparticles
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication 450e4508-4d15-482a-8403-ebc773a5d639
relation.isAuthorOfPublication 850871e3-115a-428e-82cc-cbfafef5cf66
relation.isOrgUnitOfPublication 047b23ca-7bd7-4194-b084-c4181d33d95d
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