A cost effective route for the densification of carbon–carbon composites

Carbon–carbon (C/C) composites are candidate materials for many high temperature structural applications, but the high costs of manufacture prohibit their application in many cases, where the properties are desired but economically not affordable. This study focuses on the catalytic effects of metal carbonyl additions on the cross-linking efficiency of pre-ceramic silicon polymers, which are used for a rapid and cost effective densification of porous C/C composites. Whereas, the open pores in the C/C matrix, obtained via the polymer pyrolysis, are effectively closed by a one shot infiltration/pyrolysis step applying a dicobaltoctacarbonyl [Co2(CO)8] modified polysilane, a similar level of densification of porous C/C composites by a one time infiltration/pyrolysis of polycarbosilane could not be achieved, although catalytic additions of Co2(CO)8 were used as well. Besides the successful densification of C/C composites using the modified polysilane, improvement in the oxidation behaviour of the composites at elevated temperatures was also recorded. The influence of certain manufacturing process variables, such as curing temperature of the carbon precursor before pyrolysis and heat-treatment temperatures of the manufactured C/C composites before densification, on the structures and properties of the obtained composite materials were investigated.