INFILTRATION AND COATING OF THE POROUS CARBONACEOUS BODIES BY CHEMICAL VAPOR-DEPOSITION

In this article, an empirical modelisation of infiltration and of simultaneous infiltration and coating of the porous carbonaceous substrates by chemical vapour deposition is presented. The problem was stated concentrating on the neccessity of distinguishing the pores filling from pores closing, and trying to avoid the mechanisms of the gas-phase reactions. The set of equations describing the stated problem was formulated and applied to different types of substrates and different deposits. The obtained results showed that the infiltration and coating of the porous substrates can be described by the formulated set of equations, and that they can be used for estimation of the relevant kinetics parameter values. Moreover, these values can be used for prediction of the evolution of some properties of the obtained material (e.g., densities, density-porosity relationship) as a function of deposition time. The calculated values showed good agreement with the experimental ones. The estimation of the values of rate constants enabled the explanation of the behaviour of closed porosity formation, deposition within the pores, and coating of the substrates for different systems.