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Dynamic convection-driven thermal gradient chemical vapor infiltration

Published online by Cambridge University Press:  31 January 2011

John Y. Ofori  and
Stratis V. Sotirchos
John Y. Ofori
Affiliation:
Department of Chemical Engineering, University of Rochester, Rochester, New York 14627
Stratis V. Sotirchos*
Affiliation:
Department of Chemical Engineering, University of Rochester, Rochester, New York 14627
*
a) Author to whom correspondence should be addressed.
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Abstract

The operation of the process of chemical vapor infiltration using a combination of pressure pulsing and thermal gradients is theoretically investigated in this study. Past studies had shown that pulsing of the pressure in the gas phase can lead to a dramatic reduction of the density gradients in the densifying structure, in comparison to those seen in isobaric diffusion-driven Pinfiltration, with significant gradients present only in the vicinity of the external surface of the preforms. Using a detailed model for chemical vapor infiltration under unsteady nonisothermal conditions, we show that temperature gradients, created in our study through microwave heating, can, in conjunction with pressure pulsing, eliminate the density gradients in the final product. Moreover, appropriate tuning of the operational parameters can lead to a situation where densification proceeds from the interior of the preform toward the external surface.

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Journal of Materials Research , Volume 11 , Issue 10 , October 1996 , pp. 2541 - 2555
Copyright
Copyright © Materials Research Society 1996

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