Preparation of SiCN ceramic fibres via UV irradiation curing polysilazane

The amorphous polymer-derived SiCN ceramic fibres were fabricated successfully with homemade polysilazane (PSZ) through a series of processes, including melt-spinning, UV curing and pyrolyzing at 1100°C in the N₂ atmosphere. The effects of UV irradiation time on the composition, microstructure and ceramic yields of PSZ fibres were investigated by relevant characterizations, including gel permeation chromatography, Fourier transforms infrared spectroscopy, scanning electron microscopy, X-ray diffraction and thermal gravimetric analysis, respectively. The UV cross- linking reaction occurred on the surface layer of the PSZ fibres, where the UV radiations were expected to play a critical role in accelerating the cleavage of Si-H, N-H and C-H bonds to form the cross-linked networks of Si-O-Si, Si-N-Si and Si-C-Si. The PSZ fibres remained fibrous on UV irradiation for up to 8 h. The PSZ fibres irradiated for 20 h revealed an optimum ceramic yield value of 80.6%, which is higher than the unirradiated by 40.3%. The reported UV irradiation provides a novel curing method for the fabrication of SiCN ceramic fibres using PSZ fibres. (author)