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

An integrated modelling approach of Chemical Vapour Infiltration of a fibro us preform by methyltrichlorosilane, featuring coupled reactor fluid mechan ics and porous medium gas transport has been developed. The coupling betwee n transport/reaction phenomena inside and outside the preform is rather str ong, both physically and numerically. An important counter-effect of the re active preform on the surrounding gas-phase composition is evidenced; also, an appreciable dissymmetry of the densification rate inside the preform, e ven with negligible convective transport inside it. Such an approach brings new informations for understanding the physico-chemical phenomena of CVI a nd new guidelines for preform densification optimisation.