Continuous coating of ceramic fibres by industrial-scale laser driven CVD: fibre modification and structure of interfaces

A laser induced chemical vapour deposition process (L-CVD) has been developed to treat and coat ceramic fibre bundles. This method is characterised by several advantages, among them high deposition rates and very short residence times of the fibres in the deposition chamber. Laser irradiation of SiC based fibres has been found to result in strong structural changes due to recrystallisation accompanied by evolving gaseous SiO and CO. The deposition of thin py-C layers shifts this thermal SiC fibre degradation process to significantly higher power densities, which results in coated fibres without degradation. With CH4 as precursor, layers of highly ordered pyrolytic graphite have been deposited on Nicalon fibres.