Effect of polymorphic phase transformations in alumina layer on ignition of aluminium particles

Document Type

Article

Publication Date

8-1-2006

Abstract

The mechanism of aluminium oxidation is quantified and a simplified ignition model is developed. The model describes ignition of an aluminium particle inserted in a hot oxygenated gas environment: a scenario similar to the particle ignition in a reflected shock in a shock tube experiment. The model treats heterogeneous oxidation as an exothermic process leading to ignition. The ignition is assumed to occur when the particle's temperature exceeds the alumina melting point. The model analyses processes of simultaneous growth and phase transformations in the oxide scale. Kinetic parameters for both direct oxidative growth and phase transformations are determined from thermal analysis. Additional assumptions about oxidation rates are made to account for discontinuities produced in the oxide scale as a result of increase in its density caused by the polymorphic phase changes. The model predicts that particles of different sizes ignite at different environment temperatures. Generally, finer particles ignite at lower temperatures. The model consistently interprets a wide range of the previously published experimental data describing aluminium ignition.

Identifier

33747147390 (Scopus)

Publication Title

Combustion Theory and Modelling

External Full Text Location

https://doi.org/10.1080/13647830600578506

e-ISSN

17413559

ISSN

13647830

First Page

603

Last Page

623

Issue

4

Volume

10

Grant

DAAE30-03-D-1015

Fund Ref

Office of Naval Research

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