The application of repro-modelling to pyrocarbon CVD/CVI homogeneous mechanisms for various hydrocarbons precursors

The pyrocarbon Chemical Vapor Infiltration (CVI) is a widespread process for the production of high-performance composite materials with applications in aerospace and braking technology. Several hundred species and thousands of elementary reactions may be required to describe comprehensively the gas-phase pyrolysis that occurs prior to pyrocarbon deposition. The repro-modelling technique is a well suited reduction method of such a large chemical reaction mechanism. Chemical kinetics are described as explicit functional relations between the source terms and the concentrations of related species, obtained by fitting the numerical solution of differential equations. The reduction procedure consists in a parameterization based on orthonormal polynomials. This technique has been applied to zero and one-dimensional simulations of a global model for pyrolysis of methane, propane and propylene. These simulations were performed in different conditions of pressure, temperature and residence time of the precursor. The approximations of species concentration profiles are in good agreement with the original numerical data and with experimental data, thus providing a new insight in the understanding of pyrocarbon deposition.