Chemical Supercritical Fluid Infiltration of Pyrocarbon with Thermal Gradients: Deposition Kinetics and Multiphysics Modeling

The chemical supercritical fluid infiltration process is a recent variation of the vapor (CVI) that allows rapid and efficient manufacturing ceramic-matrix composites (CMCs), albeit still needing optimization. This article proposes quantitative assessment dynamics through experiments modeling. kinetics carbon deposition were determined two sets experiments: CVD on single filament at pressures between 10 50 bar ranging 120 bar. CVI conducted under important thermal gradients interpreted using model-based reconstitution these gradients. We found (i) kinetic law has to incorporate potential effect reverse reaction (i.e., etching C by H2); (ii) activation energy pre-exponential factor both decrease with pressure up bar, then remain roughly constant, (iii) although apparent modest, favorable situation occurs in which an front builds travels from hottest coldest part preform due presence sufficient heat flux. A numerical simulation process, based solution momentum, heat, mass balance equations, fed appropriate laws for effective transfer properties porous medium their evolution progress, was performed validated comparing simulated actual profiles.