Continuous coating of ceramic fibres by industrial-scale laser driven CVD. Process characterization

For high temperature applications of the fibre reinforced ceramic composites, the adhesion and chemical reactions at the fibre-matrix interface have to be engineered by coating the fibres. Based on an 6 kW cw-CO2 laser, an atmospheric pressure laser CVD process has been established which performs a continuous high rate coating of fibre bundles with ceramic layers. Reactor design and its optimisation is supported by computational fluid dynamics techniques. The gas flow dynamics, concentration of species, and heat transfer in the reaction chamber have been calculated. The reactor is equipped with an FTIR extraction system to control gas phase chemistry and with other diagnostic tools to control the process in operation. Uniform layers of ordered py-C are deposited onto C fibres and SiC fibres. FTIR results on the deposition of SiC on C fibres are given.