Improved densification of SiCf/SiC composites by microwave-assisted chemical vapor infiltration process based on multifrequency solid-state sources excitation

This paper addresses the possibility of improving and controlling the temperature profile of a Ceramic Matrix Composite preform in a multiport Microwave-assisted Chemical Vapor Infiltration (MW-CVI) pilot-scale plant, based on a multifrequency excitation of the reactor by three solid-state sources. The choice of the most suited excitation frequencies is guided by rigorous numerical modeling of the reactor loaded by the sample, solving the coupled electromagnetic and thermal problems in a self-consistent way. The resulting infiltration front and residual porosity have been evaluated by a pseudo1D model, along the sample thickness, according to the previously computed heating pattern. The practical implementation and validation of the proposed technique are illustrated with MW-CVI trials on 10x10x0.3 cm3 SiCf/(SiC/BN)3/SiC preforms manufactured by Filament Winding method. The obtained results confirm the inside-out densification pattern, expected from the sample volumetric heating, along with an extension of the densification region by a factor of 2-3.