High-temperature ceramic matrix composites prepared via microwave energy enhanced chemical vapour infiltration

Porter, Matthew Thomas ORCID: 0000-0002-9227-4185 (2020). High-temperature ceramic matrix composites prepared via microwave energy enhanced chemical vapour infiltration. University of Birmingham. Ph.D.

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Abstract

SiC fibre reinforced SiC composites must be >90% dense in order to offer a superior structural material alternative to current systems used in aerospace engines. To achieve this the use of microwave energy enhanced chemical vapour infiltration (MCVI) has been investigated as a possible faster and more energy efficient manufacturing route. Key processing parameters were identified and their effects on the rate of deposition of SiC and the composite’s microstructure were assessed using a suite of characterisation techniques. The rate of SiC deposition had an Arrhenius relationship with the temperature and the use of microwaves is thought to have also lowered the activation energy of the decomposition reaction. The fundamental benefit of this advanced processing method was the inverse thermal gradient produced by using microwave energy. This was studied both experimentally and via finite-difference time-domain modelling (FDTD). The latter showed a direct correlation between susceptor size and microwave absorption. A SiC slurry calendaring impregnation route was also developed to fill macro porosity in the SiC fibre preform. A number of slurries were characterised to find a suitable slurry composition that reduced the total volume of porosity in the preform to further reduce CVI processing time.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):