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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

Y. Xing
Affiliation:
Department of Chemical Engineering, High Temperature Chemical Reaction Engineering Lab., Yale University, New Haven, CT 06520–8286, USA
D. E. Rosner
Affiliation:
Department of Chemical Engineering, High Temperature Chemical Reaction Engineering Lab., Yale University, New Haven, CT 06520–8286, USA
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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].

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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Footnotes

2

Graduate Research Assistant, PhD program.

3

Prof. ChE; Director, Yale HTCRE Lab.; Email: rosner@htcre.eng.yale.edu

1

Paper #V5.36, MRS Fall Meeting, 1996 Boston, MA USA.

References

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