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Surface Melting of Particles: Predicting Spherule Size in Vapor-Phase Nanometer Particle Formation1
Published online by Cambridge University Press: 10 February 2011
Abstract
There is still no reliable method to predict the all-important size of the ‘primary’ spherules found in combustion-synthesized particulate products. Toward this end, we introduce surface melting concepts in developing a coagulation-coalescence model for nanoparticles in the low temperature regions of diffusion flames. The associated surface self-diffusivity, which controls the rate of spherule sintering at temperatures well below the equilibrium melting point, is therefore modified to include an important size effect. This formulation is used to calculate the sintering rate of two adjacent particles in a flame coagulation environment corresponding to a condensed phase volume fraction of Ca. 10−1 ppm. Predicted spherule sizes show encouraging agreement with our experimental data for ca. 10 nm diameter Al2O3 particles synthesized on the fuel side of a laminar CH4/O2 diffusion flame seeded with Al(CH3)3 (TMA)[1].
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- Research Article
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- Copyright
- Copyright © Materials Research Society 1997
Footnotes
Graduate Research Assistant, PhD program.
Prof. ChE; Director, Yale HTCRE Lab.; Email: [email protected]
Paper #V5.36, MRS Fall Meeting, 1996 Boston, MA USA.
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