Fabrication of Short-Fibre Reinforced SiCN by Injection Moulding of Pre-Ceramic Polymers

Pre-ceramic polymers were used as organic vehicle in this study forming a ceramic matrix after pyrolysis. Carbon short-fibres were chosen as fibre materials. Because of inadequate processing properties of the used pre-ceramic polymer, blending with thermoplastic waxes and process additives was necessary. An amorphous Si–C–N network was obtained as the matrix of the short-fibre composite after pyrolysis of the polysilazane precursor. In this study, the influence of different fibre types, fractions and lengths on compounding and moulding has been analysed. Torque measurements were used for characterising the flow ability and the thermal stability of the feedstock. Simulation of injection moulding processes was used as tool for predicting the form filling of test moulds as well as for supporting future development and moulds construction. In fibre-reinforced parts, the fibre distribution and alignment affect the mechanical properties. With injection moulding simulation, the fibre alignment can be predicted and arranged. This offers the chance for smart comprehensive design of parts and moulds to match the mechanical requirements. The resulting composite parts have been analysed regarding their microstructure and mechanical properties.