How is it possible to get optimal infiltration fronts during chemical vapor infiltration with thermal gradients ?

Abstract

Introducing thermal gradients to improve the Chemical Vapor Infiltration (CVI) process is a key strategy to overcome its principal drawback, namely, the presence of residual porosity in the central part of ceramic composite material preforms.The aim is to create an infiltration front starting from the least accessible part of the porous preform and progressing towards its surface. However, in practice, it may be quite difficult to evaluate the magnitude of the thermal gradient necessary for the achievement of this desired infiltration front. Modeling may bring solutions for the design of a successful processing situation. This paper reviews four distinct application examples, for which multi-physics numerical modeling studies have been developed and validated. These cases are also examined using analytical computations of a front infiltration criterion in order to discuss the influence of processing parameters on the quality of the process and of the resulting material.

Keywords

• Chemical vapor infiltration
• Process modeling
• Ceramic-matrix composites