Interaction between a reactive preform and the surrounding gas-phase during CVI

Abstract
An integrated modelling approach of Chemical Vapour Infiltration of a fibrous preform by methyltrichlorosilane, featuring coupled reactor fluid mechanics and porous medium gas transport has been developed. The coupling between transport/reaction phenomena inside and outside the preform is rather strong, both physically and numerically. An important counter-effect of the reactive preform on the surrounding gas-phase composition is evidenced ; also, an appreciable dissymmetry of the densification rate inside the preform, even with negligible convective transport inside it. Such an approach brings new informations for understanding the physico-chemical phenomena of CVI and new guidelines for preform densification optimisation.