INFLUENCE OF THE ANNEALING PROCESS PARAMETERS IN THE PRODUCTION OF NEW SHORT-FIBRE-REINFORCED C/C-SIC COMPOSITES

摘要

A new short-fibre-reinforced C/C-SiC composite was developed by using the liquid silicon infiltration (LSI) process, which consists of three processing steps. A carbon-fibre-reinforced plastic (CFRP) composite was fabricated. The shaping of this composite was realised by a thermoset injection moulding process. The CFRP composite was converted into a porous C/C composite by pyrolysis. Liquid silicon was infiltrated to form a dense C/C-SiC composite. An additional heat treatment (annealing process) of the cured CFRP composite completes the cross-Unking of the polymer and thus a higher carbon yield was achieved. In addition, the microstructure (open and closed porosity, crack network) along the whole process route was strongly influenced. In this paper, the influence of the annealing parameters is discussed. The starting materials (carbon fibre, polymer, curing agent and lubricant) as well as the microstructures of the composites (cured CFRP, annealed CFRP, C/C and C/C-SIC composites) were characterised. These investigations showed a direct relationship between the used parameters of annealing process and the degree of cure as well as the formation of porosity. In regards to the optimisation of the process an optimal process condition was specified.